Effects of Fertilizer Phosphorus on Yield Traits of Dekoko (Pisum sativum var. abyssinicum) Under Field Conditions

Cool-season food legumes (CSFLs) are important supplementary protein sources and soil fertility restorers for subsistence farmers in Ethiopia. Yields of CSFLs, however, are limited by low soil fertility, as they are grown in poor soils, often without fertilizer. Dekoko (Pisum sativum var. abyssinicum) is one of the CSFLs cultivated in Tigray, Northern Ethiopia. It is highly appreciated by the local people for its taste. This paper reports on the effect of phosphorus (P) on the yield and nutrition value of Dekoko under field conditions, and compares the results with those obtained for Ater (Pisum sativum var. sativum). The experiment was conducted in the 1998 and 1999 growing seasons. Three rates of P equivalent to zero, 30, and 60 kg ha P2O5 were tested. Biomass, leaf area index, branches ⁄plant, pods ⁄m and yield responded positively while seeds ⁄pod and seed weight were not significantly affected by P. Tissue P contents in shoots and roots increased with an increase in P application rate, while P in the nodules was not affected. Crude protein (CP) content increased from 24.9 % of dry matter (DM) at P0 to 26.2 % at P2, and from 24.3 % at P0 to 25.2 % at P2, in Dekoko and Ater seeds, respectively, while total sugars decreased with an increase in P application rate. Cysteine in Dekoko and asparagine 3,4 and threonine in both varieties decreased, while lysine and other amino acids were not significantly affected by P. P improved seed yield and CP content without greatly affecting the amino acid profile of Dekoko, when compared with that of the FAO ⁄WHO (1991, Protein Quality Evaluation. Food and Nutrition, Paper 51. FAO ⁄WHO, Rome) standard pattern of amino acid for children 2–5 years of age. Thus, improving yield through fertilization may help to improve nutritional quality and household food security for subsistence