Effect of Transpiration Control Under High Salinity in a Greenhouse on Tomato Yield

For the reason of high concentration or high salinity in closed growing system, due to unbalance of supply and absorption of ions in nutrient solution, the response of tomato plants to high salinity was analyzed under normal and controlled climate (potential transpiration) in greenhouses. Two climate treatments, a reference (high transpiration, HET₀) and a “depressed” transpiration (low transpiration, LET₀), were combined with two salinity treatments in 4 pairs: salinity EC (electrical conductivity, mS/cm) 6.5, 8.0, 9.5 always coupled with a reference EC 2, and both EC 9 but a comparison of concentrated nutrients and nutrients with sodium chloride. It was shown that marketable fresh-yield production-efficiency decreased by 5.1% for each EC unit in excess of EC 2. The yield loss resulted from reduced fruit weight (3.8% per EC unit) and an increased fraction of unmarketable harvest because the number of harvested fruits was not affected. At the LET₀ treatment, yield loss was only 3.4% per EC unit in accordance with the reduction in fruit weight. Neither EC nor climate treatments affected individual fruit dry weight. It is concluded that transpiration control in a greenhouse have the same importance for tomato production as salinity control in root environment. And depressed transpiration may reduce the negative effect of high salinity on tomato yield.