Evaluation of plastic mulch effects on cucumber and tomato yields at flowering and production stages

Transcription

1 Proceedings of The Fourth International Iran & Russia Conference 805 Evaluation of plastic mulch effects on cucumber and tomato yields at flowering and production stages Behzad Ghorbani Assistant Professor of Irrigation Department, College of Agriculture, Shahr-e-Kord University, P.O. Box 115, Shahr-e-Kord, Iran. Phone: Abstract Plastic mulch is one of the effective ways to conserve water in the soil reservoir to be uptaken gradually by plants. Combination of plastic mulch and drip irrigation was popularized in the United State for more than two decades and recently in some parts of Iran, due to quicker to market benefit of faster seed germination and plant growth. However, the combination of plastic and furrow irrigation has not yet been fully examined in the field to find if there is any effect on soil water conservation and likelihood increase in the yield. The objective of this study was to find the effect of plastic mulch along with furrow irrigation on cucumber and tomato yield in the field at flowering and production stages. For this purpose, a series of experiments were performed in a field in Najaf Abad city in Esfahan province, Iran. Experimental layout consisted of three treatments: furrows without mulch, furrows conjunction with opaque (or clear) plastic mulch and furrows conjunction with black plastic mulch for both cucumber and tomato independently. Each treatment was replicated three times. The soil moisture content was monitored during the season and crops yield were estimated and the results were compared to control (furrows without plastic mulch). Overall, there was a significant difference in soil moisture retention between clear plastic and control and also between yields resulted from furrows with clear, black and without plastic mulches for both cucumber and tomato crops. Key words: Cucumber, furrow irrigation, plastic mulch, soil moisture, tomato, yield Introduction The rate of evaporation and water losses in agricultural area depends on a number of factors from which the irrigation methods are very important. Open ditches and flooded basins experience evaporation losses ranging from 10 to 40 percent (Vickers, 2001). The use of mulches helps conserve water, by reducing evaporation from soil surface, cooling soil, controlling weed growth, reducing soil erosion, and compaction (Robinette and Sloan, 1984, Thurston, 1997 and Vickers, 2001). The mulches compose of organic, inorganic (natural) and man made materials. Organic mulches are readily available, provide nutrients, and do not added chemicals to the environment (Robinette and Sloan, 1984 and Vickers, 2001). Budelman (1989) examined the impact of three types of organic mulches on surface soil temperature reduction and moisture conservation on a sandy soil (85% sand) during a 60-day dry period. According to him, the initial impact ranged from a reduction in soil temperature of 5.6 o C to 9.8 o C and an increase in soil moisture from 4% to 5.6% for different mulches applied in this experiment (Louise et al, 1999). Not all types of mulches are appropriate to be applied with any irrigation systems. For instance, natural or organic mulches slow down the water movement in surface irrigation,

2 Proceedings of The Fourth International Iran & Russia Conference 806 so, at least they are not suitable to apply for these types of watering. Drip irrigation systems are often effective when used in conjunction with any type of mulches, particularly with plastic mulches (Mata, et al, 2002). In contrast, plastic mulches can readily be used in conjunction with surface irrigation systems such as furrow irrigation to save water by reducing evaporation losses. Plastic mulches may be clear, black or any colure type. Short wave rays of sun penetrate in clear plastic warm up the soil (+10 o C) and the longer wavelengths re-radiating from the soil that is also trapped can intensify the situation. In this case, evaporating water causes green house effects that in turn increases early growth in cool season, but also stimulates weed growth under plastic. Black plastic is heated due to short wave absorption which in turn warm soil (+6 o C) by conduction and increases many crop yield and control weed growth (Robinette and Sloan, 1984). Canada-Saskatchewan Irrigation Diversification centre (2003) performed a series of research on vegetables such as cucumber and tomato planted on raised bed with black, clear and infrared trans-miss-able (IRT) plastic mulches. The results showed that clear mulch produced the earliest harvest and highest yields and provided the most favourable cost/benefit ratio. The vegetable yield increases obtained under black mulch as compared to bare ground were not always significant to justify the additional cost of material, installation, and removal of the mulch (Canada-Saskatchewan Irrigation Diversification centre, 2003). Plastic mulch seems to be one of the effective ways to conserve water in the soil reservoir to be up-taken gradually by plants. Plastic mulch is spread over the soil surface to trap the heat and accelerate the rate of soil warming and cause early harvest of crop product. Combination of plastic mulch and drip irrigation was popularized in the United State for more than two decades and recently in some parts of Iran, due to quicker to market benefit of faster seed germination and plant growth. To determine yield, quality, and water use efficiency (WUE) of muskmelon, six irrigation systems including drip and furrow with mulch on (Cucumis melo L. group Cantalupensis, Caravelle) were performed by Leskovar et al (2001). The results showed that the average water applied for drip systems was 53% lower than that for conventional furrow systems, and WUE was 2.3- fold as great. However, the combination of plastic and furrow irrigation has not yet been fully examined in the field to find if there is any effect on soil water conservation and likelihood increase in yield of cucumber and tomato crops. The purpose of this study is to find the effect of plastic mulch use with furrow irrigation on cucumber and tomato yield in the field at flowering and production stages. Material and methods Studies were conducted during the spring 2003 at a field located in the city of Najaf Abad (Latitude N; longitude E), Esfahan Province, Iran. Climatic condition in the city of Najaf Abad is semi arid with mild temperature and low rainfall during the fall, winter and early spring. Temperature is relatively high and there is rarely rainfall in late spring, summer and early fall. The experimental site consisted of clay loam in upper layer and sandy clay loam in the lower layer of soil. The physical characteristics of soil are shown in Table 1.

3 Proceedings of The Fourth International Iran & Russia Conference 807 Table 1 Soil physical characteristics of experimental site Depth (cm) Texture Bulk density (gr/cm3) Particle density (gr/cm3) Porosity Field capacity 0-10 clay loam clay loam sandy clay loam In early spring just prior to planting, 45 kg/1000 m 2 of complete fertilizer such as (N-P-K) were applied, worked into soil surface and returned to 10 cm. The experimental plots were furrows with 65 cm wide, 20 cm depth and 10 m long. The slope of furrows was Seedling of tomato (High Country variety) raised 10 cm were transplanted into the field at the beginning of April. At the same time, the cucumber seeds already germinated were planted. The plots were arranged in a randomized complete block with three replications for three treatments: furrows with clear and black plastics and without plastics. Seedlings were set on ridges at 20 cm spacing. When the plant crops started to flower, the furrow beds were covered with 0.2 mm thick clear and black polythene films (plastic mulch). At this stage water was applied to plots every 6 days. A sharp edged weir was used to measure the water requirement for site of experiments. Before irrigating the plots, the soil samples were taken from 10, 20 and 30 cm depth at the middle of each plot to determine soil moisture content using gravitational method. Soil moisture content measured immediately before and two days after each irrigation event. Table 2 shows the soil moisture deficit of plots for a period of six days. Soil water deficit of each experimental plot was computed using initial (θ i ) and final (θ f ) soil moisture contents by volume and depth of each soil layer as follows. 3 [1] SMD = ( θ i θ f ) D 1 where SMD is soil moisture deficit, D is the depth of soil layer, i and f indices are initial and final data. Table 2 Soil moisture deficit (SMD) for experimental plots (mm) Blocks Treatments Blocks mean Non plastic Clear Black plastic (control) plastic Soil moisture deficit, SMD (mm) sg 9.43 sg Soil moisture retention, SMR * Standard deviation, σ = 1.5 Notes: sg refers to treatments mean which are significantly different from the control. * SMR = [SMD(control)-SMD(clear or black plastic)] 100/SMD(control)

4 Proceedings of The Fourth International Iran & Russia Conference 808 A 2.65 m long segment from each plot was selected to harvest the crops yields for analysis purpose. First harvest of cucumber and tomato was performed on June 18 and August 4 respectively. Tomato and cucumber yields were harvested for 7 and 12 times respectively during the season. The crops yields are depicted in Table 3. Results and discussion The summary of soil moisture deficit (SMD) collected from field experiment is given in Table 2. SMD takes place, as water is lost through evapo-transpiration and/or percolation beyond the root zone. Soil moisture deficit was predicted using soil moisture content measured two and six days after irrigating the cucumber and tomato crops. According to this table, soil moisture deficit for furrows with clear plastic is lowest, as compared to that of furrows with non-plastic and black plastic mulch. In other words, the soil water retention (SMR) for clear plastic is 74.41% and for black plastic mulch is 7.19% more than that of furrows without plastic. So, there is a significant difference between the soil moisture content of furrows with clear plastic mulch and that of non-plastic mulch. Low quality black plastic might affect on low water conservation by this type of mulch. This is because of escaping of water vapour through the pores of low quality black plastic. Total cucumber and tomato crops productions are reported in Table 3. Analysis of variance showed that the mean yields of cucumber and tomato for furrows with both clear and black plastic treatments are significantly different from that of furrows without plastic treatment (at the level of 5%). This table also shows tomato mean production of 60.0 and 48.7 per cent higher than that of without plastic mulch treatment. There is also 65.8 and 46.7 per cent increase in cucumber mean production with respect to the mean yield resulted from the non-plastic mulched furrows (control). Table 3 Total Cucumber and tomato crops yield (kg/1000 m 2 ), obtained under three mulching treatments conditions Blocks Treatments Blocks mean Non-plastic (control) Clear plastic Black plastic Cucumber: Treatment mean sg 1237 sg Yield increase Standard deviation, σ = 40.0 Tomato: Treatment mean sg 1191 sg Yield increase Standard deviation, σ = Notes: sg refers to treatments mean that are significantly different from control (Non-plastic treatment).

5 Proceedings of The Fourth International Iran & Russia Conference 809 The reasons for significant differences in cucumber and tomato crops production for furrows with clear plastic mulch compared to that of control are likely due to the high soil water retention and/or nutrient conservation by clear plastic compared to black plastic treatment. Visual observation showed a high reduction in weed growth under black plastic mulch. But this was out of the objectives of this research that should be quantified. Conclusions The conclusions drawn from this research can be summarized as follows: 1- Using clear plastic mulch conjunction with furrow irrigation system had significant effect on soil moisture retention by 74.4%. No significant water conservation was considered under black plastic mulch in this study. 2- Considerable yield increments (60 and 48.7% ) and (65.8 and 46.7% ) were achieved for tomato and cucumber crops under both clear and black plastic mulches respectively at flowering and production stages. A more field study is recommended to understand the effect of furrow irrigation with plastic mulches on water conservation at growth, flowering and production stages under different climatic conditions. References Budelman, A., 1989 The performance of selected leaf mulches in temperature reduction and moisture conservation in the upper soil stratum, Agro. Syst., 8: Canada-Saskatchewan Irrigation Diversification Centre, 2003 Plastic Mulches for Commercial Vegetable Production ( Leskovar, D.I., Ward, J.C. and Sprague, R.W., 2001 Yield, quality, and water use efficiency of muskmelon are affected by irrigation and transplanting versus direct seeding HortScience, v 36, n 2, p: Louise, E.B., Lassoie, J.P. and Fernandes, E.C.M., 1999 Agroforestry in sustainable agricultural systems CRC Press, Boca Raton, New York, Washington, D.C., p: Mata,V.H., R. Nunez, E. and P. Sanchez, G., 2002 Soil temperature and soil moisture in Serrano pepper (capsicum annuum L.) with fertigation and mulching, Proceeding of the16 th International Pepper Conference, Tamico, Tamaulipas, Mexico ( Robinette, G.O., and Sloan, K.W., 1984 Water conservation landscape design and management, Van Nostrand Reinhold Company, Berkshire, England, p: Thurston, H.D., 1997 Slash/mulch systems - sustainable methods for tropical agriculture Westview Press, A Division of HarperCollins Publishers, Inc, Colorado, US, p: Vickers, A., 2001 Water use conservation Water Plow Press, Amherst, Massachusetts, US, pp: & 380.