| Zinc is one of the essential trace elements for the growth of wheat.The effects of zinc deficiency on wheat yield and quality were investigated.The study on the effect of zinc fertilizer on wheat quality can of a great significance to improve wheat quality.This study used Yangmai 16 as experimental materials,and the effects of spraying zinc fertilizer at different wheat growth periods on grain quality and spatial distribution would provide theoretical basis for a sensible application of Zn fertilizer and wheat quality optimization.The main results of the study are as follows:1 Effects of foliar Zn application on grain nitrogen and zinc contents and nitrogen metabolism enzyme activity during grain filling stagesCompared with CK,foliar Zn application significantly increased the content of Zn in wheat grain during grain filling and maturity stages as well as it promoted the accumulation of nitrogenous substances in wheat grain.Spraying zinc increased the accumulation of zinc in different organs of wheat plants that was higher at 15 DAA than that at other periods.Foliar zinc fertilizer improved the nitrogen accumulation in different organs of wheat.Foliar zinc application increased the activities of nitrate reductase(NR),glutamine syntheses(GS)and alanine aminotransferase(GPT)during grain filling stages of wheat.The effects of spraying zinc fertilizer at 5DAA on nitrogen accumulation and nitrogen metabolism enzyme activity were better than the other periods.2 Effects of spraying zinc fertilizer on grain quality of wheatCompared with the control,the application of foliar zinc fertilizer increased the zinc content in wheat flour and promoted the accumulation of nitrogen content significantly.Spraying zinc fertilizer increased the content of total protein,protein components including glutenin polymer(GMP),high molecular weight glutenin subunits and low molecular weight glutenin subunits(HMW-GS/LMW-GS).Foliar application of zinc fertilizer also significantly increased the dry and wet gluten content and gluten index,while the volume of bread increased,hardness and chewiness decreased significantly,the baking quality also improved.Baking quality and wet gluten content at 5 DAA were higher than that at jointing stages and at 15 DAA and 25 DAA,but changes in dry gluten content and gluten index were not significant under different treatments.Zinc has potential to combine with nitrogen compounds in the grains,which may be the main reason for the effects of zinc on increasing the nutritional and processing quality of wheat grains.3 Effects of foliar zinc fertilizer on spatial distribution of grain quality in wheatZinc content in the outer layer of wheat grain was maximum,and then decreased gradually inwards;whereas zinc in the endosperm was minimum.The contents of protein and its components in wheat grains increased from the outside to the inside and then decreased.Total protein,albumin,globulin and glutenin macropolymer(GMP)contents were maximum in wheat aleurone layer and they were minimum in the internal endosperm.Gliadin,glutenin and HMW/LMW-GS were highest in wheat subaleurone layer;while the internal layer of the endosperm had lowest.Compared with the control,spraying Zn significantly increased the zinc content in wheat grain in all layers whereas,increased the protein and its components contents in P2,P6,and P7 layer.From the results of the study,it was concluded that foliar zinc fertilizer application at different growth stages increased the grain quality and spatial distribution including the physiological mechanisms in wheat.the effects of zinc application on wheat grain quality were more significant in the internal endosperm.The effect of zinc spraying at different levels on the zinc ’content of wheat grain was maximum at 15 DAA.At 5DAA,the effect of zinc fertilizer on wheat grain quality was most excellent. |
