The effects of temperature and photoperiod on times from sowing to flowering and maturity in a range of multi-purpose leguminous cover crop species have been investigated in controlled environments in order to quantify the photothermal coefficients which determine their potential environmental adaptation. Six genotypes representing six tropical or subtropical species were grown in 12 environments comprising all combinations of mean diurnal temperatures of 17, 22 and 27°C and photoperiods of 11.5, 12.5, 13.5 and 14.5 h day-1. Another six genotypes representing five temperate species were grown in nine environments comprising all combinations of 17, 22, and 27°C and photoperiods of 12.5, 13.5 and 14.5 h day-1. For all tropical and subtropical species, the warmest temperature combined with the shortest photoperiod hastened flowering and fruit maturity. However, except for Lupinus mutabilis which was photoperiod-insensitive, all temperate species both flowered and matured sooner at the warmest temperatures combined with the longest photoperiod. These photothermal responses in phenological development were amenable to modelling. Times to flowering were satisfactorily described using a general triple plane rate model. Rates of progress from first flowering to first mature pod were also satisfactorily modelled using temperature alone as the independent variable. These photothermal and thermal relations have identified considerable inter-specific differences in phenological responses to environment. The relations can now be applied to reveal the relative suitabilities of these diverse species as potential cover crops across hillside environments throughout the tropics and subtropics.
Field Crops Research (1998) 57 (2) 139-152 [10.1016/S0378-4290(97)00122-6]