الفهرس 
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Abstract
Two field experiments were conducted at a private field in Derwatine Village, Nabarouh Center, Dakahlia Governorate, Egypt, during 2017/2018 and 2018/2019 seasons to study the effect of zinc foliar application treatments (chelated and nano forms), nitrogen fertilizer levels on yield and its attributes and grains quality of bread wheat Gemmiza 12 cultivar. The experiments were carried out in a strip-plot design with three replicates. The vertical-plots were assigned to five zinc foliar application treatments as follows: 1- Without foliar application (control treatment). 2- Foliar application with solution of chelated zinc in the form of Zn-EDTA and at the rate of 2 g/liter water in each spraying. 3- Foliar application with solution of nano zinc at the rate of 200 mg/L in each spraying. 4- Foliar application with solution of nano zinc at the rate of 400 mg/L in each spraying. 5- Foliar application with solution of nano zinc at the rate of 600 mg/L in each spraying. Aqueous solutions of zinc sulfate and ascorbic acid were prepared using deionized water with three concertation levels (200, 400 and 600 ppm) for both solutions. Each concentration of ascorbic acid (20 mL) was added to the same concentration of metal salt solution (20 mL) by dropping very carefully to avoid rapid reaction which causes larger particle size and formation of precipitate under stirring for 2 hours at room temperature. The resulting nanoparticles were synthesized in an equimolar ratio of (1:1). The horizontal-plots were allocated to three nitrogen fertilizer levels as follows: 1- 100 % of the recommended dose (80 kg N/fed). 2- 80 % of the recommended dose (64 kg N/fed). 3- 60 % of the recommended dose (48 kg N/fed). Studied characters: A-Nanoparticles characteristic. B- Yield and its attributes: 1- Plant height (cm). 2- Number of spikes/m2. 3- Spike length (cm). 4- Number of spikelets/spike. 5- Number of grains/spike. 6- Grains weight/spike (g). 7- 1000 – grain weight (g). 8- Grain yield (ardab/fed). 9- Straw yield (t/fed). C- Grains quality: 10- Crude protein percentage in grains (%). 11- Total carbohydrates percentages in grains (%). • The most important results obtained from this investigation can be summarized as follows: 1. Effect of zinc foliar application treatments: Regarding the effect of zinc foliar application treatments (foliar application with solution of chelated zinc in the form of Zn-EDTA and at the rate of 2 g/liter and foliar application with solution of nano zinc at the rates of 200, 400 and 600 mg/L in each spraying in addition control treatment i.e. without zinc foliar application) on yield and its attributes (plant height, number of spikes/m2, spike length, number of spikelets/spike, number of grains/spike, grains weight/spike, 1000 – grain weight, grain and straw yields/fed) and grains quality characters (crude protein and total carbohydrates percentages in grains), it was significant in the two growing seasons. It is clearly seen that, foliar spraying wheat plant twice (after 35 and 50 days from sowing) with solution of nano zinc at the rate of 400 mg/L in each spraying was the best transaction to increase yield and its attributes and grains quality characters, which recorded the highest values of all these character in the two growing seasons. Foliar spraying wheat plants twice also with solution of nano zinc at the rate of 600 mg/L in each spraying ranked secondly after the intermediate rate of nano zinc (400 mg/L) concerning its effect on yield and its attributes and grains quality characters, followed by foliar spraying two times also with solution of nano zinc at the rate of 200 mg/L in each spraying and then foliar spraying two times also with solution of chelated zinc in the form of Zn-EDTA and at the rate of 2 g/liter water in each spraying in the first and second seasons. On the contrary, control treatment (without zinc foliar application) gave the lowest values of yield and its attributes and grains quality characters in both seasons. 2. Effect of nitrogen fertilizer levels: With reference to the effect of nitrogen fertilizer levels i.e. 100, 80 and 60 % of the recommended dose (80, 64 and 48 kg N/fed) on yield and its attributes (plant height, number of spikes/m2, spike length, number of spikelets/spike, number of grains/spike, grains weight/spike, 1000 – grain weight, grain and straw yields/fed) and grains quality characters (crude protein and total carbohydrates percentages in grains), it is apparent from obtained results indicated that each increase in nitrogen fertilizer levels was accompanied with significant increase in all studied characters. Mineral fertilizing wheat plants with the highest level of nitrogen fertilizer levels (100 % of the recommended dose i.e. 80 kg N/fed) gave the highest values of yield and its attributes and grains quality characters in the first and second seasons. However, mineral fertilizing wheat plants with 80 % of the recommended dose i.e. 64.0 kg N/fed ranked secondly after the highest level of nitrogen fertilizer levels regarding its effect on yield and its attributes and grains quality characters in the first and second seasons. Whereas, mineral fertilizing wheat plants with 60 % of the recommended dose i.e. 48.0 kg N/fed produced the lowest values of all yield and its attributes and grains quality characters in the first and second seasons. 3. Effect of interaction: The obtained results of this study indicated that there was a significant effect due to the interaction between both studied factors (zinc foliar application treatments and nitrogen fertilizer levels) on plant height (in the first season), spike length (in the second season), number of spikes/m2, number of spikelets/spike, number of grains/spike, grains weight/spike, 1000 – grain weight, grain and straw yields/fed, crude protein and total carbohydrates percentages in grains (in both seasons). from the achieved results of this study, it could be noticed that mineral fertilizing wheat plants with 100 % of the recommended dose i.e. 80 kg N/fed in addition foliar spraying two times (after 35 and 50 days from sowing) with solution of nano zinc at the intermediate rate (400 mg/L) in each spraying resulted in highest values of all studied yield and its attributes and grains quality characters the first and second seasons. However, the second best interaction treatment was mineral fertilizing wheat plants with 80 % of the recommended dose (64.0 kg N/fed) besides foliar spraying also with solution of nano zinc at the rate of 400 mg/L in each spraying and followed by mineral fertilizing wheat plants with 100 % of the recommended dose i.e. 80 kg N/fed and foliar spraying with solution of nano zinc at the rate of 600 mg/L in each spraying in both seasons. Conclusion from the accomplished results of this study, it could be concluded that foliar spraying wheat Gemmiza 12 cultivar twice after 35 and 50 days from sowing with solution of nano zinc at the rate of 400 mg/L in each spraying besides mineral fertilizing with 80 kg N/fed to produce maximum productivity and quality. While, to maintain high productivity and grains quality at the same time reduce production costs and environmental pollution, it could be recommended that foliar spraying twice with solution of nano zinc at the rate of 400 mg/L in each spraying besides mineral fertilizing with 64 kg N/fed under the environmental conditions of Nabarouh Center, Dakahlia Governorate, Egypt.