FLOWERING AND TRUE SEED PRODUCTION IN POTATO (SOLANUM-TUBEROSUM L) .2. EFFECTS OF STEM DENSITY AND PRUNING OF LATERAL STEMS

Field experiments were carried out to evaluate the effect of stem density and pruning of lateral stems on flowering and true seed production in potato (Solanum tuberosum L.). Increasing stem density reduced flowering, berry and seed production from every inflorescence in all cultivars. Increasing density increased the proportion of primary flowers in the total number of flowers per plant and reduced the proportion of flowers on lateral stems, but its effect on the quality of the seed production was small. Differences in total seed production were principally determined by differences in flowering. There was an interaction between stem density and cultivars for the number of flowers produced and on the yield of true seed per m2. Pruning lateral stems enhanced flowering of the main stem and decreased the total number of flowers per plant, but it did not affect berry and seed production from main-stem inflorescences.