Characteristic water status in dwarf pea in relation to drought resistance

Abstract

Dwarfism in pea (Pisum sativum L.) manifests itself more conspicuously in the light, and light-induced epicotyl growth inhibition in relation to water status was studied. NMR spin-lattice relaxation times (T1)s of epicotyls of no-elongation zone were markedly longer than those of elongation zone of the seedlings of both cultivars, tall type cv. Alaska and dwarf type, cv. Progress No. 9. T1 of GA1-dose response in dwarf pea, which grows normally, decreased in elongation zone while T1s in no-elongation zone increased. The changes in T1 of light- and dark-grown pea epicotyls were not simply attributable to a change in water content. Water of dwarf control and no-elongation zone of GA1-treated cv. Progress No. 9 grown under light condition was more sustained during three-hours air drying compared to those of cv. Alaska. Osmotic concentrations in elongation zones were higher than those of no-elongation zone. In addition, there was no relationship between osmotic concentration and cell length. It seems that the epicotyl tissues of dwarf pea phenotype were high T1 values accompanied by low osmotic values while water uptake was not changed. In conclusion, T1 of the pea seedlings will be useful for an evaluation of the dwarfism and GA1 dose-response to drought stress.