Interactive effects of supplemental irrigation and planting arrangement on yield and water use efficiency of chickpea (cv. Arman) in Gonbad

In order to study the effects of supplemental irrigation and planting arrangement on yield, yield components and water use efficiency (WUE) of Kabbuli chickpea (cv. Arman), an experiment was carried out at the Agricultural Research Station of Gonbad for two years, Iran. The experiment was a split-plot factorial arranged in a Randomized Complete Block Design with three replications. The main plots consisted of four irrigation applications: once at the flowering (I1), once at grain filling (I2), twice, one at the flowering and one at grain filling (I3), and rainfed condition (RF). Combination of planting densities (20, 32 and 44 plants per square meters) and rows spacing (25 and 50 cm) were as sub plots. The combined analysis results revealed that all traits were significantly affected by year. None of the traits studied were significantly influenced by simple effects of irrigation or row spacings. All the traits, but 100 grain weight and number of grains per pods were significantly affected by irrigation and row spacings interaction. The effect of irrigation on seed yield did not follow the same trend in two years. In the first year that sum of rainfall was low, RF and then I2 with 3.2 and 2.5 (t/ha), 8.3 and 5.1 (Kg seed/mmwater.ha) and 46.0 and 38.4 (%) and in the second year with I2 with 2.1 (t/ha), 4.0 (Kgseed/mmwater.ha) and 28.7 (%) had the highest seed yield per hectare, WUE and harvest index, respectively. It shows the importance of the time when the rainfall occurs. Therefore based on the increase in yield, irrigation at grain filling might be suitable. Twenty five-centimeter-wide rows out yielded the 50-cm-wide rows in both years. In the fist year, decrease in row spacing significantly inceased grain yield around 400 kg /ha. In the second year, 20 plants m-2 produced higher yield than those of other plant densities.