Evaluating Water Stress in Wheat Using Carbon Isotope Discrimination and other Crop Physiological Indices in the Central Anatolia Region of Turkey

摘要

A study was carried out between 2009 and 2011 to evaluate the effect of different irrigation regimes on the carbon isotope discrimination (A~(13)Cs) in leaf and grain samples, and the crop water stress index (CWSI), as indicators of water stress for wheat crop. The objective was to determine the relationship between CWSI and A~(13)Cs under field conditions and to calculate water-use efficiency (WUE [grain yield per unit evapotranspiration (ET)]) for wheat under different irrigation regimes (no irrigation, full irrigation, moderate and high water stress). The experiments were conducted at the Saraykoy Research Station in the Ankara-Murted Basin. Soil water content was measured with a neutron probe; while wheat canopy temperature and stomatal conductance were measured using infrared thermometer and porometer, respectively. The results suggest that water stress affects canopy temperature and stomatal resistance of the crop. Average canopy temperature was inversely correlated with stomatal conductanceand can be used as indicators of stomatal closure in response to soil water deficit. The CWSI which is an index based on canopy surface temperature, is a promising tool for quantifying crop water stress. Carbon isotope discrimination values showed that grain and leaf A~(13)Cs can be used for selecting high wheat grain yield under water-limited conditions. Irrigating after-heading period is recommended to increase the WUE of wheat in the central Anatolia region of Turkey.