Response of Haricot Bean (Phaseolus Vulgaris L.) Varieties to Drought Stress at Different Growth Stages

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Drought is considered as the single most devastating environmental factor, which decreases crop yield more than the collective effect of other environmental factors. Varieties also differ in their reaction to drought stress, when they exposed to drought stress at different growth stages. Pot experiment was conducted at Hawassa College of Agriculture, southern Ethiopia, with objectives of identifying relatively drought tolerant haricot bean varieties and yield correlated traits under drought stress at different growth stages. Ten improved haricot bean varieties were subjected to drought stress by withholding water for 15 days at vegetative, flowering and pod-setting stages. The analysis of variance showed that phenology, growth and yield components were affected by both drought stress and varieties. However, their interaction effect was significant only for number of seeds plant -1 , seed yield and pod harvest index. Drought intensity indices at vegetative, flowering and pod setting stages were 0.046, 0.335 and 0.249 respectively. Drought at vegetative, flowering and pod setting stages reduces seed yield by 2.91, 33.53 and 25.11% respectively as compared to full irrigation. Plant height, branches, pods and seeds plant -1 and 100 seed weight were reduced most by the stress induced at flowering followed by pod setting stages. However, there was no statistical difference between the effects of drought stress at vegetative stage and full irrigation on all measured parameters. Varieties with higher yields under flowering stress were H/dumme (21.96g plant -1 ), Wajo(21.38g plant -1 ) and Nasir(17.45g plant -1 ) on the other hand Wajo (30.57g plant -1 ), H/dumme(22.6g plant -1 ) and Ibbado(30.45g plant -1 ) had better yield performance under full irrigtaion. Seed yield had significant and positive correlation with pod harvest index, days to maturity, number of pods on the main stem, seed plant -1 , 100 seed weight and plant height, which can be used as a selection index to screen drought tolerant haricot bean varieties. To achieve high yield, drought must be avoided during flowering and pod-setting stages, and varieties H/dumme, Wajo and Nasir can be recommended for drought prone areas. Keywords: Drought stress, drought tolerance, Phaseolus vulgaris L . DOI : 10.7176/JBAH/9-1-05