ABSTRACT
To achieve larger production per unit area, sciences and farmers face a great defiance in improving cropping practices and elicitation new top yielding wheat varieties and also to establish the effects of these factors on the spike characters. Two years experiment were conducted to evaluate the effect of three nitrogen fertilizer levels (recommend rate 80 kg N/fed and 25% lower and higher than the recommended, i.e. 60 and 100 kg N/ fed, three seeding rates (40, 60 and 80 kg grains/fed) and there varieties (Giza-171, Gemmiza-12 and Shandawil-1), on spike characters of wheat at the Agricultural and experimental Research Station, Faculty of Agriculture, Cairo University, Giza, Egypt during 2018/2019 and 2019/2020 seasons. The experimental design was a split- split plot in randomized complete block arrangement with three replications. Nitrogen levels were allocated to the main plots, while the sub plots were assigned for seeding rates. Wheat varieties were distributed at random in the sub-sub plots. Each sub-sub plots area 4 m (2 x 2m). Generally, results indicated that significant effect on spike length and number of grains/ spike in both seasons and on weight of grains/ spike and 1000-grain weight in one season, where the tallest and heaviest spike as well as the heaviest 1000-grain weight were produced at the 100 kg N/fed in both seasons but the highest number of grains/spike was obtained at 80 kg N/fed in one season. It could be concluded that application nitrogen at the rate of 100 kg/fed proceed the favorable effect on spike characters under the environmental conditions of the experimental site and the similar conditions. Seeding rates caused a significant effect on all studied traits in one season, so the highest values were at 80 kg grains/fed, but this effect on 1000-grain weight was true in both seasons, where the highest value was at 60 kg grains/fed. Moreover, varieties were significantly differed in all spike character in both seasons except number and weight of grains/spike in one season where Giza-12 variety surpassed others. Al studied interactions had significant effect on all studied traits either in one or two season. Planting Giza-171 with 80 kg grains/fed and application of 100 kg N/fed was the pest treatment.