Induction of Grain-size Mutations with Ethylenimine Treatment in Rice and a Comparison of Several Criteria for Screening Mutants

Abstract

For efficient screening of micro-mutations, it is an important problem to grasp the frequency and the direction of mutations exactly. In this paper, different statistical criteria were compared to estimate the frequency of the grain-size mutations induced by EI treatment (O.5%, 23.5°C, 2 hours) on three rice varieties; Arborio with large grain, Century Patna with slim grain and Amonoquilli with short grain. Increase of variances for the length and the breadth of grain in M₂ Suggested the induction of micro-mutations. Mean values in M₃ for both the characters tended to shift in minus direction. When aberrants are determined as the plants which fall outside the variation range of the control, the frequency of the aberrants for the length of grain was higher than that for the breadth. And the majority of the aberrants were for minus direction. Similar results were obtained from the stadardizing method which describes the theoretical frequency distribution curves.