| In this paper,different application methods(soil application and spray application)and the dosage(base application 2.5,5,7.5 kg/hm~2,spraying 0.1%,0.3%,0.5%)of chelated zinc fertilizers(amino acid chelated zinc,EDTA chelated zinc,and fulvic acid chelated zinc)were conducted in 2017 and 2018 years to study the change of the grain yield,zinc content and quality of rice.The effect of zinc fertilizer application in the soil with different available zinc(rich zinc(DTPA-Zn 2.8mg/kg),low zinc(DTPA-Zn0.72mg/kg))was demonstrated(2019).At the same time,pot experiments were conducted to study the physiological functions of chelated zinc fertilizers(2019 and2020).The results were as follows:1.The field experiment showed that the number of tillers per plant,SPAD,photosynthesis and the grain yield of rice were increased by the application of 5.0kg/hm~2EDTA chelated zinc fertilizer or 5.0 kg/hm~2amino acid chelated zinc fertilizer in two years(2017 and 2018).Compared with CK,the grain yield was increased by7.5%and 7.3%.Compared with the treatment of zinc sulfate(the 5.0 kg/hm~2dosage),the grain yield was increased by 5.4%and 5.2%.The main reason for the improved grain yield is the increased effective panicles,1000-kernel weight and seed setting rate.at the same time,the dosage of 5.0 kg/hm~2of zinc EDTA chelated or the dosage of 5.0kg/hm~2of zinc-amino acid chelated plays a positive role in promoting zinc absorption and improving rice quality.Compared with the treatment of zinc sulfate(the 5.0 kg/hm~2dosage),the zinc content in milled rice was increased by 17.2%and 21.8%,the head rice rate of rice was increased by 8.6%and 6.6%,the protein content of rice was increased by 22.5%and 18.8%,respectively.2.The field experiment showed that SPAD and photosynthesis of rice leaves and the grain yield of rice were increased in the foliar application of 0.3%zinc-fulvic acid chelate or 0.3%zinc-amino acid chelate in two years(2017 and 2018).Compared with CK,the grain yield was increased by 4.9%and 4.7%,and compared with zinc sulfate(0.3%),the grain yield was increased by 4.9%and 4.7%1%and 2.0%,mainly due to the increase of 1000 grain weight and seed setting rate.At the same time,zinc content and quality of rice were promoted by spraying zinc chelate fertilizer.Compared with zinc sulfate(0.3%),the zinc content of milled rice,the head rice rate and the protein content were increased by 33.7%and 29.3%,7.8%and 6.7%,29.1%and 28.3%in the foliar application of 0.3%zinc-fulvic acid chelate or 0.3%zinc-amino acid chelate,respectively.3.The application demonstration of chelated zinc fertilizer was conducted in the paddy fields soil with different available zinc(2019).The results showed that the rice yield was not improved significantly after the application of zinc fertilizer in paddy fields with higher available zinc content.However,the grain yield was significantly increased by the application of 5.0 kg/hm~2amino acid chelated zinc fertilizer,in the foliar application of 0.3%zinc-fulvic acid chelate or 0.3%zinc-amino acid chelate in paddy field with lower available zinc content.Compared with CK,the grain yield was increased by 12.9%,10.4%and 10.2%.Compared with the treatment of zinc sulfate,the grain yield was increased by 3.4%,2.7%and 2.9%,respectively.At the same time,the zinc content in milled rice and brown rice was increased by 9.6%,14.4%,10.6%,and10.2%,25.4%,21.2%,the head rice rate was increased by 5.5%,5.1%and 4.1%,and the protein content was increased by 20.5%,22.1%and 19.8%,respectively,compared with the treatment of zinc sulfate.That is,basal application of chelated zinc fertilizers was more conducive to the improvement of rice yield than foliar application,and foliar application was better than basal application in improving grain zinc content.Therefore,amino acid chelated zinc with the dosage of 5.0 kg/hm~2could be selected when the grain yield was the main in paddy fields with low soil available zinc content.In order to increase the zinc content of grain,foliar spraying amino acid chelated zinc or fulvic acid chelated zinc with the dosage of 0.3%could be used.A positive effect on rice yield and quality was presented at amino acid chelate zinc by basal application or foliar spraying.4.The content of zinc(Zn)and iron(Fe)in grains were improved and the content of phosphorus and phytic acid were reduced at the treatments of basal application of amino acid chelated zinc with the dosage of 5.0 kg/hm~2,spraying amino acid chelated zinc or fulvic acid chelated zinc with the dosage of 0.3%in there years(2019 and 2020).The trend of Zn and Fe in grains at different position was showed as strong grains>medium grains>weak grains,and the trend of P and phytic acid was showed as strong grains<medium grains<weak grains.The molar ratio of phytic acid to zinc was reduced with the dosage of basal application of amino acid chelated zinc 5.0 kg/hm~2and spraying amino acid chelated zinc 0.3%.It was the best effect to increase the bioavailability of zinc.Compared with zinc sulfate,the molar ratio of the phytic acid and zinc in the strong,medium and weak milled rice were decreased by 45.0%,43.5%,33.9%and 53.5%,40.4%,14.4%,respectively.At the same time,the contents of chlorophyll a,b,a+b,soluble protein,soluble sugar,the activities of SOD,POD and CAT enzymes in the leaves of rice at tillering stage,filling stage and booting stage were increased with the dosage of 5.0 kg/hm~2amino acid chelated zinc,spraying 0.3%amino acid chelated zinc or 0.3%fulvic acid chelated zinc.Thereby,the photosynthesis,the grain yield and quality of rice were improved.Compared with CK and the treatment of zinc sulfate,the grain yield was increased by 21.0%,13.5%,10.1%,and 16.1%,8.2%,5.0%with the basal application of amino acid chelated zinc 5.0 kg/hm~2,spraying fulvic acid chelated zinc 0.3%or amino acid chelated zinc 0.3%treatment,respectively.And the trend of the head rice rate and the protein content of the rice panicle at different position was showed as strong grains<medium grains<weak grains. |
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