GRAIN-YIELD IN DETERMINATE AND INDETERMINATE CULTIVARS OF VICIA-FABA WITH DIFFERENT PLANT-DISTRIBUTION PATTERNS AND POPULATION-DENSITIES

A determinate and an indeterminate cultivar of Vicia. faba were grown in the field to study the effects of two different plant densities and three plant distribution patterns on yield formation. The relationship between crop growth rate during flowering and the number of pods produced was identical in both cultivars. The higher growth rates of the indeterminate cultivar and of dense stands were associated with higher pod numbers. Average crop growth rates in the period between flowering and 30 days thereafter were related to the number of mature seed-containing pods. This relationship was similar in both cultivars except that the determinate cultivar aborted seed-containing pods as late as 40-45 days after flowering when grown at the low density. Rates of seed filling for both cultivars were similar at the low density (c 1.4 mg per degrees-C per day per pod), but were larger for the determinate cultivar at the high density. The annual differences in seed weights per pod were not related to seed filling rates. Grain yields and harvest indices were generally lower in the determinate than in the indeterminate cultivar, but high plant density increased seed yields of the determinate more than of the indeterminate, because of an increase in harvest index. Plant distribution pattern had no significant effect on the above characters.