Effect of irrigation and cropping system on potato (Solanum tuberosum) grown sole or intercropped with French bean (Phaseolus vulgaris)

A field experiment was conducted on sandy loam soil analysing low in N and medium in P and K during winter season of 2004–05 and 2005–06 at Indian Agricultural Research Institute, New Delhi. The treatments comprised 5 irrigation levels (irrigation at critical stages of potato (Solanum tuberosum L.), irrigation at critical stages of French bean (Phaseolus vulgaris L.), and irrigation at 0.8, 1.2 and 1.6 IW/CPE ratio) as main plots and 3 cropping systems (sole potato, sole French bean and potato + French bean in 2:3 row ratio) replicated thrice in a split plot design. Irrigation at IW/CPE ratio of 1.6 produced the highest tuber yield followed by irrigation at 1.2 IW/CPE ratio, while the lowest tuber yield was achieved with irrigation at 0.8 IW/CPE ratio. Although the tuber yield with irrigation applied at critical growth stages (CGS) of potato was significantly lower than with IW/CPE ratio of 1.6, but the water use efficiency (WUE) with CGS of potato was higher. In French bean, both seed yield and WUE was higher with irrigation at CGS of French bean than that obtained with the irrigation at all the three IW/CPE ratios studied. Tuber yield of potato was higher in sole potato than when intercropped with French bean. Potato + French bean intercropping system recorded much higher B:C ratio (2.53) as against 1.54 with sole potato and 1.97 with sole French bean.