الفهرس 
INTRODUCTION
The objective of this studyOnly 14 pages are availabe for public view
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Abstract
A field experiment was carried out during 2016/ 2017 and 2017/ 2018 seasons at the Agronomy Department Experimental Farm, Agriculture Faculty, Assiut University to study the effect of foliar spray time by different zinc oxide nanoparticles sizes on production and quality of three bread wheat cultivars. The experiment was laid out in randomized complete block design (RCBD) using strip split plot arrangement with three replications. Zinc oxide as bulk (control) and nanoparticles sizes (30.6, 23.7 and 20.7 nm) were allocated horizontally, while, bread wheat cultivars (Sids-1, Sids-12 and Gemmeaza-11) were arranged vertically and zinc application time (30, 45 and 60 days after planting) were arranged in sub plots. Each sub plot area was 10.5 m2. Wheat grains were hand sown on 1st and 3rd December in the first and second seasons, respectively. Wheat plants were sprayed by the certain size of ZnO at the mentioned stages. The ZnO concentration was 300 ppm. The preceding summer crop was maize in both seasons. All other cultural practices recommended for wheat crop were done in both seasons. The obtained results can be summarized as follows:
1-Yield attributes traits:
1-a- Total chlorophyll (mg/m2)
Data reveal that the tested zinc oxide nanoparticles (ZnO NPs) sizes andbread wheat cultivars had a significanteffect on total chlorophyll trait (mg/m3) in both seasons.Also, the exhibited data show that the tested zinc foliar spray time had a highly significant effect on total chlorophyll trait in the first season, only.Here too, the second order interaction had a highly significant (P≤ 0.01) effect on total chlorophyll content in the two growing seasons. The highest mean value of total chlorophyll content in the first season (463.85 mg/m2) was registered from Sids-12 cultivar which was sprayed by minimum size (20.7 nm) of ZnO NPs at 60 days after planting. While, the highest mean value of total chlorophyll content in the second season (492.42 mg/m2) was registered from Gemmeza-11cultivar which was sprayed by minimum size (20.7 nm) of ZnO NPs at 45 days after planting.
1-b-Plant height (cm)
The obtained data reveal that the tested zinc nanoparticles sizes and bred wheat cultivars had a significant effect on plant height in both seasons. While, the effect of zinc application time on plant height not significant in both seasons. Here too, the second order interaction had a highly significant (P≤ 0.01) effect on plant height in the two growing seasons. The highest mean value of plant height in the first season (116.47 cm) was registered from Sids-1 cultivar which was sprayed by minimum size (20.7 nm) of ZnO NPs at 60 days after planting. While, the highest mean value of plant height in the second season (105.13 cm) was registered from Sids-1 cultivar which was sprayed by minimum size (20.7 nm) of ZnO NPs at 30 days after planting.
1-c-Spike length (cm)
The obtained results show that the second order interaction had a highly significant effect on spike length in both seasons. The highest mean value of spike length (16. 70 cm in the first season) was obtained from Gemmeza-11cultivar which was sprayed by minimum size (20.7 nm) of ZnO NPs at 45 days after planting. While, the corresponding value in the second season (14.87 cm) was obtained from Gemmeza-11cultivar which was sprayed by ZnO NPs size of 23.7 nm at 45 days after planting.
1-d-Number of spikelets spike -1
The obtained results show thatthe second order interaction had a highly significanteffect on number of spikelets spike-1 in the two growing seasons. The highest mean values of on number of spikelets spike-1 (24.80 and 21.65 spikelets spike-1 in the first and second seasons, respectively) was registered from Gemmeza-11cultivar which was sprayed by ZnO NPs of 30.6 size at 45 days after planting.
1-e- Number of spikes m-2
The presented results reveal that the second order interaction had a highly significant effect on number of spikes m-2 in the two growing seasons. The highest mean values of spikes number m-2 (562.67 and 564.00 spike m-2 in the two respective seasons) were obtained from sids-1 bread wheat cultivar which was sprayed by ZnO NPs (23.7 nm) at 30 days after planting in the first season, while the highest mean value in the second season was registered from sids-1 cultivar which was sprayed by ZnO NPs (20.7 nm) at 60 days after planting.
1-f-Number of kernels spike-1
The obtained results show that the second order interaction had a highly significant and significant effect on number of kernels spike in the first and second seasons, respectively. Sids-1 cultivar which was sprayed by minimum size (20.7 nm) of ZnO NPs at 45 days after planting produced the maximum mean value of kernels number spike-1 (78.20) in the first season. While, Sids-12 cultivar which was sprayed by minimum size (20.7 nm) of ZnO NPs at 30 days after planting produced the maximum mean value of kernels number spike-1 (81.40) in the second season.
1-g- Thousand kernel weight(g)
The obtained results prove that the second order interaction had a highly significant influence on 1000 kernel weight trait in both season. The highest mean value of 1000 kernel weight (50.62 g) in the first season was obtained from Gemmeza-11 bread wheat cultivar which was sprayed by minimum size of ZnO NPs (20.7 nm) at 30 days after planting. The corresponding mean value (56.95 g) in the second season was obtained from Sids-12 bread wheat cultivar which was sprayed by minimum size of ZnO NPs (20.7 nm) at 30 days after planting.
1-h-Weight of kernels spike-1
The obtained results show that the second order interaction had a highly significant (P≤0.01) and significant (P≤0.05) effect on kernels weight spike-1 in the first and second seasons, respectively. The highest mean value of kernel weight spike-1 (3.20 g) in the first season was obtained from Gemmeza-11 bread wheat cultivar which was sprayed by minimum size of ZnO NPs (20.7 nm) at 30 days after planting while, the corresponding value (3.90 g) in the second season was obtained from Gemmeza-11 bread wheat cultivar which was sprayed by ZnO NPs (23.7 nm) at 45 days after planting.
IV. 2- Yield traits
2-a- Biological yield (ton feddan-1)
It evident from the data that the tested zinc nanoparticles sizes, bred wheat cultivars, zinc application time treatments and their interactions involved in this respect had a significant effect on biological yield trait in both seasons. Sowing Sids-1 cultivar and sprayed it by minimum size of ZnO NPs (20.7 nm) at 60 days after sowing produced the highest mean values of biological yield feddan-1 (9.61 tons feddan-1) in the first season. Otherwise, sowing Sids-1 cultivar and sprayed it by minimum size of ZnO NPs (20.7 nm) at 45 days after sowing produced the highest mean values of biological yield feddan-1 (10.50 tons feddan-1) in the second season.
2- b- Grain yield (Ardab feddan-1)
The illustrated data show that the second order interaction had a significant effect on grain yield feddan-1in both seasons. The highest mean values of grain yield feddan-1(28.67 and 28.50 ardab feddan-1 in the first and second seasons, respectively) were obtained from planting Gemmeza-11 bread wheat cultivar which was sprayed by minimum size (20.7 nm) of ZnO NPs after 60 days from planting.
IV. 2-c- Straw yield (ton feddan-1)
The obtained results show that the second order interaction had a highly significant and significant effect on straw yield in the two respective seasons. Sowing gemmeza-11wheat cultivar and sprayed it by 30.6 nm ZnO NPs at 30 days after sowing gained the maximum mean value of straw yield (6.16 tons feddan-1) in the first season. Otherwise, sowing Sids-1wheat cultivar and sprayed it by 20.7 nm ZnO NPs at 45 days after sowing gained the maximum mean value of straw yield (6.70 tons feddan-1) in the second season.
3- Quality traits
3-a-Test weight (kg/hectoliter)
The exhibited data show that the second order interaction had a highly significant (P≤0.01) and significant (P≤0.05) effect on test weight trait in the first and second seasons, respectively. Sowing Sids-1 cultivar and sprayed it by 23.7 nm ZnO NPs at 30 days after planting produced the highest mean value of test weight (77.5 kg/ hectoliter) in the first season. On the other hand, sowing Gemmeza-11 cultivar and sprayed it by20.7 nmZnO NPs at 60 days after planting produced the highest mean value of test weight (80.87 kg/ hectoliter) in the second season.
3-b-Flour percentage (%)
The obtained results show that the second order interaction had a significant influence on flour percentage in the second season only. The highest mean value of flour percentage (83.50 %) in the second season was obtained from Gemmeza-11 cultivar which was sprayed by 23.7 nm zinc nanoparticles size at 30 days after planting.
3-c-Coarse branpercentage (%)
The obtained data focus that the second order interaction had a significant (P≤ 0.05) and highly significant (P≤ 0.01) effect on coarse bran percentage in the first and second seasons, respectively. Sowing sids-12 cultivar and sprayed it by zinc nanoparticles sizes of 23.7 and 30.6 nm at 45 days after sowing gained the lowest mean values of coarse bran percentage which were 12.63 and 11.00 in the first and second seasons, respectively.
3-d-Fine bran percentage (%)
The obtained data, the second order interaction had a significant (P≤ 0.05) and highly significant (P≤ 0.01) effect on fine bran percentage in the first and second seasons, respectively. In the first season, the lowest mean value of fine bran percentage (1.14 %) was registered when Sids-1 cultivar was sprayed by minimum size (20.7 nm) of ZnO NPs at 30 days after planting. While, the lowest mean value in the second season (1.50 %) was recorded when Sids-12 cultivar was sprayed by bulk zinc oxide (control) at 30 days after planting.
3-e-Wet gluten percentage (%)
The obtained data reveal that the second order interaction had a highly significant effect on grains wet gluten content in the two growing seasons.Sowing Sids-12 cultivar and sprayed it by minimum ZnO NPs size (20.7 nm) at 30 days after planting produced the highest mean value of grains wet gluten content (34.30 %) in the first seasons. While, the highest mean value of grains wet gluten content (30.90 %) in the second seasons was achieved from planting Sids-1 cultivar and sprayed it by minimum ZnO NPs size (20.7 nm) at 60 days after planting.
3-f-Dry gluten percentage (%)
The obtained results show that the second order interaction had a highly significant effect on grains dry gluten content in the two growing seasons. Sowing Sids-12 cultivar and sprayed it by minimum ZnO NPs size (20.7 nm) at 30 days after planting produced the highest mean value of grains dry gluten content (13.72 %) in the first seasons. While, the highest mean value of grains dry gluten content (14.37 %) in the second seasons was achieved from planting Sids-1 cultivar and sprayed it by minimum ZnO NPs size (20.7 nm) at 60 days after planting.
3-g- Fermentation time (minutes)
The illustrated data reveal that the second order interaction had a highly significant influence on fermentation time in the two growing seasons. Thus, planting Sids-12 cultivar and sprayed it by minimum ZnO NPs size (20.7 nm) at 30 days after planting produced the maximum mean value of fermentation time (54.88 minute) in the first seasons. while, the maximum mean value of fermentation time (57.48 minute) in the second seasons was achieved from planting Sids-1 cultivar and sprayed it by minimum ZnO NPs size (20.7 nm) at 60 days after planting.