Plant Breeding.
Parnell, F. R.; Rangasawmi, G. N.; and Ramiah, K. The Inheritance Characters ofRice. Mem. Agri. Dept. India. Bot. Ser. IX 2.
The authors find the simple ratio of 1 to 3 in several varietal characters of the grains and of the stem and leaves of paddy, e.g., long outer glumes in place of the usual very short ones ; a piebald arrangement of the dark colour of the furrows of the grain, as contrasted with its even distribution ; and similarly a piebald distribution of a golden colour of the inner glumes as contrasted with the full golden colour. This golden colour which appears as the grains ripen, in place of the more usual green ripening to a straw-colour is recessive to green. They find a purple pigmentation of various parts of the plant dominant over (the usual) green, the numbers of F 2 obtained being 41,121 to 13,664 or very nearly 3 to 1. But since in some crossings a ratio of 9 to 7 is obtained the colour is without doubt, they say, due to the simultaneous presence of two factors, one of which occurred in both of the varieties giving the first set of numbers in the ratio 3 to 1 in -F.2 ; while the varieties of the other set giving 9 to 7 were heterozygous to both. This fact was proved by the production of purple pigment in a cross between two pure strains both of which were green. A dark colour- ing of the pulvinus and auricle is similarly dominant over green. Other segregating characters are a purple striation of the internode, purple glumes, purple stigma and purple axil. Among these last they find 'coupling' occurred ; viz., purple striation with purple glumes, and purple stigma with purple axil ; while green internodes and glumes are associated with purple stigma and axil, showing a repulsion which proved to be between purple stigma and both purple striation and purple glumes. Though 60,000 plants were examined for this, no example of incomplete repulsion was recorded.
Another varietal character examined was a black colour of the inner glumes, which fades to a smoky colour when the grain is quite ripe. This colour is, as in so many cases, due to the combination of two factors. They find partial repulsion between both of these factors and that of purple striation of the internode.
Coming to the grain itself, inside the glumes, the red colour of some varieties was found to show the simple ratio of 3: 1, indicating dominance over its absence : but in two natural crosses with red rice some of the F 2 plants had a grey-brown colour. Though the experiments at the time of publication were not complete enough to prove it, the authors think chat this red colour is also due to the simultaneous presence of two factors.
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