Water deficits and yield in upland rice

Abstract

Few data are available relating leaf water potential to yield and yield components. In field conditions, ascertaining leaf water potential at high frequency is both laborious and detrimental to crop stands. Leaf water potential and six soil and climatic descriptors related to the crop water status were monitored in an upland rice farmer's field in the Philippines. Soil matric potential at 15 cm depth and daily total evaporative demand were used to predict daily minimum leaf water potential of the three rice cultivars grown. Difference among rice cultivars for leaf water potential response to soil and atmospheric water status was noted. Establishing −17 bars as a critical leaf water potential allowed determination of degree, duration and degree × duration values of water stress during yield determining growth stages. Results verified the relative lack of yield sensitivity to vegetative stage water stress and the high sensitivity of the reproductive stages. Decreased yield, increased sterility and decreased grain weight were associated with degree and duration of water stress occurring at particular developmental stages.