Genotypic differences in plant water status and relationship with reproductive responses in snap bean (Phaseolus vulgaris L.) during water stress
2005
Omae, H.(Japan International Research Center for Agricultural Sciences, Ishigaki, Okinawa. Okinawa Subtropical Station) | Kumar, A. | Egawa, Y. | Kashiwaba, K. | Shono, M.
Eight genotypes of snap bean (Phaseolus vulgaris L.) were evaluated in a net house covered with polyethylene sheet under field conditions for their tissue water status and reproductive responses during water stress imposed at the pod formation stage. Leaf water potential (LWP) and relative water content (RWC) of the youngest fully expanded leaf from the top decreased in response to water stress and the extent of the decrease significantly varied among the genotypes. RWC was correlated with LWP in Haibushi, Kurodane Kinugasa, 45817, Ishigaki-2 and 3028520 but not in 86884, 92783 and Kentucky Wonder. Reduction in RWC with declining LWP was smallest in Haibushi, followed by 3028520, Ishigaki-2, Kurodane Kinugasa and 45817. Water stress reduced pollen fertility and the pod setting ratio. Relationship between the tissue water status and reproductive responses showed that the genotypes with a limited reduction-day RWC over morning or higher mid-day RWC displayed a higher pod setting ratio, irrespective of the pollen fertility. Therefore, the use of mid-day RWC as a physiological indicator for screening snap bean germplasm for drought tolerance may be further exploited.
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