| dc.description.abstract | Wheat (Triticum aestivum. L), is one of the most important cereal crop grown in the world, which is consumed in more than 43 countries in the world. It is a major source of protein and carbohydrates in Africa and beyond. In Uganda, wheat is becoming an important crop and eaten in different forms including; bread, chapatti, spaghetti and other confectionary. The only form of wheat grown in Uganda, is bread wheat specifically the soft wheat which contributes about 30% in the processing of bread and the other portion is hard wheat. The use of inorganic fertilizers among other inputs is one of the ways through which wheat production and productivity can be improved. However, this faces a number of challenges including; escalating fertilizer prices, inadequate supply and differences in farmer resource endowments, lack sufficient knowledge on how to use these inputs more effectively and efficiently and lack of enough information on quality of wheat genotypes grown in Uganda. Uganda’s wheat production and fertilizer applications could be improved through optimization and efficient use of fertilizer nitrogen and phosphorus. However, optimum fertilizer rates for grain yield and quality and nutrient use efficiency needed investigation. As a result of the above scenario, a field experiment was conducted at BugiZARDI to establish the optimum nitrogen and phosphorus rates for grain yield, nutrient use efficiency and grain quality. Treatments included; four rates of nitrogen (0, 30, 60 and 90 kg N ha-1), three rates of phosphorus (0, 7.5 and 15 kg P ha-1) and three wheat genotypes (Fahari, Pasa and UW400). The experiment was replicated three times using a randomized complete block design with split plots.
Results show that, there was a significant (P < 0.05) interaction between genotypes with N and P combinations, in terms of number of tillers and grain yield. Total kernel weight and kernels per spike were significant for Pasa and UW400, respectively. UW400 emerged superior with grain yield of 3302 kg ha-1 which was 2.8% and 17.4% greater than that of Pasa and Fahari, respectively. Over all, the three genotypes attained maximum yield at 60 kg N ha-1 and 15 kg P ha-1 beyond which grain yield reduced. Agronomic nutrient use efficiencies were also significantly (P < 0.05) influenced by application of fertilizer N and P combination at different rates. Pasa showed the highest AEN obtained at 30 kg N ha-1 while UW400 showed the highest AEP at 7.5 kg P ha-1.
Wheat flour quality analysis was done on only UW400 wheat genotype due to laboratory and facility limitations. The effect of N and P fertilizer combinations on UW400 wheat genotype was significant (P < 0.05) for break flour yield only while, the single effect of N application was significant (P < 0.05) for starch only. Highest break flour yield was obtained at 60 kg N ha-1 and 15 kg P ha-1. Therefore, optimum application rates of 60 kg N ha-1 and 15 kg P ha-1 are recommended for best yield and break flour yield.
The Optimum combinations of N and P for best grain yield in the highlands of eastern Uganda, irrespective of wheat genotype, are 60 kg N and 15 kg P ha-1 and among the three wheat genotypes studied, UW400 responded best to N and P application. Pasa recorded the highest AEN of 25.8 kg kg-1 and this occurred at a low N application rate (30 kg N ha-1) and UW400 recorded the highest AEP of 124.5 kg kg-1, which occurred at a low P application rate (7.5 kg P ha-1). The best bread wheat quality was achieved with UW400 genotype at the application rates of 60 kg N and 15 kg P ha-1 in terms of break flour yield. However, application of N and P to the site soil has no effect on crude protein and starch contents of the grains of UW400 wheat genotype.
The areas for future research include; an economic analysis of the agronomic optimum rates obtained in this study to establish whether using them is profitable, the amount of amylose and amylopectin polymers which constitute damaged starch and gluten amounts important in wheat flour for bread should be investigated. | en_US |
