Influence of assimilate supply on leaf formation in sweet pepper and tomato

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