Effects of CO2 on greenhouse grown eggplant (Solanum melongena L.) II. Leaf tip chlorosis and fruit production

The effect of CO, on leaf boron content, Leaf Tip Chlorosis (LTC) and fruit production of eggplant (Solanum melongena L., cv. Cosmos) was investigated in the spring of 1991. Two levels of CO₂ (413 and 663 (xmol mol^-1) were maintained in duplicate, in four glasshouse compartments (16 m x 16 m). LTC was significantly more severe at high than at low CO₂. Leaf boron content was lower in leaves with LTC than in other leaves and was lower in leaves from high CO₂ than in those from low CO₂. These results, in combination with observed reduction in leaf conductance (part I), support the hypothesis that LTC is caused by reduced boron translocation to young, fast growing leaves, because of reduced transpiration. More specific research on boron is necessary to confirm this hypothesis. Fruit production was significantly higher (24%) at high CO₂ than low CO₂, despite more severe LTC.