Studies on water uptake and heat status of cherry root under water-saving measures

Abstract

This study investigated the effect of water-saving measures on the spatiotemporal variability of water absorption and thermal state in roots. It is crucial for understanding the process of water use of plants and its importance in the functioning of hydro-ecosystem. The spatiotemporal patterns of δ18O in the water from lower soil profile and the ratio of water absorbed by cherry roots from the soil at different depths and irrigation water, under four different treatment (CK, T1, T2, T3, i.e. 100 % of designed irrigation quota + no water-saving measures, 85 % of designed irrigation quota + no measures of water preservation, plastic film mulching and mulching by branches cut-off from the trees) were analyzed in the cherry orchard by measuring the stable oxygen isotopes (δ18O) in the soil moisture, sap in the xylem stem and in the irrigation water (local groundwater) under drip irrigation conditions during 2015−2016. The obtained outcomes show that the amount of δ18O in soil water is closely related to the changes in the irrigation, water-saving measures and soil moisture content during the growth stage of cherry trees. Irrigation significantly promotes the water absorption by cherry roots from soil water in the shallow layers. In the early growth stage of cherry trees, as the cherry grows, water absorption by cherry roots mainly comes from irrigation water. In the mid growth stage of cherry trees, if water-saving measures or adequate irrigation is employed, the contribution of soil water and irrigation water increases. In their mid-growth process, cherry trees mainly absorb water from the soil at a depth of 30−60 cm and irrigation water. Water-saving irrigation is beneficial to the utilization of irrigation water. After the harvest time, the cherries entered the late growth stage in August and September, where the cherries grow slowly and the amount of water required is low. At the same time, an increase in the temperature results in higher soil temperatures. Therefore, based on comprehensive consideration of the patterns of cherry water uptake and the characteristics of soil temperature during the cherry growth period. The best water regulation and management was 100 % of design irrigation quota and plastic film mulching at the fruit growth stage; 85 % of design irrigation quota and plastic film mulching at the postharvest stage; 85 % of design irrigation quota and no mulching should be applied at the end of growth stage.