Leaf-water potential as a drought resistance character in rice

摘要

Drought significantly constrains higher yield and yield stability in rainfed rice. Maintenance of high leaf-water potential (#psi#_L) is associated with drought resistance, and water potential may be useful as an indirect selection criterion for improving drought resistance in rainfed rice. Rice is most sensitive to water deficit when flowering. We conducted three experiments to study (1) the genotypic variation in #psi#_L and its association with spikelet sterility under drought conditions: (2) the relationship between plant water status and delay in flowering among lines under different moisture regimes; (3) whether genotypic variation for #psi#_L was related to plant size and xylem anatomy: (4) the genotypic variation for water potential at given positions within the plant; and (5) the consistency of water potential across lines. The results of the field studies suggested that drought reduced #psi#_L and delayed flowering. The genotypic variation of #psi#_L for lowland was generally higher than upland stress conditions. The percentage of spikelet sterility of each genotype was positively associated with the delay in flowering time and negatively associated with #psi#_L under both lowland and upland stress conditions. Maintenance of water potential was not always related to plant size. Water potential varied according to the position within the plant, being lowest at the leaf tip and highest at the stem base. Variation in #psi#_L across lines was related to internal water conductance, xylem vessels and stem cross-section areas.