A genetic analysis of the number of cells,length of cell,and gibberellic acid sensitivity in sugar beet and their relation to bolting mechanism

Summary Three series of full-sib progenies and parental inbred lines or populations were used to study the inheritance of the number of cells and length of cell along the hypocotyl length, and the response to gibberellic acid in young plants of sugar beet. Variance components were determined by using a factorial cross design. There were no significant estimates of non-additive genetic variation for either cellular characters. Both additive and non-additive genetic variance were responsible for the variability of stem length after GA3 treatment. It is concluded that additive type genes predominantly control the number of cells in all series. The length of cell had significant additive variances in most cases, but it was indeed markedly influenced by environmental factors. Number of cells (cell division rate) and GA3 sensitivity in young plants even before vernalization were related to bolting tendency. Bolting-susceptible genotypes generally expressed higher stem length in the response to added GA3 as compared to the bolting-resistant genotypes. However, some genotypes bolted easily in the field but reacted weakly to the GA3 treatment and vise versa. Genotypes that were susceptible to bolting and/or sensitive to GA3 had a specific range (intermediate) of cell number. There were, however, some genotypes containing an intermediate number of cells which demonstrated low bolting. These responded faintly to gibberellin treatment. The results suggest that several physiological requirements have to be fulfilled before bolting can occur, and that other plant characters interfere with the bolting phenomenon.