Induction of some grain shape and morphological mutations in rice, variety IR-8

Abstract

The dehusked and presoaked seeds of rice ( Oryza sativa IR-8) were treated with 0·2 and 0·4 per cent ethyl methanesulphonate, and 0·003 and 0·005 m diethyl sulphate. Dry and dehusked seeds were also exposed to 20 kR of gamma rays. In the second generation the plants were screened for various morphological and grain size mutants. The induced morphological mutants include dwarfs, early maturing dwarfs, extreme tillering dwarfs, grassy dwarfs, plants with round grains and boat-leaf mutants. The grain type mutants varied from extremely round resembling japonica and indica varieties to long and slender in their shape and size. Mutants with translucent endosperm are being used in crossing programmes and also for studying the genetic basis of the “white belly” region in the IR-8 grains. Some of the promising fine grain mutants with IR-8 plant type and with improved milling and cooking qualities are already in the hands of a few progressive cultivators and will be released for commercial cultivation after further trials.