Water relation features of Juniperus excelsa M. Bieb under progressive soil drought stress of the Soutern Coast of the Crimea

Abstract

The dependences of the dynamics of photosynthesis intensity were studied, transpiration and temperature of Juniperus excelsa M. Bieb in the impact of soil drought and determined optimal and limiting conditions of growth of this species under the conditions of the Southern Coast of the Crimea. The display of photosynthesis response function to environmental factors allowed J. Excelsa to obtain numerical coefficients of nonlinear regression equations of these parameters. Optimal conditions are: Ws=65-75% FC, 1=700-1200 mkmol/m2s, Pn=10-12 mkmol/m2s. Changes in the intensity of net-photosynthesis and transpiration, net photosynthesis and estuary conductivity, escape diameter and soil moisture in the influence of soil drought are determined by regression statistics: for E and Pn R=0,90279, R2=0,81522; Pn and gsR=0,9028, R2=0,8152; Pn and gsR=0,9028, R2 =0,8152; dsh and WsR=0,9449, R2=0,8929 respectively. J. Excelsa has a high potential of photosynthesis for acclimatization to elevated temperatures. The increase in the temperature of the leaf (the khvoi) above the optimal leads to a sharp reduction in the intensity of photosynthesis the critical is the temperature of 39-40 degrees Celsius. With the introduction of this species to different regions, the results of the studies allow us to compare the ecological and physiological characteristics we have received with the climatic conditions of a particular region and to assess the possibilities of its cultivation.