The effect of low night temperatures on carbohydrates metabolism in developing pollen grains of pepper in relation to their number and functioning

Abstract Four pepper cultivars were grown under winter low night temperature (LNT) conditions (night temperature of 10±2 °C and day temperature which did not exceed 24 °C) in a greenhouse in Bet Dagan, Israel. In all four cultivars, LNT conditions caused a decrease in the number of pollen grains and a reduction in their germinability, in comparison with pollen of control plants grown in another greenhouse under higher temperature conditions (night temperature of 20±2 °C and similar day temperatures). Analysis of carbohydrates content in the later stages of pollen development revealed that LNT caused a reduction in starch concentration 4 days before anthesis (A-4), and in the concentrations of sucrose and reducing sugars (glucose and fructose) at anthesis (A). It is suggested that low temperatures hinder pollen functioning in pepper, by interfering with starch accumulation at A-4, thereby decreasing the concentrations of soluble sugars in the mature pollen grains. The fruits of the LNT-grown plants, except for cv. Devilla, were smaller, seedless and misshapen. The reason for the ability of cv. Devilla to set seeds and normal fruits under LNT conditions need further investigation.