تحت شرايط تنش گرمايي انتهايي HORDEUM VULGARE L مطالعه بعضي صفات كمي و واكنش زنوتيپ هاي جو لخت

Study of some quantitative traits and responses of hull-less barley(Hordeum vulgare L.) genotypes under terminal heat stress conditions

In order to study the effect of terminal heat stress on some quantitative traits and tolerance of five hull-less barley genotypes, an experiment was carried out at the Gachsaran, lran, on a silty clay loam soil, using a spill plot experimental design with three replications. Four sowing dates (Dec. 6 and Dec. 21 in 2000. and Jars 5 and Jan. 20 in 2001) were assigned to main plots and five hull-less barley genotypes (FICCO963, FICC 1570, FICC1571, FICC1725 and F1CC2712) to subplots. Results indicated that delay in sowing date decreased dry matter (16%), plant height (19%), grain yield (23%), harvest index (9%), numbar of days to flowering (11%) and number of days to physiological maturity (16%). Grain yield reduction was due mainly to reduced spike number per m^ʹ2 (12%), 1000 grain weight (16%) and duration of grain filling (30%). Genotypes showed different responses to terminal heat stress and the highest grain yield was obtained from FICCO963. Considering the stress tolerance index (STI), F1CC0963 had the highest grain yield under the optimum condition (4285 kg / ha) as well as under terminal heat stress condition (3361 kg / ha). It also performed to be resistant to terminal heat stress conditions, according to stress suseptibility index (SSI).