| heal.abstract |
A reliable prediction of flowering time of forage legumes is an important factor which determines management decisions in order to optimize production and utilization. The experiments, were conducted during two successive growing seasons, following a split plot randomized complete block design with three replications, seven main plots (sowing dates) and two sub-plots (sulla and Persian clover). Linear models were used to relate the rate of progress towards flowering (1/f) to mean air temperature and mean photoperiod from sowing to early and full flowering. Evaluation of flowering time was also based on days after sowing (DAS), day of year (DOY-age in days from 1 January), growing degree days (GDD-amount of heat units above a species-specific base temperature), photothermal index (PTI) and photothermal time (PTT). Temperature and photoperiod strongly affect time to flowering, but not in the same way for the two species. The thermal and photothermal models accounted for most (80-85% and 82-87% respectively) of the variation observed in time to flowering for the two flowering stages. The responses of 1/f to temperature were significant for the two species, whereas the sensitivity to photoperiod was significant only for sulla. Time to reach early and full flowering was best correlated with DAS and DOY for sulla, while DAS and GDD predicted more accurate flowering time for Persian clover. GDD or PTT for sulla and DOY or PTI for Persian clover were not as highly correlated with dates to reach both flowering stages. |
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