Effects of temperature and water-regime on the emergence and yield of tomatoes.

In pot experiments tomato seeds were grown at 9, 18 and 24 degrees C with soil moisture content 10 and 20 % below field capacity or brought to field capacity at the beginning of the experiment and never rewetted. Both temperature and water-regime influenced emergence but temperature had the more pronounced effect and the driest treatment at 24 degrees C gave higher percentage emergence than any at 18 degrees C. Seeds at 9 degrees C failed to emerge even after 42 days. In a second experiment, month-old tomato seedlings were grown at 35 degrees C day temperature and 18 degrees C night temperature or 20 degrees C day temperature and 15 degrees C night temperature under the same moisture conditions as before except that the driest treatments were brought to field capacity when the plants showed severe signs of wilting. Plants at 20 degrees C day temperature received only 80% of the incoming radiation that plants at 35 degrees C day temperature received. Plants with the 35 degrees /18 degrees C temperature regime and receiving most water gave the earliest yield, soon followed by those receiving the medium water treatment. Those in the driest treatment yielded much later. Plants under the 20 degrees /15 degrees C regime yielded in the same order and were all later than plants at the corresponding water treatments at the higher temperature. Plants in the higher temperature treatment had higher fresh weights of tems, leaves and fruit than those at lower temperatures but the latter were slightly taller probably due to the lower light intensity. (Abstract retrieved from CAB Abstracts by CABI’s permission)