Effects of Water Stress on Growth and Yield of Field-Grown Tomatoes I : Canopy Development and Biomass Accumulation

Abstract

In tomato plants subjected to different levels of water stress under field conditions of deep soils, it was found that drought had little or no effect on leaf water potential. However, biomass and leaf area developments were markedly depressed. Photosynthesis of the upper-most mature leaves was also affected, but this effect was largely attributed to leaf age; the dry treatment had older leaves with low photosynthetic efficiency. It was concluded that water stress depressed biomass accumulation mainly by inhibiting leaf area development. This occurred in two ways: first, through the reduced photosynthetic area arising from a small canopy, and second, since water stress depressed leaf area development, canopies of stressed plants consisted of a relatively large proportion of old leaves, which have low photosynthetic rates. This led to lower photosynthetic efficiency in such canopies.