Relative drought tolerance of major rainfed crops of the semi-arid tropics

Ten crop species were evaluated for their relative drought tolerance in seedling stage. Healthy seeds of each crop were planted in wooden boxes of 130 cm length, 65 cm width, and 15 cm depth filled with 3 soil types and watered daily. A week after germination watering was stopped and the reaction. of the plants of each crop to progressive water stress was observed. Based on percent dead plants at various time intervals and days taken to 100% dead plants for the ten crops, soybean appeared to be the most drought susceptible and cowpea was the most drought tolerant. The overall ranking of the crops in the increasing order of drought tolerance was soybean < blackgram < greengram < groundnut < maize < sorghum < pearl millet < bambaranut < lablab bean < cowpea. The water stress in the wooden-box method using higher sand content was too drastic for crops other than cowpea and lablab bean. With increased clay content and gradual water stress, it may be possible to use this method to detect varietal differences in crops like maize, soybean, pearl millet, sorghum etc., which are less drought tolerant than cowpea.