Relationships between Vegetative Growth Rate and Flower Production in Flax

Abstract

The physiological factors that regulate flower production are not well understood for flax (Linum usitatissimum L.) and other field crops, in spite of the fact that flowers are directly related to seed yield through the fruits that form from them. The objective of this research was to relate total flower production (FTOTAL), length of the flowering period (FPERIOD), and flower production rate (FRATE) of flax to (i) growth rates in several environments, and (ii) plant characteristics measured before and during the flowering period. Growth, flower production, seed yield, and the components of yield of 18 genotypes representing three plant types were measured in five plantings (18 May 1984; 1 May 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 vegetative period and concentration of N in the tissues at midbloom or last flower were the only traits with significant positive correlation for all three flower production traits and all three plant types. Consideration of growth in shorter periods in three plantings showed that associations with FRATE, FPERIOD, and FTOTAL were negative for the vegetative period and positive for the flowering period for most plant characteristics. Factors producing significant statistics in multiple regression with flower production traits included leaf weight or growth in leaf weight, length of the vegetative period, N concentration, total nonstructural carbohydrate (TNC) concentration, and stem weight. Path coefficient analyses for FRATE, FPERIOD, and FTOTAL revealed indirect effects through leaf and stem growth rates for length of the vegetative period and N concentration. We conclude that FRATE, which had been considered 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.