CARBON ISOTOPE DISCRIMINATION, YIELD AND TRANSPIRATION EFFICIENCY IN BARLEY GROWN IN PLASTIC HOUSE

Abstract

The relationships among carbon isotope discrimination (?), transpiration efficiency (W) and yield were investigated in ten barley genotypes grown in a plastic house in pot experiment in northern Syria in two consecutive seasons (1990/91 and 1991/92). Four moisture treatments were used. A nonstressed treatment with soil moisture content near to field capacity (FC), a fully stressed treatment kept at 1/3 FC throughout the life cycle, a pre-heading treatment kept at 1/3 FC before heading and a postheadingtreatment kept at 1/3 FC after heading. Soil moisture contents were adjusted daily by weighing the pots and adding water. ? was measured in the peduncles at physiological maturity. Results show that ?, W, grain yield (GY) and above-ground dry matter production (AGDM) varied significantly with moisture level and genotype. Across moisture levels the relations between ? and yield (GY and AGDM) were highly significant and positive (r =0.85 and 0.82 respectively, P