On the Response of Water Stress of Selaginella tamariscina under Dry Conditions

Abstract

When plants are planted on the gradient of a sloping roof, it is necessary to keep the substrate material as lightweight as possible. However, small quantities of substrate tend to dry easily and are thus unfavorable for plant growth. Consequently, new planting materials need to found that will work well even in suboptimum environmental conditions.In the present study, we used Selaginella tamariscina to test the ability of this species to withstand drying and the recover from water stress. Plants were subjected to three diurnal / nocturnal temperature regimes of 20 / 15, 25 /20 and 30 / 25°C, respectively. We studied the form of the plants and the changes in leaf water potential after the restriction of water supply. The results showed that the onset of water stress, measured as a decrease in leaf water potential, was positively correlated elevated temperatures. The number of days taken for leaves to assume the shape of a fist was 20 days at temperature conditions of 20 / 15 and 25 / 20°C, respectively. However, at 30 / 25°C this process only took approximately eight days. Recovery of specimens took approximately one day at 20 / 15 and 25 / 20°C when resupplied with water ; even in instances where water had not been supplied for 150 days or more. Conversely, in the 30 / 25°C temperature range, recovery was observed to be slightly delayed after resupplying with water, and recovery was not possible in instances where water had been withheld for 120 days.