Study of two ecogeographic groups of rice indicated larger embryo weight and length in japonicas than in indicas. Genetic variation is higher for embryo weight and embryo/endosperm weight and moderate for embryo length. Embryo weight correlated strongly with embryo length, kernel breadth and kernel thickness in two ecogeographic groups. Embryo length can be used to evaluate breeding materials for embryo size. In indicas, embryo weight and length correlated with seed and seedling vigour as measured by response to ageing stress, shoot length, root length and seedling dry matter. Both additive and nonadditive gene effects with preponderance of the former governed the inheritance of embryo length. Average dominance over all the loci across all parents was within the range of incomplete dominance. Combining ability also confirmed preponderance of additive gene effects in the inheritance of embryo size. Heritability estimates in narrow sense were very high.
Oryza sativa rice, embryo size, genetic variation, seed vigour, inheritance
