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Desiccation of leaves after de-submergence is one cause for intolerance to complete submergence of the rice cultivar IR 42

Setter, Timothy L., Bhekasut, Panatda, Greenway, Hank
Functional plant biology 2010 v.37 no.11 pp. 1096-1104
plant damage, cultivars, rice, plant growth, relative humidity, Oryza sativa, flooding tolerance, seedlings, leaf water potential, flooded conditions, desiccation (plant physiology), leaves
This paper presents evidence that severe water deficits, following de-submergence after flash flooding of rice, contribute to submergence intolerance of IR 42, a rice cultivar that rapidly elongates during submergence. In glasshouse experiments, 13-day-old rice seedlings were completely submerged for 3-5 days. The main experiments were with IR 42, a cultivar intolerant to transient complete submergence. During submergence the 3rd leaf expanded, and after 5 days submergence its sheath was 4-fold longer than in non-submerged seedlings. After de-submergence, this leaf rapidly desiccated, its water potential dropped below -2MPa, while the stomatal conductance was very low. Excision experiments showed the water deficits after de-submergence were due mainly to a large reduction in the hydraulic conductivity in the leaf sheath. The water deficits are an important cause in the sequence of events rather than a mere result of injury: when plants were de-submerged at 100% rather than at 50% RH, water potentials remained high. However, when, after another 5 days, these plants were transferred to 50% RH, the 3rd leaf rapidly desiccated, indicating little repair of the lesion causing the low hydraulic conductivity.