INFLUENCE OF ASSIMILATE SUPPLY ON LEAF FORMATION IN SWEET-PEPPER AND TOMATO

The influence of assimilate supply on leaf formation in sweet pepper a nd tomato was investigated. Assimilate supply for vegetative growth wa s varied by light intensity, by plant density and by fruit, truss and leaf pruning. In both species, a higher assimilate supply led to:an in creasing dry weight of the vegetative parts of up to 82%, whereas leaf appearance rate was hardly affected. Area of individual leaves was ha rdly influenced by fruit or leaf pruning, but increased with increasin g light intensity, decreasing plant density or the removal of every ot her truss. Increased assimilate supply resulted in an increase in dry weight of individual leaves and a decrease in specific leaf area. In a ddition, for sweet pepper grown under daylight conditions at a constan t 24-hour temperature, the rate of dry weight increase of total plant and vegetative parts changed considerably (coefficient of variation (C V) 0.52 and 0.44, respectively), but leaf appearance rate was rather c onstant during a growing season (CV = 0.07). It is concluded that, wit hin a large range, assimilate supply had little effect on leaf appeara nce rate during the generative stage of sweet pepper and tomato plants , whereas leaf size was affected.