Plant Hormones Laboratory, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore-560 089
*Corresponding author. E-mail: kku@iihr.ernet.in
The effects of water stress imposed at flowering stage on the leaf relative water content (RWC), electrolytic conductivity and levels of polyamines and abscisic acid (ABA) in three cultivars of french bean differing in drought tolerance were studied. Amongst the cultivars, tolerant cv. Contender showed lesser decline in RWC and maintained stable electrolyte leakage than the susceptible cv. Arka Suvidha. The effect of stress on polyamines content depended upon cultivars and stress severity. Putrescine content increased under 3 and 6 days stress condition but declined under 9 days. Increase in putrescine was more prominent in susceptible cv. Arka Suvidha under 3 days stress and in the tolerant cv. Contender under 6 days stress. In the 9 days stressed plants, the decline in this polyamine was marked in the tolerant cultivar. The spermidine content showed a declining trend in all the cultivars following increased duration of stress, with tolerant cv. Contender showing lesser changes. In contrast, the spermine content increased progressively with stress in all the cultivars, and the tolerant cv. Contender maintained high levels in the stressed plants. The abscisic acid (ABA) content that increased gradually with increasing durations of stress showed a pattern similar to spermine. Putrescine and spermidine contents in stressed plants did not show any relationship with electrolyte leakage/RWC while spermine content was positively related to ABA content. The possible role of spermine in water stress tolerance has been discussed.
Abscisic acid, electrolyte leakage, french bean, polyamines, water stress
