Variation of Some Agro-Physiological and Biochemical Parameters of Wheat (Triticum aestivum L.) Varieties in Response to Nitrogen Fertilizer Rates at Djirataoua in Southern Niger Republic

Nitrogen is the most limiting plant nutrient element of soils in Niger. Farmers apply nitrogen to increase yield of cereal crops. A survey conducted at Djirataoua in southern Niger, revealed that wheat growers applied nitrogen fertilizer with less technical knowledge resulting in low response on growth and yield. To produce suitable recommendations to farmers, a field experiment was conducted during two dry seasons (2016/2017 and 2017/2018) at Djirataoua (13°25’59’’N, 7°8’12’’E). The aim of the study was to determine the optimum level of Nitrogen for highest yield and agro-physiological parameters of wheat varieties. Four Nitrogen levels (0, 100, 150 and 200 kg N ha-1) and four wheat varieties were evaluated in this study. The experiment was laid out in a split plot design with three replications. Data collected on grain yield, chlorophyll, Nitrogen uptake and protein content were subjected to the analysis of variance and mean comparison. The results showed that application of 150 kg N ha-1 Nitrogen resulted in highest grain yield (3202 kg ha-1), chlorophyll content (50.9 SPAD) N uptake (72.63 kg ha-1), and protein content (135.5 g kg-1). The wheat varieties were significantly different in these parameters. Reyna-28 and Sokoll/3/ produced higher grain yield and Nitrogen uptake. Higher protein content was observed in Norman and Sokoll/3/. Significant interactions were observed between Nitrogen rates and variety on yield characters, Nitrogen uptake and protein content. The highest grain yield, Nitrogen uptake and chlorophyll content were achieved by interaction of Reyna-28 and Sokoll/3/ with 150 kg N ha-1. Therefore, application of 150 kg N ha-1 and using varieties Reyna-28 or Sokoll/3/ is recommended to farmers for maximum grain yield and high protein content.