Division of Genetics, Indian Agricultural Research Institute, New Delhi-110 012
Forty-one dwarfs of spontaneous and induced origin have been studied for their response to GA3. On the basis of their differential response to 100 ppm dose, the dwarfs have been classified into eight different groups. Composition of each of these groups is in no way similar to any of the groups made on the basis of either D2 analysis or the nature of gene action governing height character. Significant differences in GA3 response of the dwarfs of comparable height suggest that the auxin-mediated height expression is probably governed by two or more sets of genes. The possibility of existence of additional/alternate pathways independent of GA3 biosynthetic pathway for height reduction cannot also be ruled out. Correlation studies between GA3 response and the average plant height at maturity show no significant and definite trend. The breeding value of the dwarfs such as TARI 7312 B’, TARI 5924’ and TARI 10560’ which have been identified as the least responsive to GA3 has been discussed.
