Flowering and Seed Production of Centrosema spp. in Relation to Day Length and Temperature

The effcc1s of variation in daylength and temperature on the flowering processes leading to seed production were studied in genotypes of 5 Centrosema spp. Short days (11 h) enhanced flowering in accessions of C. virginatum from low latitude but flowering of lines from high latitude was more prolific in 16-h days. A quantitative long-short day response was evident in 2 intermediate latitude accessions. The critical photoperiod for flowering·varied: C. virginianum cross 31 flowered in 13.5 h or less, C. pubescens, C. pascuorum and C. macrocarpum in 12 h or less, and C. schiediam Oowcred only in a 10.5 h treatment. High (33/28°C, day/night} temperature suppressed flowering and increased floral abortion in long but not short days. A requirement for short days for continued flowering after first flower appearance was demonstrated. Plower number and flower setting were the components of seed yield more sensitive to climatic variation than seed number/pod or 100-seed weight.