RELATIONSHIPS BETWEEN VEGETATIVE GROWTH-RATE AND FLOWER PRODUCTION INFLAX

The physiological factors that regulate flower production are not well understood for flax (Linum usitatissimum L.) and other field crops, i n spite of the fact that flowers are directly related to seed yield th rough the fruits that form from them. The objective of this research w as to relate total flower production (FTOTAL), length of the flowering period (FPERIOD), and flower production rate (FRATE) of flax to (i) g rowth rates in several environments, and (ii) plant characteristics me asured before and during the flowering period. Growth, flower producti on, seed yield, and the components of yield of 18 genotypes representi ng three plant types were measured in five plantings (18 May 1984; 1 M ay 1989; and 2, 10, and 29 May 1990) at Brookings, SD. Differences in growth, flower production, and yield were large for the five plantings and small for genotypes grouped by plant type. Length of the vegetati ve period and concentration of N in the tissues at midbloom or last fl ower were the only traits with significant positive correlation for al l three flower production traits and all three plant types. Considerat ion of growth in shorter periods in three plantings showed that associ ations with FRATE, FPERIOD, and FTOTAL were negative for the vegetativ e period and positive for the flowering period for most plant characte ristics. Factors producing significant statistics in multiple regressi on with flower production traits included leaf weight or growth in lea f weight, length of the vegetative period, N concentration, total nons tructural carbohydrate (TNC) concentration, and stem weight. Path coef ficient analyses for FRATE, FPERIOD, and FTOTAL revealed indirect effe cts through leaf and stem growth rates for length of the vegetative pe riod and N concentration. We conclude that FRATE, which had been consi dered to be a growth function relating vigor during flowering to seed yield at harvest, may be adversely affected by rapid vegetative growth , and that similar effects may occur for FPERIOD and FTOTAL.