Selection efficiency of heading-time mutants in rice-role of environmental factors

Abstract

M2 populations of rice used in the present experiments originated from seeds of a Japanese cultivar, Harebare, treated with ethylene-imine and ethyl-methan-sulfonate. These plants were grown under different conditions in terms of planting time and amount of nitrogen fertilizer applied. Frequency distribution of M plants for heading time was affected by the planting time and the amount of nitrogen fertilizer applied. Selection efficiency for early heading of the M2 plants was the highest in the case of normal planting time, and the lowest in the case of late planting. Mechanisms controlling the changes in the selection efficiency for heading time are briefly discussed.