Abstract
To examine the effects of low temperatures on flowering of Lathyrus latifolius L. under long day conditions, various temperatures were applied to imbibed seeds or seedlings for various duration and then grown in a greenhouse kept above 15°C and under 16 h day length. Exposure of imbibed seeds to low temperature of 1°C for 30 days had no effect on flowering in ‘Pink Pearl’, ‘Red Pearl’ and ‘White Pearl’. When seedlings of ‘Pink Pearl’ were grown in a greenhouse kept at 15–25°C for 6 months then exposed to temperatures of 1, 5, 10 and 15°C for 8 weeks, days to flowering and nodes to the first flower were reduced and number of florets of the first inflorescence was increased in plants raised from seedlings exposed to 1 or 5°C. Subjecting seedlings to 5°C for more than 8 weeks was necessary to promote flowering. A growing period for more than 110 days was needed to respond to the low temperature treatment. When plants were exposed to natural low temperatures for 0, 30, 60, 90 days and then grown under four photoperiods (10, 12, 14, 16 h) in the glasshouse kept above 15°C, the flowering percentage did not change under a day length of 10 or 12 h irrespective of the length of exposure to natural low temperature. This finding indicates that the qualitative long day requirement for flowering remains unaltered even in plants that received natural low temperatures for 3 months.
