Effects of genotypes and potassium rates on some of cowpea traits heritability

Abstract

Background: Introduction is considered one of important plant breeding methods to develop new cultivars. Cowpea cultivars have high performance under optimum potassium level because of their positive effects on photosynthesis and physiological as well as chemical processes in plant. Methodology: Two cowpea cultivars (byader and bonanza) and their F5 progenies were planted at Abu-Ghraib station located in Baghdad in the middle of Iraq in the autumn season, 2014. Split plots in randomized completely block design was used. Potassium rates were control (without application), 50 and 100 kg K ha-1 were assigned to main plots while genotypes occupied the sub-plots. Statistical analysis of variance to test the significance and to measure the least significant differences between means was carried out. Results: Byader was superior in 100 seeds weight, pod length and seeds number per pod. Byader F5 recorded lowest mean in days to flowering, number of pods per plant and seed yield. Bonanza F5 and byader had the highest mean in seeds number per pod. Plants grown at 100 kg K ha-1 took the shortest period to flowering. Byader F5 grown at 100 kg K ha-1 was the best for early flowering. In addition, it was the highest in pod length, pod number per plant and seed yield. Bonanza F5 was the best in seeds number per pod. Strongest positive correlation relationship was r = 0.919 between seed yield and pods number per plant, therefore, it considers as a strongest indirect selection index to improve seed yield. High heritability value was 80% for 100 seed weight because of strong genetic control on it. Similarly, it was observed with inheritance of days to flowering. Small differences between genotypic coefficient correlation (GCV) and phenotypic coefficient correlation (PCV) was recorded, indicating high homogeneity between plants. Conclusion: Selection in early generation for pods number per plant led to high seed yield in cowpea progenies F5 especially when planted at optimum rate of potassium fertilization.