Effects of air temperature, soil temperature and soil moisture on growth and development of tomato itself and grafted on its own and egg-plant rootstock

Abstract

The problem was studied whether tomatoes, grown in a hot and arid climate, benefit from grafting on egg-plant, which is highly efficient in water uptake. Growth and development of tomato ( T), tomato grafted on its own rootstock ( T T ) and tomato grafted on egg-plant rootstock ( T E ) were compared at air temperatures of 28°C during the day and 18°C during the night ( 28 18 ) and at 28°C constantly ( 28 28 ), at soil temperatures of 14, 21 and 28°C with the following soil moisture regimes: wet ( W 1), medium ( W 2) and dry ( W 3). At 28 18 and 28 28 water consumption was about equal, but the transpiration ratio at 28 28 was twice as high as that at 28 18 . The latter conditions gave a much stronger plant with more fruits. At a soil temperature of 14°C water use was strongly reduced. The transpiration ratio increased with the soil temperature. Differences in plant type were small. At the highest soil temperature of 28°C fruit growth was strongly reduced. At lower soil moisture levels less water was used and the transpiration was lower. Plant type was correlated herewith. Vegetative growth of T T was weaker than of T, but generative growth was stimulated. The strong E rootstock stimulated vegetative growth at high air and soil temperature, but fruit growth was very poor under these conditions; at a low soil temperature of 14°C vegetative growth was also reduced. The hope that the E rootstock would be beneficial for fruit growth at high temperatures was not fulfilled. An additional experiment in a growth-room at 23°C showed that under conditions of moisture stress there was no difference in water potential between leaves of T T and T E .