Interactions between Air and Root Temperatures on Greenhouse Tomato: II. Mineral Composition of Plants

Tomato plants ( Lycopersicon esculentum Mill. cv. Vendor) were maintained at 5 root temperatures (12°,18°, 24°, 30°, and 36°C) and 4 night air temperatures (12°, 15°, 18°, and 21°) for a period of 3 months. Although N content of the shoots was increased at 24° and 30° root temperatures, a reduction of this element was measured in the 4th fully expanded leaves. An increase in root temperature from 12° to 24° increased P, K, Mg, Ca, Fe, and Mn content of leaves, but had the opposite effect on Na. High night temperature (21°) favored the absorption of Ca and Na but reduced the concentration of P in the leaves. The results indicate that fertilization of tomato plants should be adapted to root and night air temperatures to avoid excessive vegetative growth and flower abscission and to maximize yield.