Flowering Responses of Some Palestinian Legumes to Photoperiod and Temperature

A LATE autumn outdoor sowing was made of eighteen species of wild-growing leguminous annuals. As soon as the seedlings were big enough to handle, they were potted and grown under fixed photoperiods of 9, 12, 15 and 18 hr., and at natural day-length, in a heated greenhouse in which the temperature was thermostatically maintained above 14° C. A parallel outdoor control series, comprising the genera represented by more than one species, was exposed to lower average temperatures, with minima frequently amounting to only a few degrees above zero. Each treatment lot consisted of five replications. The natural day-length diminished during the experimental period from 11 hr. 15 min. to the annual minimum of 10 hr. 25 min., and then went up again to just under 12 hr. by the time all flowering was over on the greenhouse plants. Observations on the outdoor plants were continued until May 1, when the length of day was 13 hr. 25 min.