Genotype and Nitrogen fertilizer influence on Grain yield and protein content of wheat(Triticum aestivum L.)

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Makhale, Gerard Lekula
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The grain yield of wheat in Lesotho is low because of poor soil fertility, and the wheat is regarded by the millers to be of poor quality and therefore of less value. A field study was therefore conducted at three sites in Lesotho( Maseru, Leribe and Mafeteng) to evaluate the influence of genotype and nitrogen application on grain yield and quality of wheat (Triticum aestivum L.) The varieties assessed were Tugela DN, Betta DN, SST 124 and caledon at a seeding rate of 50kg ha-1. Nitrogen was applied at five rates of 0,20,40,60, and 80 kg N ha-1. The experiment was arranged in a split-plot design, with varieties as the main- plot factor and nitrogen rates as the sub-plot factor. The treatment combinations were replicated three times . Grain yield and yield parameters (thousand-kernel weight , grain number per head, number of heads per square meter and harvest index) were measured. Quality parameters were protein content percent and mixograph development time. Grin yield significantly (P<_0.05) increased with Application at Leribe averaging 3000 kg ha-1. Number of heads per square meter was also significantly(P<_0.05) increased while thousand kernel weight was significantly (P<_0.05) decreased at rates of N application higher than 40kg N ha-1. At Maseru and Mafeteng applied N had no effect on grain yield. Infact grain yield decreased with application of N over 20kg N ha-1 at Mafeteng. The number of heads per square meter also significantly(P<_0.05) decreased, suggesting poor emergence or tillering. At Maseru the thousand kernel weight was significantly (P<_0.05) decreased with increasing nitrogen application. Across the three sites grain yield increased significantly (P<_0.05) when N was applied over 20kg N ha-1. The number of heads per square meter also significantly (P<_0.05) decreased at higher rates of N application. Applied N fertilizer (P<_0.05) increased grain protein content. However, the protein contents of wheat at Maseru and Mafeteng were higher, averaging 11% and 15% respectively. This observation is probably due to a concentration effect of protein content due to small grain size.Mixograph development times were within the acceptable range of 2.5-4.0 minutes for wheat from all the three sites. The four varieties did not significantly differ in grain yield or quality at all the three locations. However, they significantly differed in mixograph development times with Tugela DN giving the highest value averaging 4.0 minutes, and the lowest being caledon at 2.5 minutes. This study has shown that wheat yields and quality in Lesotho can be improved by applying before recommendations of N fertilizer rates and management strategies under dry land conditions can be made to farmers in Lesotho.
Nitrogen Fertilizer influence on Wheat , Influence on Protein content of Wheat , Genotype and Nitrogen Fertilizer influence-crops