GENETIC VARIATION OF SOME TRAITS RELATED TO WATER DEFICIT STRESS TOLERANCE IN OATS

To determine the degree of tolerance to water stress deficit of some oats cultivars and to identify best traits of higher genetic variance related, a field experiment was carried out through two consecutive winter seasons in 2011-2013. That was on the farm of Dept. of Field Crops, Coll. of Agric., Univ. of Baghdad. Three depths of irrigation, 5, 7 and 9 cm (main plots), and three cultivars, Hamel, Pimula and Genzania (sub-plots) were used with RCBD in a split-plot arrangement. The experiment plots were watered 5 times from planting till physiological maturity to give seasonal water of 250, 350 and 450 mm Genzania cv. gave higher grain yield (5.16 t.ha(-1)) as average of both years, 121 d to flowering and 151 d to maturity. This cultivar gave 428 racemes.m(-2) , 30 mg. kernel(-1) and higher kernels.m(-2) (17800). Crop growth rate increased with increasing water. The depth of 5 cm gave 10.6 while depth of 9 cm gave 12.0 g.m(-2).d(-1). Irrigating the crop with 7 cm gave best results in raceme.m(-2) (419), kernels.m(-2) (18500) and grain yield (5.14 t.ha(-1)). The best combination of cultivars x irrigation depth was with Genzania cv. when irrigated with 7 cm, it gave 464 racemes.m(-2) and 5.67 t.ha(-1) grain yield. Increasing depth of irrigation from 7 to 9 cm disrupted source/sink relationship, so, harvest index decreased for increased total dry matter. Pimula cv. gave higher dry matter (18 t.ha(-1)) and lower grain yield. Irrigating with 250, 350 and 450 mm gave 17.6, 15.0 and 10.5 kg/ha grains/mm of water, respectively. Days to flowering and physiological maturity were characterized by higher ratio of genetic to environmental variance, and then harvest index and total dry matter. These three traits had 87% or higher h(b.s)(2). However, these traits had similar values of P.C.V% and G.C.V%. It was concluded that these four traits could be used for selection to improve water stress tolerance for this crop, and that water consumptive use of 350 mm.season(-1) is the best, and increasing water more than that will increase vegetative growth on the account of reproductive growth.