Characteristics of postgermination growth of rice varieties suitable for anaerobic seeding with special reference to ethylene
1992
Herradura, P.S. | Yamauchi, M. (International Rice Research Inst., Los Banos, Laguna (Philippines))
Unstable crop establishment is one of the serious problems in wet-direct seeding. Recently, there are varieties which can establish on flooded soil (anaerobic seeding). This study clarifies physiological mechanism of the resistance of those varieties to low oxygen concentration. Seedlings (2-d-old) were incubated at various oxygen concentrations (0, 2, 21 percent) and their growth, endogenous ethylene production, the activity of ethylene-forming enzyme (EFE), and their reaction to exogenously applied ethylene were characterized. Coleoptile and mesocotyl elongations of the resistant varieties (RV) were greater than those of the control varieties (CV), especially at lower oxygen concentration. Root and 1st leaf growths were inhibited at 0-2 percent oxygen for both the varietal groups. Endogenous ethylene production and EFE activity were also inhibited at 0-2 percent oxygen. Exogenous ethylene, which could be present in the flooded soil, stimulated coleoptile and mesocotyl elongations more at 0 percent oxygen than at 21 percent oxygen. The coleoptile elongation of both the varietal groups were similarly increased by ethylene, but the mesocotyl of RV reacted more than that of CV, especially at 0 percent oxygen. These physiological characters of RV theoretically support the superiority in crop stand establishment from flooded soil
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