Effects of decreasing VPD by misting on leaf area and leaf inclination in tomato and estimation of consequences on light absorption

During summer, in the Mediterranean regions, the yield of glasshouse tomato es declines. The present experiment aimed to determine whether severe clima tic conditions during this period of the year an responsible for this drop. The effects of reducing VPD in tomato were studied on leaf area from July to September and spatial leaf distribution and leaf angle distribution were determined in September. Plant leaf area in July was less than in Septembe r due to lower unitary leaf area. Misting increased leaf area and fruit yie ld in July, but had no effect in September. In September, misting favoured a heterogeneous distribution of leaf inclination, but differences in spatia l distribution and orientation of leaves had no effect on light absorption. We discussed the effect of misting on leaf area with contradictory results reported in the bibliography. Further measurements of plant architecture w hen the effects on VPD ale maximal (in July) are necessary to conclude on t he effects of VPD on estimated light absorption.