EFFECT OF PREANTHESIS TEMPERATURE ON THE SIZE AND SHAPE OF SWEET-PEPPER (CAPSICUM-ANNUUM-L) FRUIT

The effects of pre-anthesis temperature on the size and shape components of fruits from three bell and two pointed-fruit type cultivars of sweet pepper were investigated in growth chambers, glasshouses and the field. Three temperature regimes of constant 18-degrees-C (low), 25-degrees-C/18-degrees-C, day/night (intermediate) and constant 35-degrees-C (high) were applied to plants at the third leaf stage through the third branching node formation. Thereafter, plants were allowed to grow either in a glasshouse maintained at 25-degrees-C/18-degrees-C, day/night temperature or in the open field until harvest. Large, medium and small fruits were obtained at the intermediate, high and low pre-anthesis temperatures, respectively. A high temperature increased the mean number of locule per fruit (shape component), in the five cultivars as compared with intermediate temperature. In the bell types, the number of four-loculed (tetralocular) fruits significantly increased, while that of three-loculed (trilocular) fruits decreased. A low temperature also resulted in a minor increase in the mean number of locules as a result of a slight increase in the number of tetralocular fruits; yet most fruits were unmarketable because they were short and blunt. The increase in the number of locules per fruit was associated with improvement in the blockiness of the bell type fruits, but not the pointed type fruits. Medium size blocky fruits, which meet the high market standards, were obtained at high pre-anthesis and intermediate post-anthesis temperatures.