LEAF FORMATION IN CUCUMBER (CUCUMIS-SATIVUS L) AS INFLUENCED BY FRUITLOAD, LIGHT AND TEMPERATURE

The time course of the leaf appearance rate in cucumber (Cucumis sativ us L.) was measured over an extended period. The effects of number of fruits per plant, light integral, and temperature on the leaf appearan ce rate, the area and weight per leaf, and the specific leaf area (SLA ) were also recorded. The leaf appearance rate on the main stem of a c ucumber plant increased with time until about 10 leaves had been forme d. Thereafter, it remained constant. When all fruits were removed, the leaf appearance rate per stem apex was the same, regardless of whethe r the plant had one or two stem apices. Decreasing the number of fruit s per plant greatly enhanced the leaf production rate per plant. Both the rate of appearance and the area and weight of individual leaves in creased. Moreover, removal of all fruits decreased the specific leaf a rea. The leaf area and the leaf weight production rates per plant were greater at 25-degrees-C than at 18-degrees-C because of the accelerat ed rate of leaf appearance. The area and weight of individual leaves w ere less and the SLA was larger at 25-degrees-C than at 18-degrees-C. Although the number of fruits per plant increased at increasing light level, the SLA decreased, but the number of leaves, the area and weigh t of individual leaves and the total leaf area per plant increased. A predictive model of crop growth should take into account the effects o f the age of a plant, the number of fruits on a plant, the temperature and the light intensity on leaf appearance rate and the size of indiv idual leaves.