Soil moisture content
Plastic mulch is most efficient when used in combination with drip irrigation. Different mulching materials helped to perform better at water deficits. After providing irrigation either through drip or flood, the soil samples for moisture were collected two days after irrigation event. The moisture content of the soil at 5-10 cm depth was collected at three different locations in each treatment. Using the standard method (gravimetric) the soil moisture was estimated in three different stages of the crop and the average values are presented in Table 2. It can be seen from this table the soil moisture content for all the five treatments followed similar trend during the crop growing period, however, statistical analysis was carried out for moisture content values of 30 days after sowing and analysis is presented in Table 3.
All the drip irrigated treatments including different colored mulches
i.e., from T
2 to T
5 were found significant at 1% and 5% level of significance over flood irrigated treatment (T
1). Comparison of treatment means at critical difference of 5% indicated that the T
4 and T
3 treatments are significant over other treatments (T
1, T
2 and T
5), however there was significant difference in the soil moisture content values between T
4 and T
3 treatments. Similar trend was observed by
Gorden et al., (2010) in okra crop.
Soil and leaf temperature (°
C)
Chickpea is cultivated during
Rabi season in India, during which the night temperatures occasionally will fall as low as 2°C in Central India. During the experimental trial, frost event was occurred in the last week of December in the study area. The frost event coincided with the flowering stage of the crop and is detrimental for the crop. Soil and leaf temperatures (Fig 2) were monitored during the crop growing period on 30 days interval up to 90 days after sowing and were analyzed statistically and presented in Table 4 and 5.
All the treatments were found significant for soil temperature at 1% as well as 5% level of significance. Among the treatments T
4 was found significant as compared to T
1, T
2, T
3 and T
5 treatments. The trends were in agreement with the study of
Tegen et al., (2015) in capsicum crop.
The statistical analysis indicated that treatments were found significant at 1% and 5% level of significance. Among the treatments T
3 i.e., black colored mulch treatment was found more significant over all other treatments, this could be due to the fact that more solar radiation would be observed by black coloured mulch film as compared to other colours might have lead to increased temperature in the ambient micro climate of the crop (
Lamount, 2005).
Coefficient of uniformity
After assessing the Uniformity Coefficient under different heads
i.e., 2.0 m, 2.5 m and 3.0 m, the Chickpea crop was grown with an operating head of 3 m as this head resulted in maximum uniformity (94.2%) of water application. Since, the drip irrigation system adopted in the study is a gravity fed system, as the head decreases, the discharge of drippers at the farther points of laterals comes down. As a result the coefficient of uniformity of water distribution decreases with decreasing water delivery head. For 2.0 m head the value was 90.01% and at 2.5 m head the uniformity coefficient was 93.24%.
Growth parameters
Mulches significantly influenced the growth characters such as plant height, number of branches per plant, plant dry matter, effective nodules per plant and nodule dry weight (Table 6). The maximum plant height of 44.9 cm was observed under silver plastic mulch with drip irrigation and lowest plant height was recorded in flood irrigated crop (41.4 cm). Statistically significant plant height was observed under mulching in chickpea might be due to optimum availability of nutrients and moisture. At harvesting highest number of branches per plant and dry matter production were recorded in silver plastic mulch with drip irrigation. The lowest branches per plant and dry matter were recorded in flood irrigation. These findings are in agreement with the results reported by
Patidar et al., (2015) and
Singh (2016). Number of effective nodules per plant showed significant variation at 75 DAS of chickpea under different treatments. Silver plastic mulch with drip irrigation resulted in higher effective nodules per plant (28) and the lowest nodules were observed in flood irrigation condition (15). Drip irrigation along with plastic mulching facilitated better availability of nutrients in plants leading to higher number of effective nodules per plant. Mulches significantly influenced the nodules dry weight in silver plastic mulch with drip irrigation (57 mg/plant) as compared to black plastic mulch with drip irrigation (56 mg/plant) and lowest nodules dry weight was observed in flood irrigated condition (28 mg/plant).
Yield and yield attributes
In general, the drip irrigation method had higher application efficiency over conventional irrigation systems and supplies water to the root zone with a lower discharge rate not more than the infiltration rate of soil
(Ramaha et al., 2011). Maintenance of ideal moisture in drip irrigated treatments with mulch, resulted in better yield and yield attributes. Significantly higher number of pods per plant were recorded in silver plastic mulch with drip irrigation (326) followed by black plastic mulch (311) and lowest pods per plant were recorded in flood irrigation (28). Highest 100 seeds weight of chickpea was recorded under silver plastic mulch with drip irrigation (24.87 g) and lowest was recorded in flood irrigation condition (22.56 g). Treatments significantly affected the seed yield and harvest index with higher in silver plastic mulch and drip irrigation (2954 kg/ha and 49.68%) and lowest in flood irrigation condition (1740 kg/ha and 37.83%). Similar trend was observed in other mulch treatments
i.e., under black mulch and white mulch. Statistically significant results were obtained for these parameters in drip irrigated treatment also over flood irrigated treatment. However, the drip irrigated crop yield and yield contributing parameters are significantly lower when compared with mulch (black, silver and white) treatments. The higher seed yield under mulch treatments may also be attributed to reduced nutrient losses due to weed control and improved hydrothermal regimes of soil (
Singh, 2005,
Gangwar et al., 2017). The increased yield of chickpea under mulching conditions could be due to higher chlorophyll content with enhanced photosynthetic activity and higher uptake of nutrients (Table 7). This could have helped in increased plant dry matter production at pod setting phase, resulting in more number of pods per plant and finally contributed for higher productivity. These observations were in conformity with the findings of
Mahalakshmi et al., (2011) and
Akbar et al., (2011) in other legumes crop.
Water use efficiency
It can be seen from Fig 3 that the water use efficiency under silver color plastic mulch with drip irrigation recorded highest (17.21 kg/ha mm) followed by black color plastic mulch with drip irrigation (16.04 kg/ha mm), silver color plastic mulch with drip irrigation (17.21 kg/ha mm) and in white color plastic mulch with drip irrigation (14.81 kg/ha mm). The lowest value was found under flood irrigated condition (3.74 kg/ha mm). This could be due to the fact that the plastic mulch films prevent evaporation losses. This is in agreement with the results of
Kar and Kumar (2007) who reported significantly higher WUE in the straw mulched plots compared to the no mulched plots.
Economics
Drip irrigation system is generally adopted in horticultural crops which have high commercial value. Due to high initial investment in agricultural field crops, this system is seldom practiced. However, in the present study looking at the advantages of drip irrigation in terms of water saving, energy saving, quality produce
etc., experimental trial was taken up in Chickpea crop by adopting plastic mulching in drip irrigation. Economic analysis of the study was carried out to determine the economic feasibility of drip irrigation and plastic mulching in the cultivation of chickpea crop. The sale price of the chickpea seed considered was Rs. 40/kg looking at the wholesale market price.
Higher cost of cultivation (Rs/ha 80221) was recorded with plastic mulch as compared to other treatments (Table 8), whereas, the lowest was in flood irrigation (Rs/ha 36910). Higher net returns were recorded in silver colour mulch (Rs/ha 77939) followed by black colour mulch (Rs/ha 67179) and white color mulch (Rs/ha 55899). The higher gross returns in these treatments were due to higher seed yield as a result of higher moisture availability and better utilization of nutrients throughout the crop growth period. The lower net returns were obtained under flood irrigated treatment (Rs/ha 32690). The highest benefit cost ratio (1.97) was found for Chickpea cultivated in silver coloured mulch with drip irrigation system, followed by flood irrigated (1.88), black mulch with drip irrigation (1.83), white mulch with drip irrigation (1.69) and drip irrigation (1.51) treatments. The flood irrigated chickpea crop in terms of benefit cost ratio was found higher over two treatments of mulch (black and white) and drip irrigated crop. This is due to the fact that the cost of cultivation of involved in T
2, T
3 and T
5 did not commensurate with the yield values obtained under these treatments.