The influence of some environmental factors on growth and development of Sesamum indicum L.

The influence of light and temperature on vegetative and reproductive development of sesame varieties was studied.

Stem growth and leaf production in growth chambers increased as average temperature was raised from 24° to 33°C; alternating day and night temperature were not beneficial. Lengthening the daylight period and extending daylight with fluorescent light (intensity 2000 erg sec ^-1cm ^-2) increased stem length, number of leaves and leaf size.

Seedlings were not sensitive to length of the photoperiod for 3 to 8 days after emergence, according to variety. A constant temperature of 24° to 27°C was optimum for early floral initiation.

Photoperiodic response was studied at photoperiods ranging from 5 to 24 h, consisting of a basic illumination of daylight supplemented by different periods of weak fluorescent light. The number of days to floral initiation and flowering was minimum with a photoperiod of 10-13 h, of which at least 8 h was daylight. The delay with photoperiods shorter than 10 h was mainly caused by restriction of photosynthesis. In most varieties flowers were eventually initiated even with photoperiods of 20-24 h. More flowers and capsules were produced as the photoperiod, irrespective of its composition, was lengthened from 6 to 20 h.