Effect of night humidity on the vegetative growth and the mineral composition of tomato and strawberry plants

Conditions of low night humidity (50–55%) and high night humidity (90–95%) were imposed on tomato plants (Lycopersicon esculentum Mill. cv. Young-Kwang) for 30 days, and on strawberry plants (Fragaria grandiflora Ehrh. cv. Bogyo) for 40 days. Shoot dry weight and leaf area in tomato plants increased with high night humidity whereas the strawberry plants did not show any such increases. The concentrations of five major nutrients (N, P, K, Ca and Mg) were reduced in tomato plants under high night humidity, with the calcium content in younger leaves being the most severely affected. For the strawberry plants, however, high night humidity tended to increase the concentrations of major nutrients, including calcium in the younger leaves. Possible reasons for the differences in response of these two species to night humidity are discussed.