Study on drought resistance in pigeon peas (cajanus cajan l. Hillsp)
Two experiments were conducted over two seasons. The f'irst "'experiment (Experiment I) ran from October 1979 to March, 1980 while the second experiment (Experiment II), which was a repeat ot experiment I,'was conducted between April and October, 1980. Both experiments were conducted in glass-house. Six genotypes of pigeon peas vere planted in 5 litre plastic pots such that there were two plants per pot. Planting medium consisted of a mixture of forest soil and cow dung manure in the ratio of 10:1 by volume. After one month of' growth the genotypes were subjected to four watering regimes: ,Watering daily to container capaci t;y, watering after every 7 days to container capacity, watering after every 14 days to container capacity, and watering after every 21 days to container capacity. These treatments were replicated in 5 blocks. The results showed that drought stress had depressing effect on plant height ,total plant dry weight, shoot dry weight, yield of grains per plant and number of pods per plant. Effects of drought stress on root dry weight, number of nodes per plant, number of branches per plant and number of grains per pod were not very clear but stress had little influence on lOO-seed weight. It was also found that water stress favoured deposition of dry matter in vegetative parts at the expense of pods. Of the vegetative parts drought· stress favoured roots more than shoots with respect to dry matter deposition. Genotypic differences were noted in both growth and yield attributes. Differences between seasons were remarkable in a number of cases and were attributed to differences in temperature between the two .seasons: Apparently two conclusions may be made from this study: (i) Pigeon peas in general are very resistant to drought but early maturing genotypes are more than late maturing ones although the latter perform better under wet conditions. The study of plant water relations in pigeon peas is influenced to a large extent by other environmental factors such as ambient temperature and sun-shine so that it would be difficult to isolate the direct effects of water stress under field conditions.