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D.V. SRINIVASULU*, R.M. SOLANKI AND J.M. MODHVADIA
College of Agriculture, Junagadh Agricultural University, Junagadh, Gujarat-362 001.
A field experiment was carried out during rabi, 2010-11 to study the growth, yield, moisture extraction pattern and nutrient uptake in chickpea as influenced by irrigation and sulphur levels. Scheduling irrigation based on IW/CPE ratio and application of sulphur significantly influenced the growth, yield, moisture extraction pattern, nutrient uptake and quality of chickpea. Higher values for all these parameters along with net return and B : C ratio were obtained with scheduling irrigation at IW/CPE ratio of 0.9 which was statistically at par with 0.7 IW/CPE ratio. The study revealed that higher amount of moisture was extracted from surface layers irrespective of irrigation schedule and depletion of soil moisture by the crop increased with increasing frequency of irrigation. The highest water use efficiency was recorded under farmer’s practice of irrigation schedule, while the lowest was recorded with IW/CPE ratio of 0.9. Among the three levels of sulphur i.e. 0, 20 and 40 kg ha-1, application of 40 kg S ha-1 being at par with 20 kg S ha-1 recorded higher grain yield, net return and B : C ratio. But interaction of irrigation scheduled at 0.7 IW/CPE ratio with application of 20 kg S ha-1 recorded 32 % higher grain yield and higher B : C ratio over other treatment combinations.
B : C ratio, Chickpea, Chickpea, Irrigation, IW/CPE ratio, Sulphur.
Bengalgram or chickpea (Cicer arietinum L.) is the most important pulse crop of India accounting 34.6 per cent area and 48.4 per cent production of total pulses with
a productivity of 841 kg ha-1. Considering the climatic change, limited water resources and replacement of new varieties with earlier ones along with changing cropping patterns calls urgent need for application of water at an appropriate critical stage of the crop for ensuring better water use efficiency. Inspite of this, recent studies on soil fertility across the country showed that long term application of N, P and K fertilizers alone resulted in imbalance of nutrient ratios and led to sulphur deficiency in most of the states including the districts of Saurashtra region of Gujarat (Singh, 1999) and further, sulphur was known to increase the yield and quality in chickpea (Narendra Kumar et al., 2003). Due to very limited information regarding appropriate irrigation interval and optimum sulphur dose for chickpea crop in recent years in South Saurashtra region, the present investigation was carried out.
The field experiment was conducted at the Instructional Farm, Department of Agronomy, College of Agriculture, Junagadh Agricultural University, Junagadh during rabi, 2010-11. The soil was clayey in texture, rich in organic carbon (0.76%), low in available nitrogen (178.75 kg ha-1), potassium (112.90 kg ha-1) and sulphur (8.15 ppm), medium in available phosphorus (38.40 kg ha-1) and alkaline in reaction with pH of 7.9. The field capacity, permanent wilting point and bulk density of the soil were 28.4%, 12.8% and 1.36 Mg m-3, respectively.
The experiment was laid out in split-plot design comprising four levels of irrigation based on IW/CPE ratios [I1=0.5, I2=0.7, I3=0.9 and I4=farmer’s practice (1st irrigation immediately after sowing, 2nd irrigation at 10-12 DAS and rest of the three at an interval of 18-20 days)] were allotted to main plot and three levels of sulphur (S1=0, S2=20 and S3=40 kg S ha-1) allotted to sub plot treatments and replicated thrice comprising 36 plots each having a size of 5.0 m X 3.6 m. Sowing of chickpea (var. JG-16) was done using 60 kg seed ha-1 at a spacing of 45 cm x 10 cm. Irrigation was scheduled as per the treatments each at 50 mm depth measured with parshall flume of 7.5mm throat width placed at the head irrigation channel based on cumulative pan evaporation readings. Besides initial two common irrigations (1st immediately after sowing and 2nd at 10-12 DAS) a total of three (41, 60 and 82 DAS), four (33, 52, 68 and 80 DAS), five (29, 47, 57, 70 and 79 DAS) and three (29, 47 and 68 DAS) irrigations were given to I1, I2, I3 and I4 treatments, respectively. The quantity of water received by I1, I2, I3 and I4 treatments was 250 mm, 300 mm, 350 mm and 250 mm, respectively. Sulphur was applied to soil as per the treatments at 10 days prior to sowing in elemental form. Recommended dose of both nitrogen (25 kg ha–1) and phosphorus (50 kg ha–1) was supplied through Urea and DAP, respectively at the time of sowing. Depth wise moisture extraction and consumptive use of water by crop were studied by gravimetric method (Dastane, 1972). Observations on growth parameters, yield attributes, yield and quality were recorded.
Scheduling seven irrigations to chickpea (including two common irrigations) at IW/CPE ratio of 0.9 resulted in significantly higher plant height, plant spread, branches/ plant, dry matter accumulation at harvest, number of nodules and nodule dry weight/plant, pods/plant, seeds/ pod, test weight, grain and stover yield (Table.1). This was due to the availability of adequate moisture throughout crop growth and development contributing to luxurious uptake of nutrients, favourable physiological processes and active cell division. Increased frequency of irrigation from 0.5 to 0.9 IW/CPE ratio significantly delayed the flowering and maturity of the crop due to prolonged vegetative growth compared to farmer’s practice. The extent of increase in grain and stover yields of chickpea at 0.9 IW/CPE ratio was to the tune of 16.88 and 30.68% over farmer’s practice, respectively, and it remained at par with 0.7 IW/CPE ratio. The irrigation schedule of 0.9 IW/CPE ratio was exactly coincided with that of farmer’s practice and further provided two more irrigations one at peak vegetative stage and another at the time of maturity thus, resulted in more number of well filled pods with large sized seeds. This finally resulted in higher grain and stover yield. The results obtained by Patel (1988), Parihar (1990) and Dixit et al. (1993a) were in corroborative with the above results. Increasing frequency of irrigation from 0.5 to 0.9 IW/CPE ratio significantly increased the nutrient uptake by the crop.
Scheduling irrigation to chickpea at 0.9 IW/CPE ratio significantly increased the uptake of N, P, K and S by 20, 22, 18 and 27% and 41, 30, 37 and 43% by grain and
stover respectively over the farmers practice (Table.2). Continuous availability of adequate moisture resulting in more available nutrients in soil solution, active root and shoot growth, increased biomass accumulation, luxurious growth of root nodules along with synergetic effect between moisture, soil microorganisms and nutrients may boosted nutrient availability and resulted in higher uptake by chickpea crop at 0.9 IW/CPE ratio. These results were in close agreement with findings of Reddy and Ahlawat (1998) and Singh et al. (2004).
With increasing depth of soil, per cent moisture extracted by the crop gradually decreased. It was also revealed that about 60-64 per cent of moisture was extracted from top 0-30 cm soil depth and around 90-95 per cent moisture was extracted from 0-60 cm depth (Table 3). With increasing frequency of irrigation, the per cent moisture extracted from the upper layers increased. However, at lower IW/CPE ratios the moisture extracted from deeper layers was increased. The present study further revealed that increasing IW/CPE ratio from 0.5 to 0.9 increased total consumptive use of water and decreased water use efficiency (Table.4). This was due to more consumption of water resulting in higher vegetative growth and decreasing trend of yield increase per unit water available from lower to higher IW/CPE ratios. Same trend in moisture extraction, CUW and WUE were observed by Prabhakar and Saraf (1991) and Dixit et al. (1993b).
Application of 20 kg S ha–1 recorded significantly higher plant height and plant spread at harvest and was at par with 40 kg S ha–1. Whereas, dry matter accumulation at harvest, number of nodules and nodule dry weight per plant were significantly higher when chickpea fertilized with 40 kg S ha–1 and at par with 20 kg S ha–1 (Table.1). Increase in growth parameters with increased levels of sulphur was due to its higher availability and uptake as well as its active involvement in synthesis of amino acids, regulation of various metabolic and enzymatic processes along with enhanced nitrogen fixation and biomass accumulation. Similar results were reported by Singh et al. (2004) and Srinivasa Rao et al. (2010). Application of sulphur @ 40 kg ha–1 resulted in significantly higher number of pods per plant followed by 20 kg S ha–1 (Table 1). Joseph and Verma (1994) and Singh et al. (2004) reported
the same results. Maximum test weight recorded with the application of 20 kg S ha–1 followed by 40 kg S ha–1 (Table 1). Mishra et al. (2001) observed the same results at Raipur. Sulphur @ 40 kg ha–1 resulted in significantly higher grain yield and was statistically at par with 20 kg S ha–1. Whereas, maximum stover yield was obtained with 20 kg S ha–1 being on same bar with 40 kg S ha–1 (Table 1). This potential increase of grain and stover yields with increasing level of sulphur was due to it’s contribution on growth and yield attributes. Hariram and Dwivedi (1992) and Joseph and Verma (1994) reported higher grain yields in chickpea with 40 kg S ha–1. Significant increase in stover yields of chickpea with 20 kg S ha–1 was also reported by Srinivasa Rao et al. (2010).
Increasing levels of sulphur from 0 to 40 kg ha-1 significantly increased nitrogen, phosphorus, potassium and sulphur uptake by the crop. Application of 40 kg S ha-1 resulted in 12.4, 15.8, 12.6 and 19.8 per cent higher uptake of N, P, K and S by the crop, respectively over control and was at par with 20 kg S ha-1 (Table 2). This increase in nutrient uptake with successive increase in sulphur up to 40 kg ha-1 could be attributed to increased availability of sulphur to plants which in turn might have resulted in more number of effective root nodules, profuse shoot and root growth contributing to higher biomass production, higher photosynthetic activity as well as synergistic effect of N-S and S-P may boosted their availability and absorption from the soil. These findings were in accordance with those of Kaprekar et al. (2003) and Singh et al. (2004).
Significant trend in moisture extraction pattern was not observed with the application of sulphur. But it was showed that application of 40 kg S ha–1 markedly increased the WUE in chickpea (Table 3 and Table 4).
Interaction effect of irrigation and sulphur
Significant interaction between irrigation and sulphur was observed in number of nodules, pods and grain yield per plant, test weight and grain yield per ha (Table 1). Irrigating chickpea at 0.7 IW/CPE ratio along with the application of 20 kg S ha–1 resulted in maximum yield (Table.5). Interaction between irrigation and sulphur was also reported by Patel and Patel (2005) in chickpea.
Irrigating chickpea at 0.9 IW/CPE ratio resulted in higher net realisation as well as benefit cost ratio. Dixit et al. (1993a) also recorded higher net returns and B:C ratio at higher IW/CPE ratios. Fertilizing chickpea with 40 kg S ha–1 recorded maximum net returns and B:C ratio (Table 4). Results obtained by Singh et al. (2005) are also in conformity with the above results. But the present investigation revealed that combination of irrigating chickpea at 0.7 IW/CPE ratio along with the application of 20 kg S ha–1 resulted in maximum B : C ratio of 2.09 (Table 5).
The present investigation revealed that chickpea (cv JG-16) should be irrigated at IW/CPE ratio of 0.7 along with the application of 20 kg S ha-1 including recommended dose of fertilizers for higher grain yield in chickpea, net realization and higher B:C ratio under clayey soils of South Saurashtra agro-climatic zone.