International Journal of Agriculture Extension and Social Development

This study was conducted during the winter growing time (2024-2025) at the Agricultural Research and Experimental Station of the College of Agriculture, University of Kirkuk. The experiment was arranged according to a split-plot system within a randomized complete block design (RCBD), with triple replications. The experiment fell into three main plots, which comprised foliar application levels of potassium supplied as potassium sulfate (52% K?O) at three concentrations (0, 10, and 20 g L?¹). Each subplot included thirteen oat genotypes, namely: Alguda, Anatolia, Pimula, Genzania, Hamel, Icarda Short, Kangaroo, Icarda Tall, Mitika, Possum, UC-132, Monte Zuma, and Cayuse. Each block contained 39 experimental units, to which treatments representing all possible combinations of the studied factors were randomly assigned. The quality traits of yield that were evaluated included crude protein (%), crude fiber (%), soluble carbohydrates (%), moisture percentage (%), and ash percentage (%). The results of the study can be summarized as follows: phenotypic variances were greater than both genetic and environmental variances for all traits, and genetic variance exceeded environmental variance at all potassium concentrations. The phenotypic and genotypic coefficients of variation ranged from low to high across the studied traits. For crude protein (%), the phenotypic, genotypic, and environmental coefficients of variation at the three potassium spraying levels (0K, K1, and K2) were generally moderate, while the phenotypic coefficient of variation was high at all concentrations except 0K. For crude fiber (%), the coefficients of variation were low at all three spraying levels. In the case of soluble carbohydrates (%), the coefficients were low at all spraying levels, except at concentration K2, where the phenotypic coefficient of variation was moderate. Regarding moisture percentage (%), the phenotypic and genotypic coefficients of variation were moderate at all three spraying levels, whereas the environmental coefficients were low. For ash percentage (%), the coefficients of variation were moderate at all three spraying levels, except at concentration 0K, where the phenotypic and genotypic coefficients were high.

Broad-sense heritability estimates were moderate to high for all studied traits under the three potassium concentrations (0K, K1, and K2). High heritability values were recorded for crude protein (%), crude fiber (%), and moisture percentage (%), reaching (0.835, 0.682, 0.751), (0.724, 0.724, 0.739), and (0.741, 0.906, 0.713), respectively. High heritability was also observed for soluble carbohydrates (%) and ash percentage (%) at concentrations 0K and K2, amounting to (0.630 and 0.791) and (0.884 and 0.694), respectively, while moderate heritability was recorded at concentration K1, with values of (0.560) and (0.504), respectively. As for the EGA expressed as a rate of the overall mean for the studied traits under the three potassium spraying levels (0K, K1, and K2), high values were obtained for crude protein (%) at all concentrations, reaching (46.42, 31.67, and 31.52), respectively. Similarly, ash percentage (%) showed high expected genetic advance at concentrations 0K and K2, amounting to (57.50 and 32.79), respectively.