RESPONSE OF THEE WHEAT VARIETIES TO NITROGEN LEVELS, SEEDING RATES AND THEIR COMBINATION: 3- STRAW YIELD AND ITS COMPONENTS

The aim of this investigation was to estimation the effect of three nitrogen levels, i.e. 60, 80 and 100 kg N/fed (one feddan=4200m2), three seeding rates, i.e. 40, 60 and 80 kg grain/fed and three wheat varieties, i.e. Giza-171, Gemmiza-12 and Shandawel-1 under the conditions of Agricultural and Experiments Research Station at Giza, Faculty of Agriculture, Cairo University, Egypt through 2018/2019 and 2019/2020 wheat growing 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 m2. The most important results obtained were as follows: nitrogen fertilizer levels had significant effect on time of 50% heading, plant height, and number of tillers/m2, biological yield and straw yield in both seasons. The highest values for the previous mentioned traits were obtained at either 100 or 80 kg N/fed. Seeding rates had also significant effect on the most of studied traits which gave the highest values at either 60 or 80 kg grains/fed in both seasons. Moreover, all studied traits significantly affected among verities in both seasons where Giza-171 and Gemmiza-12 verities surpassed Shandawel-1 variety in the most of studied traits. The most of studied interactions significantly affected one or more of studied traits in both seasons. The optimum treatment for producing the maximum straw yield was either Giza-171 or Gemmiza-12+either 80 or 60 kg grains/fed +100kg N/fed in both seasons, respectively.