Photo-thermal Effects on Time to Flowering in Dolichos Bean (<i>Lablab purpureus</i> (L). Sweet) Var. Lignosus

Prediction of time to flowering of crop plants (especially photoperiod sensitive (PS) ones) help make appropriate crop management decisions such as choosing optimum sowing and harvesting dates which in turn determine plant size and thus affect dry matter production and crop yield. Modelling time to flowering of dolichos bean, a highly PS short-day food legume crop species, indicated greater role of temperature than photoperiod in regulating time to flowering of PS genotypes. The PS and photoperiod insensitive (PIS) genotypes of dolichos bean differed for base (Tb) and optimum temperature requirement for time to flowering. However, they were comparable for critical minimum, maximum and optimum photoperiod requirement for time to flowering. Dolichos bean requires critical minimum, maximum and optimum photoperiods of 11.11, 12.28 and 12.21 h respectively, and critical minimum growing degree days of 372.05°C day and optimum temperature of 23.13°C for time to flowering. Using average daily air temperature, and working backwards in time, it is possible to predict the combination of dolichos bean cultivar and sowing date that will produce ready for harvest crop on a predetermined day when fresh pod quality is optimal.