EFFECT OF PLASTIC MULCH IN VEGETABLES PRODUCTION

Effect of plastic mulch in vegetables production. 2011

EFFECT OF PLASTIC MULCH IN VEGETABLES PRODUCTION

1. Introduction

1.1. Background Vegetables production is one of the emerging businesses in Nepal both

in on season and off season. But the yield of the vegetables is low as

compared to the other countries in Nepal. Although many efforts had

laid out for its improvement the desired level of the expectation

cannot be met till now. The total production of the vegetables in the

year 2066/67 was 275406 mt from the area 225154 ha with the

productivity of 12233 kg/ha. The contribution of the agriculture in

the total national GDP is 32.60% out of which the contribution of the

vegetables sector in national GDP is 9.7% (VDD, 2066/67). The income

is quite far better than any other crops i.e. 2-4 times more cash

than other crops. Efforts have been made to increase the

production per unit area. Vegetables have much importance as

economic, nutritional, medicinal, and industrial and also have

employment opportunities. It needs 1.5 times more labor than

other crops.

Since the beginning of civilization, the man had developed

technologies to increase the efficiency of food production. The

use of plastic mulch in commercial vegetable production is one of

these traditional techniques that have been used since 1950’s. A

favorable soil-water-plant relation is created by placing mulch

over the soil surface. The microclimate surrounding the plant and

soil is significantly affected by mulch i.e. the thermodynamic

environment, the moisture, the erosion, the physical soil

Prepared by: Amit Khanal, M.Sc. (Horticulture)Page 1


structure, the incidence of pests and diseases, crop growth and

yield. In order to maximize water use efficiency by the plant and

to improve the quality of produce, the use of mulch has become an

important cultural practice in many regions of the world for the

commercial production of vegetable crops.

Mulching is an agricultural cropping technique that involves

placing organic or synthetic materials on the soil around plants

to provide a more favorable environment for growth and

production. Organic mulches are being used traditionally by the

farmers. The most commonly used organic mulches in Nepal are:

rice straw, wheat straw, dried maize plant, sugarcane leaves,

grass clippings, etc.

The use of plastic mulch has brought a considerable change in

vegetable production in many countries. In temperate countries

the year round production of vegetables has been possible with

the use of plastic mulches. The growing period of crops with a

tropical origin have also been extended (Lamont, 1991). The

plastic mulch may be transparent, black, red, yellow or others

depending on the purpose of the mulch (Rudich, 1979).

1.2. Problem and RationaleLower productivity of vegetables in Nepal is due to excessive

rainfall, drought, weeds, pest and diseases, poor cultural

practices, leaching of the nutrients from the soil and low soil

fertility. The high night and day temperatures are the common



phenomenon in terai region that may be accounted for the reduced

flowering, fruit set and ultimately lower yield vegetables.

Mulching is one of the techniques which can help to reduce all

these problems and increase the crop yield. A favorable soil-

water-plant relation is created by placing mulch over the soil

surface. The microclimate surrounding the plant and soil is

significantly affected by mulch i.e. the thermodynamic



yield. In order to maximize water use efficiency by the plant and

to improve the quality of produce, the use of mulch has become an

important cultural practice for commercial production of

vegetable crops. This is one of the least cost methods to

increase vegetables production in Nepal which is helpful to the

small holder also.

Plant growth performance and yields of various vegetable crops

such as muskmelon (Battikhi and Ghawi, 1987; Bonanno and Lamont,

1987), water melon (Bhella, 1988a), tomato (Bhella, 1988b), red

pepper (Kwon, 1988) and eggplant (Carter and Johnson, 1988) can

be significantly improved by mulching.

Mulches reduce weed growth by making conditions unfavorable for

germination of weed seeds and by providing physical barrier for

emerging weeds. A good mulch layer can save many hours of

laborious weeding. Fumigants like methyl bromide can be used

effectively under plastic mulch to provide successful season long



control not only over weeds but also on fungal and bacterial

diseases and plant parasitic nematodes (Noling and Becker, 1994).

Mulches are very useful for maintaining uniform moisture

condition of the soil. Water loss through evaporation is

decreased, and soil erosion is decreased as the impact of heavy

rainfall is reduced by the layer of mulch. Mulch also reduces

splacing of soil onto the fruits, leaves and other parts of the

plant. This keeps the product cleaner and helps prevent the

spread of disease (Lamont, 1991).

Black plastic mulch can accelerate crop production by as much as

one to two weeks. Clear plastic mulch has shown to increase

earliness by as much as three weeks in cool climates. Weed

growth, however, can be a major problem under clear plastic

unless appropriate herbicides or fumigants are used (Lamont

1991).

Plastic mulch is nearly practically impervious to carbon dioxide,

a gas that is of prime importance in photosynthesis. Research has

shown that very high levels of CO2 may build up under the

plastic, because the film does not allow it to escape. It has to

come through the holes punched in the plastic for the plants and

a “chimney effect” is created, resulting in localized

concentrations of abundant CO2 for the actively growing leaves

(Lamont, 1991).



Mulches also help in reducing the fertilizer losses. Flood and

furrow irrigation techniques tend to leach nitrogen and other

water soluble nutrients below the root zone. Since plastic mulch

techniques generally include drip irrigation, nutrient loss is

kept to a minimum. Nutrients can be injected into the drip system

and accurately delivered to the root zone. Organic mulches add

nutrients to the soil as they decompose, improving its tilth and

moisture holding capacity (Lamont 1991).

Mulches have been found to be useful for the control of insects.

Use of reflective silver and white plastic mulches to delay onset

of aphid vectored viruses in summer squash has been well

documented in the research literature (Conway et al. 1989; Lamont et

at. 1990). As yellow color is known to attract insects, yellow

color plastic can be used to control insect with insecticide

spray over the mulch (Lamont 1991).

Mulch also helps reduce the disease incidence. Mulch application

increased microbial activity and biomass in soil (Manna et al.

2001) and reduced the severity of some above ground diseases of

plants in crops such as tomatoes (Abbasi et al. 2002).

1.3. Objectives

To identify the effect of different (organic and inorganic)

mulch in vegetables production.



2. Literature Review

2.1 Effects of mulching on soil environment

2.1.1 Effects on soil temperature

Soil temperature is modified by mulches to various degrees.

Plastic mulches warm the soil more quickly, increasing early

plant development in the cooler months. However, under high

temperature conditions during the summer, plastic may warm the

soil to temperatures that might be deleterious to plant growth.

Organic mulches act as insulation, helping keep soil cooler and,

therefore, should be applied in the hot seasons (Relf and

McDaniel, 2004).

Several reports showed that mulch application can modify the soil

temperature. Organic mulch as well as reflective plastic mulch

helps reduce the soil temperature while the clear and black

plastic mulch increases the soil temperature. Organic mulches

reduce the soil temperature by protecting the soil from direct

heat of the Sun. Dhesi et al. (1964) and Sing et al. (1966) observed

reduced soil temperature with the use of organic mulches in

potato.

Schalk and Robbins (1987) found aluminum mulches (aluminum and

aluminized plastic films) lowered soil temperatures and reduced

heat stress for young tomato Seedlings increasing their survival

in the fall season.



Tu et al. (1991) studied the effectiveness of clear plastic mulch

for the control of southern blight disease of tomato and found

that temperature under soil surface 5cm in depth could be

increased by 12°C after mulching and soil temperature could be

reached at or over 40°C after 119 hours, while the soil

temperature of control plot without mulching never reached 40°C.

The highest and the lowest temperature of soil were 51°C and 27°C

for the plot with mulching treatment, and were 39°C and 23°C for

the control plot without mulching treatment, respectively.

Teasdale and Abdul-Baki (1995) found increased soil temperature

under black polythene mulch which probably accounted for greater

early root and shoot growth and greater early yield of tomatoes

grown with black polyethylene than hairy vetch residue or bare

soil.

Hooda et al. (1999) also found that mulch with black polyethylene

recorded significantly higher soil temperature compared to other

mulch materials and the control (no mulch). Similarly the study

carried out by Diaz-Pérez and Dean Batal (2002) showed that daily

mean values of root zone temperature (RZT) under plastic mulches

were higher (1 to 5°C) than those of air temperature. The highest

RZT at mid day occurred under black mulch, and the lowest under

bare soil and white mulch. Bare soil showed the largest diurnal

RZT fluctuation.

A study was conducted by Gough (2001) to find out the effect of

color of plastic mulch on root development of pepper and found



highest mean soil surface temperature under red polyethylene

mulch and lowest on the bare soil. Temperature 5 cm beneath the

surface of all treatments was 7°C lower than at the surface, with

the greatest difference occurring beneath the red mulch and the

least beneath the silver. Red plastic mulch had the highest

subsurface soil temperature while bare soil and silver mulch had

the lowest. Averaging the surface and subsurface mean

temperatures, the red mulch provided the warmest and the silver

the coolest soil environment, bare soil and black mulch being the

intermediate.

The soil temperature under a plastic mulch depends on the thermal

properties (reflectivity, absorbitivity, or transmittancy) of a

particular material in relation to incoming solar radiation.

Black plastic mulch, the pre dominate color used in vegetable

production is an opaque blackbody absorber and radiator. Black

mulch absorbs most ultra-violet (UV), visible, and infrared

wavelengths (IR) of incoming solar radiation and re-radiates

absorbed energy in the form of thermal radiation or long-

wavelength infrared radiation. Much of the solar energy absorbed

by black plastic mulch is lost to the atmosphere through

radiation and forced convection. The efficiency with which black

mulch increases soil temperature can be improved by optimizing

conditions for transferring heat from the mulch to the soil.

Because thermal conductivity of the soil is high relative to that

of air, much of the energy absorbed by black plastic can be

transferred to the soil by conduction if contact is good between



the plastic mulch and the soil surface. Soil temperatures under

black plastic mulch during the daytime are generally 5° F higher

at a 2-inch depth and 3° F higher at a 4-inch depth compared to

those that of bare soil. Locher et al. (2005) revealed that use of

dark colored mulch is the safest solution because even in case of

high air temperature and solar radiation, the soil does not warm

to a harmful degree.

In contrast, clear plastic mulch absorbs little solar radiation

but transmits 85% to 95%, with relative transmission depending on

the thickness and degree of opacity of the polyethylene. The

under surface of clear plastic mulch usually is covered with

condensed water droplets. This water is transparent to incoming

shortwave radiation but is opaque to outgoing long wave infrared

radiation; so much of the heat lost to the atmosphere from a bare

soil by infrared radiation is retained by clear plastic mulch.

Thus, daytime soil temperatures under clear plastic mulch are

generally 8 to 14° F higher at a 2-inch depth and 6 to 9° F

higher at a 4-inch depth compared to those of bare soil. Clear

plastic mulches generally are used in the cooler regions. Using

clear plastic mulch will require the use of an herbicide, soil

fumigant, or solarization to control weeds

white-on-black or silver reflecting mulches can result in a

slight decrease in soil temperature -2° F at 1-inch depth or -

0.7° F at a 4-inch depth compared to bare soil, because they

reflect back into the plant canopy most of the incoming solar



radiation. These mulches can be used to establish a crop when

soil temperatures are high and any reduction in soil temperatures

is beneficial. Depending on the degree of opacity of the white

mulch, it may require the use of a fumigant or herbicide because

of the potential weed growth.

Clear plastic is believed to achieve higher soil temperatures

than black plastic. This happens because much of the incident

radiation is absorbed by colored films (Argall and Stewart, 1990)

and does not pass through to the soil. Results indicated that

clear plastic heated soil less than black plastic, if it was

placed tightly across the soil with good contact between the soil

surface and the mulch. They also suggested that if clear plastic

mulches placed loosely over the soil an insulating air layer

develops which results in the soil heat storage and reducing heat

loss.

2.1.2 Effects on soil moisture

Water is essential for growth and development. It is also a major

cost in agricultural systems. The success of many agricultural

forms relies on conservative and efficient use of water. Moisture

retention is undoubtedly the most common reason for which mulch

is applied to soil. Mulch is used to protect the soil from direct

exposure to the sun which would evaporate moisture from the soil

surface and cause drying of the soil profile. The protective

interface established by the mulch stops raindrop splash by

absorbing the impact energy of the rain, hence reducing soil



surface crust formation. The mulch also slows soil surface runoff

allowing a longer infiltration time. These features result in

improved water infiltration rates and higher soil moisture. An

auxiliary benefit of mulch reducing soil splash is the decreased

need for additional cleaning prior to processing of the herb

foliage (Barker, 1990). Organic and inorganic mulches have been

shown to improve the moisture retention of soil. This extended

water holding ability enables plants to survive during low

rainfall periods. The use of plastic mulch can be improved if

under-mulch irrigation is used in combination with soil moisture

monitoring. The influence of rainfall events are not as great

when plastic mulch is used, necessitating active irrigation

management. Under mulch, irrigation of vegetable crops has been

shown to improve crop yields more than overhead irrigation

systems (Clough et al., 1990). Mulch enables the soil moisture

levels to maintain for longer periods. In some cases while

providing improved moisture conditions within the soil, the mulch

changes the plants microclimate so that it uses more water (Clark

and Moore, 1991 and Zajicek and Heilman, 1991), thus negating the

initial benefit. Plastic mulch conserved 47.08% of water and

increased yield by 47.67% in tomato when compared to un-mulched

control (Friake et al., 1990). Palada et al. (2003) concluded that

plastic mulching resulted in 33 to 52% more efficient use of

irrigation water in bell pepper compared to bare soil.

Soil moisture levels are usually higher under mulched than

unmulched soil because the mulch acts as a vapor barrier which



reduces evaporation. The effectiveness of polyethylene coated

paper mulches in altering soil environment was investigated by

Liptay and Tiessen (1970). They found that polyethylene coated

paper mulches were as effective in reducing soil moisture

evaporation as the polyethylene mulches. But non- coated paper

mulches were not as effective as the coated mulches. Evaporation

from the bare soil was greater than from all the mulched plots;

however, irrigated, bare soils reach 100% of available water much

sooner than mulched soils.

Shrivastava et al. (1984) found that the organic mulches

effectively conserve the soil moisture in summer tomato

cultivation. They found the frequency of irrigation was reduced

by 55.5% by the mulch application without any adverse effect on

yield.

2.1.3 Effects on soil structure

Soil compactness is generally less under mulch than in bare soil.

Water from rain or irrigation falling directly on the soil tends

to compact the surface of the soil thus reducing soil aeration.

Specific mulches spread the impact of the water droplets over a

large surface area and reduce soil compaction (Liptay and

Tiessen, 1970). McIntyre et al. (2000) found lower soil bulk

density in the mulched treatments than in bare soil treatments in

0 to 0.5 meter depth. However below 0.5 meter depth there were no

significant differences between the mulched and bare soil

treatments. But Famoso and Bautista (1983) reported increased



bulk density of the soil with the use of sugarcane bagasse as

mulch in tomato. As reported by Tindall et al. (1991), straw mulch

resulted significantly greater infiltration rate, and lower pH,

bulk density, surface evaporation, cone index, soil temperature

and matrix potential than the plastic mulch.

2.2 Effects on nutrient level

Mulches also help in reducing the fertilizer losses. Flood and

furrow irrigation techniques tend to leach nitrogen and other

water soluble nutrients below the root zone. Since plastic mulch

techniques generally include drip irrigation, nutrient loss is

kept to a minimum. Nutrients can be injected into the drip system

and accurately delivered to the root zone (Lamont, 1991).

Liptay and Tiessen (1970) found that nitrate-N level of the soils

under mulches were higher than in the bare soils. But no

significant difference was observed between different mulch

treatments.

Famoso and Bautista (1983) found that mulching tomato with

sugarcane bagasse left to decompose for 8 months after milling

increased phosphorous and potash as well as organic matter

content of the soil.

Chilli plants grown on plastic mulch had significantly higher N

and K contents in leaf tissues at early fruiting stage when

compared with bare soil (Hassan et al., 1995).



A 3-year experiment was conducted to determine the optimum

fertilizer N requirements of fresh-market tomato grown on a hairy

vetch (Vicia villosa Roth.) or black polyethylene mulch. Tomatoes

grown under black polyethylene mulch required N at the rate of

130 to 144 kg/ha to achieve yields equivalent to those grown

following unfertilized hairy vetch (Abdul-Baki et al. 1997).

McIntyre et al. (2000) conducted a study to determine the effect of

mulching on above-and below ground biomass, soil and foliar

nutrient level and soil water uptake in banana. They found soil

organic C, P, and exchangeable K and Mg were significantly higher

in the mulched treatments than in bare soil.

2.3 Effects of mulching on weed growth

Weed control in crops is a difficult, time consuming and

expensive task. Plastic mulches have the potential to alter soil

temperature, crop water use, improve crop quality and in some

cases reduce weed competition, thereby improving crop development

and increasing yields (Lamont, 2005 and Ngouaajio and Ernest,

2005). Black plastic mulch is both effective at warming the soil

and reducing weed competition. Clear plastic mulch provides

greater soil warming, but it does not reduce the weed competition

(Lamont, 2005). Dark colored mulches lie across the soil and

around the crop reduce the amount of light reaching the soil and

thus inhibit weed germination and smother emerging weeds.

Mulching for weed control can take a number of forms: inorganic

or organic mulches can be applied and left in situ to control the



weeds; living mulches can be grown to choke out weeds before

planting the mulches are either killed with chemicals or complete

their life cycle before the growing season of the herb.

Solarisation uses an inorganic mulch and solar energy to

disinfect the soil, the mulch being removed prior to planting.

Similarly 100% weed control was observed in cassava peel with

black plastic mulch as compared to bare soil (Aniekwe et al.,

2004).

Weeds in tomato pose a serious problem and effect the crop

resulting about 57.6 percent reduction in yield (Singh and Singh,

1992). The demand for integrated weed management approaches has

resulted from increasing energy, labor and material costs

associated with weed control practices in conventional cropping

systems. Degraded herbicide compounds have also been detected in

surface and ground waters (Kolpin et al. 1997), generating an

interest in alternative strategies.

Economically and environmentally sustainable weed control

alternatives, such as non-synthetic or natural mulches can

provide many benefits, including weed suppression and delayed

weed emergence (Teasdale and Mohler, 1993). Increasing interest

in more biologically based cropping alternatives and pressure to

reduce the use of herbicides has led researchers to test organic

mulches for their ability to reduce weeds (Creamer et al. 1996;

Teasdale and Abdul-Baki, 1998). Among the organic mulches, winter

annual legume hairy vetch (Vicia villosa R.) not only increased tomato



yield relative to plastic mulch but also reduces weed emergence

and water loss (AbdulBaki, and Teasdale, 1993).

Shrivastava et al. (1994) have recommended use of drip irrigation

along with plastic mulch in the areas of high weed intensity.

This treatment resulted in 95% reduction in weed infestation,

53% higher yield and 44% saving in irrigation water when compared

with the surface flood without mulch treatment.

Sudha et al. (1998) conducted field studies on soil solarization

for weed control in tomatoes and tobacco nursery beds and found

the lowest weed count and weed dry matter in soil solarization

with transparent polyethylene followed by soil solarization with

black polyethylene.

Some species of Brassica family when used as mulch caused temporary

weed suppression which is probably due to secondary plant

metabolites (Al-Khatib et a!.. 1997). Brassica spp. contain high

amount of glucosinolates. These secondary plant metabolites play

a key role for weed suppression as they can be converted to the

corresponding isothiocyanates by the plant enzyme myrosinase and

these isothiocyanates are phytotoxic (Fenwick et al., 1983). Living

plants do not actively release high amounts but during

decomposition of dead plant material or by incorporating green

plant material into the soil, larger amounts of isothiocyanates

can be released (Petersen et al., 2001). If Brassica spp. plant

tissues are incorporated into the soil, it is possible to control

weeds in the following crop by isothiocyanates released from the



mulch (AI-Khatib et al., 1997). This might be a chance to reduce

the use of herbicides and could be an additional tool to control

herbicide-resistant weeds.

The phytotoxic properties of some other plants as cover crop and

mulch were also studied by others. And in some cases this

property makes a disadvantage to the tomato crop. A 5-yrs field

experiment conducted by Caamal-Maldonado et al. (2001) evaluated

the effect of four legumes, velvet bean (Mucuna deeringiana Merr.)

and jackbean (Canavalia ens forinis L.) used as living cover crops, and

jumbiebean (Leucaefla leucocephala L.) and wild tamarind (Lysiloma

tatisiliquum L.) used as dead mulches incorporated on soil surface,

on weed growth and corn yield. The number, biomass, diversity,

and relative importance of weeds, as well as corn yield were

evaluated. All legumes reduced weed growth with velvet bean (as

living cover crop) producing the largest weed biomass reduction

(68%). They also conducted in-vitro bioassay and greenhouse

experiment to evaluate the toxic effect of above four legumes.

The aqueous leachates of all four legumes exhibited strong

photoxic effect the radicle growth of the all three test plants

viz, barnyard grass (Echinochloa crusgalli L.), amaranth (Amaranthus

hypochondiacus L.) and tomato. Velvetbean and jackbean caused the

highest inhibition on amaranth radicle growth. Tomato was

strongly inhibited by jackbean and by other treatments an

indication that the use of these legumes as mulches in tomato

crop should be avoided (Caamal-maldonado et al., 2001).



Masiunas et al (2003) conducted a study to determine the effect of

foam mulch and its color on weed control and on yields of basil

and tomatoes. The foam mulch controlled weeds comparable to black

plastic mulch. However the color of foam mulch did not affect

weed control because it did not allow light penetration and

served as a physical barrier impeding weed emergence.

2.4 Effects of mulching on vegetative characters

2.4.1 Effects on seedling and plant growth

Organic or inorganic soil mulches influence the crop in a number

of ways. Plastic mulches can offer a barrier against weeds,

moisture loss, nutrient loss, erosion, insect and disease injury

while encouraging plant establishment and an earlier crop of

potentially higher quality (Mugalla et al., 1996). The combined

effects of soil temperature, soil moisture and weed suppression

not only work to improve crop growth but they also facilitate

hand picking and lead to higher yield and increased fruit size

(Scheerens and Brenneman, 1994).

Mulching with black or clear plastic increased total plant growth

and led to an increased rate of branching and early flowering in

tomato (Wein and Minotti, 1988). Hassan et al. (1995) reported that

mulching is practically beneficial in chilli production. They

concluded that increased plant growth for mulched plants may be

related to soil moisture content because plant dry weight was

positively correlated with soil temperature and moisture content.

Hallidri (2001) stated that plant height and number of leaves



were higher in black and transparent polythene mulch than control

(bare soil) while no significant difference was observed in case

of stem diameter in cucumber.

Karp et al. (2006) reported that mulching treatment significantly

influenced nutrient content of leaves and chlorophyll contents

(381 SPAD units) were significantly lower in control plants

compared with plants grown on different mulches (498 and 542 SPAD

units). Plastic mulches increased crop growth (3.2–4.0 cm), dry

root mass (12.2–50.1%), nitrogen fixing activity (3.3–12.8%),

leaf chlorophyll content (41–78%) more reproductive buds (63.3–

94.1%) and starts flowering 9 days earlier in groundnut than un-

mulched control (Hu et al., 1995).

Vandenberg and Tiessen (1972) found growth of direct seeded

tomato plant was accelerated by both wax and polyethylene coating

on paper mulches. Albregts and Howard (1973) also found

germination of okra and early growth of okra and pepper were

greatest in the full mulch beds. Strip mulching increased the

early plant growth of pepper, but by midseason the advantage over

the unmulched treatment was no longer significant.

Mulching significantly increased vegetative growth, yield and

yield components of the tomato plants (Olasantan, 1985). Mulched

plants grew taller and had more branches than unmulched controls.

Schalk and Robbins (1987) observed increased plant height in

tomatoes with the application of aluminum mulches (aluminum and

aluminized plastic films).



Wien and Minotti (1987) observed that total plant growth, as

measured by vine weights at final harvest, was increased by

plastic mulching. But in an experiment conducted by Gunadi and

Suwandi (1987), mulching did not significantly affect the growth

components. However, there was a tendency for the yield

components to increase by the application of straw mulch.

Ann and Ankara (2001) found that mulch application significantly

influenced plant height in tomato. They observed highest plant

height in tomato with straw mulch. Straw and transparent

polyethylene mulches recorded higher stem diameter than other

treatments.

Plastic mulches increased crop growth (3.2–4.0 cm), dry root mass

(12.2–50.1%), nitrogen fixing activity (3.3–12.8%), leaf

chlorophyll content (41–78%) more reproductive buds (63.3–94.1%)

and starts flowering 9 days earlier in groundnut than un-mulched

control (Hu et al., 1995).

The effect of plastic mulch and its color improve soil structure,

crop growth and its development. Growth, yield and nutrient

uptake are affected by plastic mulch and initial nitrogen levels

in the soil (Wein and Minotti, 1988).

The number of leaves per plant or dry weight per plant better

explains the changes in watermelon yield than net photosynthesis

rate (Ibarra-Jimenez et al., 2005). Similarly plant height, number

and length of main roots, fresh and dry weights of roots as well



as number of flower were significantly higher in plants grown on

mulch as compared to bare soil (Hasan et al., 2005). Leaf area

ratio and leaf weight ratio were not significantly different in

melon grown under plastic mulch but 10-20% higher than those on

the bare soil (control) (Lopez et al., 2000).

2.4.2 Effects on root growth and distribution

Little work has been done to describe the influence of mulch on

the root growth and distribution of vegetable crops. Wein (1997)

speculated that root growth and distribution was significantly

influenced by soil structure and management, including

cultivation, irrigation and the use of polyethylene mulch in

pepper. Gough (2001) reported that pepper plants grown under

silver mulch produced greatest number of lateral roots followed

by bare soil and black mulch, and the fewest roots under red

mulch. Color mulches influenced the total number of adventitious

and lateral roots but not the root system architecture of pepper

plant. Plants grown under mulch had fewer but thicker

adventitious roots. Wein et al. (1993) reported that tomato roots

were significantly longer 1 week after transplanting on plants

grown under clear polyethylene than on these grown without mulch.

Gupta and Acharya (1993) observed increased root mass under black

polyethylene mulch was attributed to the resultant increase in

soil temperature and nutrient uptake.

Kirnak and Demirtas (2006) both root and shoot dry weights of

cucumber plants were significantly improved by plastic mulch.



Similarly plant height, number and length of main roots, fresh

and dry weights of roots as well as number of flower were

significantly higher in plants grown on mulch as compared to bare

soil (Hasan et al., 2005).

2.5 Effects of mulching on flowering and fruit setting

The effects of mulching on flowering and fruit setting were

studied by Vandenberg and Tissen (1972). The wax and polyethylene

coated paper mulch increased number of flower clusters, flowers

and fruit per plant. However, the response was higher in

polyethylene coated paper than in wax coated paper. Earlier

flowering was also observed in mulched plots relative to bare

plots. Famoso and Bautista (1983) observed increase in total

number of flower per plant when tomato was mulched with

sugarcafle bagasse.

Mulches ameliorated soil hydrothermal regime, improved vegetative

growth, advanced flowering and fruit yield of tomato plants when

compared with bare soil (Agele et al., 2000).

2.6 Effects of mulching on earliness

Wien and Minotti (1987) found plastic mulching led to early

flowering in tomato. West and Peirce (1988) observed black

polyethylene mulch and polyester row cover causes earliness

contributing to an increment in early eld. Wien and Minotti

(l988a) reported plastic mulch increased early flower number,

hastened flower production, and increased early yield in tomato.



Hastening of maturity of plants on mulch resulted in a 22%

increase in ripe fruit and a decrease in percent green fruit at

final harvest. Peirce and (1989) also reported earliness in

flowering and ripening in tomato with black polyethylene mulch.

Though plastic mulch can help earliness organic mulch tends to

delay maturity. Rarnalan and Nwokeocha (2000) found rice straw

mulch significantly delayed the attainment of 50% fruiting by 6

days compared to the un-mulched plots. Similarly Ann and Ankara

(2001) also recorded shortest time for harvest in transparent and

black polythene mulch though the total yield was highest in wheat

straw mulched plots.

Vegetable crops grown under plastic mulches have shown earlier 7

to14 days and increased yields 2 to 3 times over vegetable crops

grown on bare soil (Lamont, 1993). Black plastic mulch doubled

the yield of tomatoes as well as increasing the amount of early

production for some cultivars when compared with un-mulched

control (Abdul- Baki et al., 1992).

2.7 Effects on total yield

Shrivastava et al. (1984) reported that the use of organic mulch in

tomato increased the yield and Kans grass (Saccarum spontaneum) as

mulch was found most effective giving 40 percent higher yield

than soil cultivation. Patil et al. (1973) and Sukia and Prabhakar

(1988) also obtained increased yield of tomato with polythene

mulching. Gunadi and Suwandi (1987) observed that the application

of straw mulch increased 15% of total yield and 16.3% of



marketable yield compared to no mulching. Similar observations

were made by Gupta and Gupta (1987) where straw mulching (6 T/ha)

together with light and frequent irrigation (30 mm water at E0=30

mm) to a sandy loam soil increased tomato yield up to 100%. Mulch

treatments improved the yields of tomato and the greatest yield

of large and extra-large fruits were obtained from plants grown

with aluminum alone, with aluminum laid over black plastic and

with black plastic alone (Schalk and Robbins, 1987). Ariyarathne

(1989) also reported mulching in tomato increased the marketable

and the total fruit yields as well as the number of marketable

fruit significantly.

Shrivastava et al., (1994) Conducted experiments from 1989 to 1991

to study the effect of drip, mulches (black plastic and Sugarcane

trash) and irrigation levels on tomato yield. This study revealed

that drip plus sugarcane trash mulch was the best combination,

which gave the highest fruit yield of about 51 metric Tons/ha

with 44% water saving.

A field trial conducted at AVRDC during the autumn season

revealed that yield of non-staked tomato was increased by 67.5%

when the crop was mulched with black plastic and by 15% when it

was mulched with rice straw. The high yield of plastic mulch

treatment was in terms of a high number of fruits per plant

(Sajjapongse et al., 1989). Hooda et al. (1999) also found highest

yield attributes in the black polyethylene mulch.



Field experiments were conducted in Assam, India to evaluate the

effectiveness of different organic mulches including black

polyethylene sheet on tomato and okra by Sannigrahi and Borah

(2002). The mulch treatments were black polyethylene sheet, rice

straw, spent straw, water hyacinth (Eichhomia crassipes), thatch

grass (Imperata cylindrica), and no mulch (control). Mulching

increased the number of tomato fruits per plant and had higher

crop yield than the control. Water hyacinth mulch gave the

highest increase in tomato yield (by 91%).

Wien and Minotti (1987) conducted two field experiments with and

without plastic mulch in 1982 and 1983. Effects of the plastic

mulch dominated both experiments. Mulching increased early yield

only in 1983, but increased total yields by 13% and 79% in 1982

and 1983, respectively. Similarly in another experiment Wien and

Minotti (1988b) recorded 25% increase in yields of the first four

harvests in tomatoes with clear plastic mulch.

Bogle et al. (1989) compared performance of different plastic

mulches for three consecutive growing seasons. Use of black

plastic mulch resulted in 31% and 16% greater marketable tomato

yield in spring 1983 and 1984, than similar bare-soil (unmulched)

treatments, respectively. In fall 1983, use of white/black

(top/bottom) laminated plastic mulch reduced yields by 12%

compared to similar unmulched treatments.

Csizinszky et al. (1995) conducted a field research in three

seasons to find out the effect of plastic mulch having six colors



on yield and insect pest incidence in tomatoes. It was found that

extra-large and marketable fruit yields were higher at blue

mulch, whereas early marketable yields were higher at red mulch.

Asiegbu (1991) compared performance of four mulching materials

(viz. Black p1astic, cassava peel, giant star grass and guinea

grass straw) and found that black plastic mulch was most

effective in weed control and resulted in more crop growth and

higher fruit yield of tomato and eggplant.

Vegetative cover crops, particularly hairy vetch, have been shown

to be a profitable management practice for fresh-market tomato

production resulting in higher tomato yields and lower production

costs than polyethylene mulch or bare soil (Kelly et al. 1995).

Gross returns from tomatoes grown in hairy vetch residues were

also higher than from the polyethylene mulch. The combination of

environmental benefits and the economic benefits to the grower

make the hairy vetch mulch system an attractive alternative for

producing fresh-market tomatoes in the Mid-Atlantic and parts of

northeastern United States (Kelly et al. 1995). Abdul-Baki et al.

(1996b) found higher yields and heavier fruit in hairy vetch than

in bare soil or black polyethylene mulch. Abdul-Baki et al. (1997)

also found that tomato yields were higher for the hairy vetch

than for the black polyethylene mulch.

Abdul-Baki et al. (2002) conducted a field research in 1996 and

1997 to compare the marketable yield of 12 fresh-market tomato

genotypes when grown under plastic and hairy vetch mulches.



Tomatoes were grown in conventional tillage plastic mulch and no-

till hairy vetch mulch. The yield of’ eight of the genotypes was

significantly higher in the hairy vetch mulch than in the plastic

mulch system in both the years, ranging from 12% to 57% higher in

1996 and 10% to 48% higher in 1997.

But in a similar study, Creamer et al. (19%) found that tomato

yield was lower with a cover crop mixture containing hairy vetch

as the dominant component than without a cover crop. Similarly,

Yaffa et al. (2000) also found that hairy vetch as a cover crop

increased soil inorganic nitrogen, but it did not increased

tomato yield. Further studies are needed to evaluate the effects

of a hairy vetch cover crop on fresh market tomato, because hairy

vetch has been known to substantially increase tomato yield

(Abdul-Baki and Teasdale, 1993; Kelly et al., 1995; Abdul-Baki et al.,

1996a).

An experiment was carried out by Ann and Ankara (2001) to

determine the effect of low-tunnel, mulch and pruning treatments

on yield and earliness of tomato in unheated glasshouse. Among

the mulch applications, the wheat straw gave the highest yield

while the control gave the lowest. The average fruit weight was

also significantly higher in the crops grown under straw mulch.

A general increase in plant growth and fruit size in hot peppers

was observed by the use of plastic mulch while clear plastic

mulch increased the early and total yield by 39% and 19%

respectively (Pakyurel et al., 1993).



Brown et al. (2001) reported that bell peppers grown on black

plastic mulch alone or in combination with drip irrigation

increased pepper yields by 18 and 16 metric tons ha-1

respectively when compared with bare soil.

2.8 Effects of mulch colors on plant growth and development

The change in vegetable crop yield in response to the different

mulch colors is due in part to an increase in soil temperature

and the range of reflected wavelengths produced by individual

mulch colors (Orzolek and Otjen, 2003). Natural soils and plant

residues (including mulches) are of many colors, and they can

reflect a wide range of photosynthetic and morphogenic light to

influence yield and quality of growing plants. Photosynthetically

active light is a well-known component of the growth environment,

contributing to more than 90% of the dry matter through

photosynthetic process (Kasperbauer, 1992). The most influential

colors of morphogenic light appear to be far- red (FR), red (R),

and blue (BL) (Antonious and Kasperbauer, 2002).

The ratio of far-red to red light is important in phytochrorne

regulation of plant physiological process (Borthwick, 1972) and

is a dominant factor in distribution and use (partitioning) of

photosynthate within developing plants (Kasperbauer and Hunt,

1992).

On the basis of earlier controlled environment experiments

(Kasperbauer, 1971), it was predicted that a FR/R photon ratio

higher than the ratio in incoming sunlight (at the same time and



place) would favor shoot crops, and a FR/R ratio lower than the

ratio in incoming light would favor below ground crops.

Kasperbauer (1992) also concluded that the mulch surface colors

that reflected FR/R ratio higher than the ratio in incoming

sunlight resulted in plants that allocated more photo assimilate

to shoots, including fruit.

Different mulch colors reflect different wavelengths and thus

different FR/R ratios (Orzolek and Otjen, 2003). Red plastic

mulch reflected a FR/R photon ratio that was higher than the

ratio in incoming sunlight at the same time and place

(Kasperbauer, 1999). It favored above-ground growth, including

fruit yield of high value crops such as tomato (Kasperbauer and

Hunt, 1998) and strawberry (Kasperbauer, 2000). In addition to

the higher yield of these two crops, the color of light reflected

to the fruit during its development also influenced concentration

of some flavor and nutrient components in the ripe fruit

(Kasperbauer et al. 2001). Light reflected from red mulch had a

higher FR/R ratio than normal sunlight (Matheny et al. 1992) and

the higher FR/R ratio helped enhance the carbohydrate movement

into the developing tomato fruit resulting in increased early

production (Kasperbauer and Hunt, 1998). Similarly, soybean

seedlings developed longer stems over green and red mulches which

reflected higher FR/R ratio than were present in incoming

sunlight whereas the largest roots and lowest shoot/root biomass

ratio for root crop (radish) developed over orange mulch, which



reflected a FR/R ratio lower than the ratio in incoming sunlight

(Kasperbauer, 1992).

The influence of color of Polyethylene mulch on tomato production

was investigated by Decoteau et al. (1989). Tomato plants grown

with red mulch generally had the greatest early marketable yields

and produce the least amount of foliage. Plants grown with a

white or sliver colored mulch had lower early marketable yields

but produce more foliage. These results suggest that mulch

surface color can induce changes in the plant microclimate (e.g.

spectral balance and quantity of light, root zone temperatures)

that can act through natural regulatory system within the growing

plant and affect through natural regulatory system within the

growing plant and affect tomato plant and fruit production.

Chaudhary et al. (2002) conducted an experiment at National

Agriculture Research Centre, Islamabad, Pakistan to investigate

the effect of different colored (black, red and green) plastic

mulches on nutrient contents, growth and yield of tomato. They

found the effect of different colored plastic mulch on the tomato

yield was significant. The highest value was recorded with green

plastic mulch, followed by red and black plastic mulch. The

lowest value was recorded in the control. The green plastic

mulch, red plastic mulch and black plastic mulches produced 154,

101 and 40% yield increase over control.



Masiunas et al. (2003) also found the effect of mulch color on

total yield of tomato. They obtained highest tomato yield in the

blue color foam mulch.

2.9 Effects on fruit quality

In addition to the higher yield of the crop, the color of the

mulch also influences the chemical composition of plant products.

Bin-Abdullah (1990) found quality of marketable tomato was better

under polyethylene mulch compared with unmulched Control.

Antonious and Kasperbauer (2002) found that carrot roots from

yellow and white plastic covered plots had higher concentration

of fl-carotene and ascorbic acid and yellow and black covered

plots had higher concentration of pheriolics. Abdul-Baki et al.

(1996b) found highest soluble solid in tomatoes with black

polyethylene and lowest was had the greatest early marketable

yields and produced the least amount of foliage. Plants grown

with white or silver-colored mulch had lower early marketable

yields but produced more foliage. These results suggest that

mulch surface color can induce changes in the plant microclimate

(e.g., spectral balance and quantity of light, root zone

temperatures) that can act through natural regulatory systems

within the growing plant and affect tomato plant growth and fruit

production.

Kasperbauer and Hunt (1998) concluded that increased tomato yield

over the red plastic mulch was caused by reflection of FR to the

growing plants and its subsequent phytochrome-mediated regulation



of photosynthate allocation to developing fruit. Number, size,

and total fruit produced over the red plastic mulches were

compared with those over standard black plastic. Because soil

temperature affects production of horticultural crops (Bhella,

1988b), that component was minimized in a tomato productivity

study done by Kasperbauer and Hunt (1998). They used a layer of

red plastic over the standard black plastic which resulted in a

very similar soil temperature but quite different reflection

spectra in both the treatments (black plastic and red over the

black). This experimental system allowed evaluation of yield

response to reflected spectrum while minimizing soil temperature

effects.

Photodegradable red mulch (placed over a layer of black plastic)

increased fruit yield while it was intact, but yield dropped to

that of the black control after the red plastic degraded. Non-

degradable red plastic resulted in greater yield. Early crop

yield advantage of red mulch was evident whether it was placed

directly over soil or over a layer of black plastic (Kasperbauer

and Hunt, 1998). Similarly Kaul and Kasperbauer (1992)

investigated the effect of various plastic mulch colors (viz.

white, blue red and black) on fruit yield of peppers (Capsicum

annum L.). Data were collected on rhizosphere (soil) temperature,

spectral balance of reflected light, and fruit yield. Fruit

yields were highest over red mulch even though soil temperature

did not differ under red, black and blue mulches. However, plants

grown over red mulch received more reflected far-red light and



higher FR/R light ratio. These findings clearly showed that yield

response of tomato as well as pepper over the red mulch was also

due to the reflection not only due to the increase in soil

temperature.

2.10 Effects on insect pest population

Mulches have been found to be useful for the control of insects.

Use of reflective silver and white plastic mulches to delay onset

of aphid vectored viruses in summer squash has been well

documented in the research literature (Conway et al. 1989; Lamont

et al. 1990). As yellow color is known to attract insects, yellow

color plastic can be used to control insect with insecticide

spray over the mulch (Lamont, 1991).

Scott et al. (1989) investigated the effect of the type of mulch

used (black plastic, aluminum-painted plastic or no mulch) on

aerial thrips population in staked tomato and found that

aluminum-painted mulch was most effective in reducing the numbers

of thrips while black plastic was more effective than no mulch.

Schalk and Robbins (1987) found that aphids (Nezara viridula) were

repelled by the aluminum mulches, while fruit injury was found to

have increased due to attack by tomato pinworm (Kesferia lycopersicella)

and tomato fruit worm (Heliothis zea) which appeared to have been

attracted to the reflective surfaces.

Highly reflective mulches drive insects away, though the

mechanism isn’t fully understood. It’s believed that reflecting

UV wavelengths makes plants invisible to pests like thrips,



aphids, or white fly, so they don’t land on the plants and spread

mosaic virus (Schut, 2001).

Field studies were conducted by Csizinszky et al. (1995) for three

seasons on the effect of six mulch colors: blue, orange, red,

aluminum, yellow, and white (fall) or black (spring), on fruit

yields and on insect vectors of Sunny tomato. Aphids, thrips and

whiteflies were counted monthly in traps placed on the mulched

beds. Aphids were least numerous on the aluminum and yellow mulch

and most numerous on the blue mulch. The fewest thrips were

captured on aluminum and the fewest whiteflies were captured on

the yellows aluminum and orange mulches. Low numbers of

whiteflies on the orange and aluminum mulches delayed virus

symptom development and increased yields.

Csizinszky et al. (1999) again conducted field studies for three

seasons on the effect of ultraviolet (UV)-reflective films

(mulches) on the silver leaf whitefly and on the yield of staked,

fresh-market tomatoes. Whitefly populations in the fall season

were lower on the aluminum than on the silver mulches. In the

spring whiteflies were more numerous on the black control and

silver on white, than on aluminum mulches.

Farias-Larios and Orzoc-Santos (1997) concluded that clear

plastic mulch could be a practical management tool for reducing

insect populations, virus incidence and increasing soil

temperature, watermelon production and enhancement of fruit

quality. Aphids were less severe on clear plastic mulch than on



bare soil and black plastic mulch. Low numbers of whiteflies on

the white and clear plastic mulches during early cycle of culture

delayed virus symptom development.

2.11 Effects on disease incidence and spread

Increase in soil temperature by application of plastic mulch

caused a significant reduction in pathogen levels, at lower cost

than un-mulched, fumigated soi1 fields and at lower phytotoxicity

levels (Abdul-Baki et al., 1996). Clear plastic mulch has repellent

effect on vector; aphids, in Lupinus angustifolius (Jones, 1991),

which has reflective effect and help in reducing the appearance

of viral disease confusing aphids in cantaloupe (Orozco-Santos et

al., 1995).

Mulch also helps reduce the disease incidence. Mulch application

increased microbial activity and biomass in soil (Manna et al.

2001) and reduced the severity of some above ground diseases of

plants in crops such as tomatoes (Abbasi et al. 2002).

Hung and Chen (1985) found that the mulched plants of tomato

showed better results on disease and weed control than the un-

mulched plants. Mulching materials help reduce anthracnose, stem

rot, and virus infection. Effect of black plastic mulch on the

incidence of southern blight disease in bell pepper was

investigated by Brown et al. (1989). They found that disease

incidence and severity were lower and yields were higher in plots

with black polythene mulch than in plots with bare soil.



Tomato yellow leaf curl virus (TYLCV) is the most serious disease

of tomatoes throughout the Mediterranean region, the Middle East

and the tropical regions of the world (Makkouk and Laterrot,

1983). It is very destructive disease transmitted by whitefly,

Bemisia tabaci. TYLCV disease has become a major factor limiting

tomato production and losses range from 28 to 92% (AlMusa, 1982).

Some reports are available regarding effects of mulching on TYLCV

incidence. Mulch type and color influence growth, yield and

whitefly population in tomato (Csizinszky et al. 1995). Cohen and

Melarned-Macljar (1978) also found that soil covered by colored

plastics reduces the incidence of TYLCV in fresh market tomatoes.

Suwwan et al. (1989) studied the effect of different kinds of mulch

on the incidence of tomato yellow leaf curl (TYLC) virus. Five

different types of mulch viz, silver (aluminum treated

reflective) plastic, black plastic, paper, white/black plastic

and black/White plastic were evaluated. The incidence of TYLC

virus was reduced by silver plastic mulch. While incidence of

sunscald increased significantly in silver and white/black

plastic mulches.

Similarly tomato spotted wilt virus (TSWV) is another serious

viral disease which is spread by 2 thrips genera, Franklinielia and

Thrips. This disease has threatened almost all the tomato growers

of southern US. Farmers of the southern US are applying costly

and highly toxic broad-spectrum insecticides on a calendar basis

to control the insect vector but the researches have shown that



losses to solanaceous crops in the southern US from TSWV

typically is the result of primary infection which cannot be

prevented by insecticide use (Bauske et al. 1998). Momol et al. (2002)

conducted a five years (1996- 2000) research to study combined

effect of a insecticide (spinosad), a systemic acquired

resistance inducer (Actigard) and UV-reflective metalized mulch

on management of tomato spotted wilt virus. The overall incidence

of TSWV was significantly lower in metalized mulch plots than the

black mulch plots. Application of Actigard was effective in

reducing disease incidence on black mulch but not on metalized

mulch. The regiment of metalized mulch, Actigard and insecticides

reduced tomato spotted wilt virus by as much as 76%.

The effect of plastic film mulches on thrips immigration and

tomato spotted wilt virus (TSWV) incidence in tomato, pepper, and

tobacco fields was studied by Greenough et al. (1990). Three

treatments (aluminum surfaced plastic mulch, black plastic mulch,

arid a non mulched control) were compared. Thrips immigration

into treatments plots was estimated with the use of yellow sticky

board traps. Compared with the non mulched treatment, aluminum-

surfaced mulch reduced the numbers of trapped thrips by 68% and

the incidence of TSWV by 64% in tomato (Greenough et al., 1990).

Southern blight, caused by soil borne fungus Sclerotium rolfsii,

affects more than 500 plant species in over 100 plant families,

which is a severe problem in many parts of the world and

particularly deleterious to processing tomato (Bulluck and



Ristaino, 2002). Control of southern blight has been achieved

primarily through soil fumigation and fungicide use (Munnecke et

al. 1982.; Punja et al. 1986); however, chemical control can be

expensive and is not completely effective because of the clumped

distribution of inoculum and resilient nature of sclerotia

(Bulluck and Ristaino, 2002). Cultural control methods have been

used to manage southern blight, including application of mulches

and soil solarization (Brown et al., 1989; Ristaino et al., 1991).

Mulches (clear or colored plastic, straw, or nylon) limit disease

incidence by creating a physical barrier that prevents inoculum

contact with the above ground portion of the plant (Brown et al.,

1989). Solarization with clear plastic mulch has also been used

to reduce sclerotia survival at shallow soil depths (Ristaino et

al., 1 991). Tu et al. (1991) studied the effectiveness of clear

plastic mulch for the control of southern blight disease of

tomato and found that the mulching treatment was effective in

controlling the disease. The sclerotia of S. rolfsii could not

survive in the soil surface and under soil surface 5 cm in depth.

However, the Planting row amended with green manure and mulched

with plastic sheet was better for the disease control than the

mulching treatment alone. Similarly Brown et al. (1989) found black

polyethylene mulch effectively suppress the incidence of southern

blight in pepper.

Elmer and Ferrandino (1991) compared paper mulch and black

plastic mulch with no mulch on tomatoes for incidence of blossom

end rot. Black plastic mulch significantly increased early season



blossom end rot relative to paper or no mulch. While late season

blossom end rot was decreased with paper or black plastic mulch

relative to no mulch. However Suwwan et al. (1989) found blossom

end rot incidence was not affected by mulch treatments.

2.12 Effects on nematode infestation

Root-knot nematodes are common root parasites associated with

vegetable and field crops in temperate and tropical regions of

the world (Sasser and Carter, 1982). Root-knot nematodes

(Meloidogyne spp.) are one of the variety of root-parasitic

nematodes that establish specialized feeding cells in roots,

redirecting photosynthate produced in the leaves to supply the

energy demands of the nematode in the roots (Dufour et al., 2003)

as a result of which root biomass increases (Fortnum et al., 1991).

Colored mulches, which vary in quantity and spectral balance of

reflected light, have been shown to alter root-knot nematode

development in tomato. Plants grown over white mulch had greater

numbers of M. incognita eggs per gram dry root weight than similar

plant grown over red or black mulch. Mulch color did not alter

root mass in uninoculated plants. However, root mass in plant

grown over white mulch and inoculated with M. incognita increased

with increasing nematode population, whereas root mass of plants

grown over black or red mulch plateaued at higher nematode

populations (Fortnum et al., 1995).

The effects of different-colored polyethylene mulches on the

quantity and spectra of reflected light, earliness of fruit set,



fruit yield and quality and root-knot disease were studied in

field-grown, staked tomato by Fortnum el al. (1997). Fruit yields

were recorded for tomato plants inoculated with Meloidogyne incognita

at initial populations of 0, 1,000, 10,000, 50,000, or 100,000

eggs/plant and grown over black, white, or red plastic mulch.

Plants grown over red mulch in the spring and inoculated with

50,000 eggs of M. incognita had greater early marketable yields

than similarly inoculated plants grown over black or white mulch.

Investigations at the Agricultural Research Service in Florence,

South Carolina indicated that red plastic mulch suppresses root-

knot nematode damage in tomatoes. The red mulch reflects

wavelengths of light that cause the plant to keep more growth

above ground, which results in greater yield. Meanwhile, the

plant is putting less energy into its root system, the very food,

the nematodes feed on. So reflection from the red mulch, in

effect, tugs food away from the nematodes that are trying to draw

nutrients from the roots. The research team planted tomatoes in

sterilized soil, mulched them with red or black plastic, and

inoculated the roots with nematodes. Plants that were inoculated

with 200,000 nematode eggs and mulched with black plastic

produced 8 pounds of tomatoes, while those mulched with red

plastic produced 17 pounds (Dufour et al., 2003).

3. Conclusion



A favorable soil-water-plant relation is created by placing mulch

over the soil surface. The microclimate surrounding the plant and

soil is significantly affected by mulch i.e. the thermodynamic



yield. In order to maximize water and nutrient use efficiency by

the plant and to improve the quality of produce, the use of mulch

has become an important cultural practice in many regions of the

world for the commercial production of vegetable crops.

References


Date post:	14-Mar-2023
Category:	Documents
Upload:	iaas
View:	0 times
Download:	0 times

EFFECT OF PLASTIC MULCH IN VEGETABLES PRODUCTION

Documents