Effects of zinc fertilizer application on yield and some quality characteristics of cowpea (Vigna unguiculata L.) under different irrigation conditions

Objective: In this study, the effects of zinc fertilizer application on grain yield and some quality characteristics of different varieties were determined in different irrigation applications of cowpea. Materials and Methods: The effects of zinc (3 kg / d) and non-zinc fertilization under full irrigation (100 %) and restricted irrigation (50 %) on the grain yield, some yield characteristics, the grain protein content and the grain amino acid content of Akkız, Karagöz and quindigenous cowpea variety were investigated. Results: According to the results, the difference between the varieties was significant in terms of the number of days of flowering, the height of the first pod, the weight of 100 grains and the grain yield. The interaction of irrigation * zinc * variety was found to be important in terms of physiological ripening time, plant height, number of plant branches, biological yield, and grain protein content. In terms of grain yield, Karagöz (381.86 kg/da) achieved the highest value among the varieties, followed by Akkız (354.98 kg/da). In terms of amino acid levels, the irrigation * cultivar interactions for methionine levels, irrigation * zinc in valine and zinc * cultivar interactions for aspartic acid were statistically significant and the difference between cultivars in arginine levels was important. The difference in phenylalanine levels between zinc applications was significant. Conclusion: It was observed that grain yield and protein content, as well as some amino acid levels, decreased under restricted irrigation conditions. It has been found that the addition of zinc fertilizer increases the zinc content of the grains. Among the varieties, the Karagöz variety became prominent in terms of grain yield and protein content. Key words: Cowpea, Vigna unguiculata L., Grain yield, Protein content, Amino acid