The Effect Of Exogenous Nitrogen On Wine Grape Physiology And Wine Quality

With the rapid development of Ningxia wine industry,there were many problems arising in the process of wine making,such as unreasonable fertilization,disharmony of nitrogen,phosphorus and potash fertilizer,the lack of nitrogen and the termination of fermentation.Taking the 8-year-old "cabernet sauvignon" as the experimental material,by studying the types and concentration of nitrogen,exploring the effects of different nitrogen application methods on soil environment,wine grape comprehensive characteristics,wine quality and yeast on assimilable nitrogen content,I focus on establishing a rational and further providing a scientific basis on producing high quality and efficient cultivation of wine grapes.The main research results are as follows:(1)Spraying different nitrogen on the leaf could improve wine grape fruit yield,ear length,intercellular CO2 concentration,stomatal conductance,net photosynthetic rate,chlorophyll a and total phenol content in wine samples,chromaticity,yeast assimilable nitrogen before fermentation and after,and consumption,which significantly reduced volatile acid content and tonality in wine samples.Spraying phenylalanine on grape veraison had the best effects on grape morphology,photosynthesis and wine quality,and could significantly increase the relative contents of two essential amino acids and two sesquiterpenes.The second was urea,which could significantly improve the content and consumption of yeast assimilable nitrogen in fruits,and also could improve the wine color with bright red.Glutamate could significantly increase the relative contents of three essential amino acids,sesquiterpenes and 20 triterpenes.Ammonium sulfate and calcium ammonium nitrate also promoted the improvement of wine grape quality.The former could improve the soluble solids and promote the accumulation of phenolic substances in fruits,while the later could significantly increase the content of yeast assimilable nitrogen and the fermentation amount of yeast assimilable nitrogen in grape juice.Spraying phenylalanine could effectively improve the growth and development of wine grapes and the quality of fruit and wine.(2)In the veraison of grape,spraying nitrogen with different concentration had different effects.When nitrogen concentration was 2.5‰,the most obvious result was that the content of wine grape physiological indicators and yeast assimilable nitrogen increased a lot,and hundred-grain weight,net photosynthetic rate,fruit soluble solids,titratable acid,total phenol content and yeast assimilable nitrogen in grape juice significantly improved.At the same time,the tannin,anthocyanin and fermentation amount of yeast assimilable nitrogen were significantly increased,while the ratio of sugar to acid in fruits and the total acid content in wine samples were decreased.When the nitrogen concentration reached 1.5‰,SOD began to decrease,and the accumulation rate of malondialdehyde content decreased.When nitrogen concentration reached 2.5‰,CAT activity began to decrease.When nitrogen concentration reached 3‰,POD activity began to decrease.Spraying urea with a concentration of 2.5‰ on the leaf surface during the verasion could effectively improve the growth of grape,the quality of fruit and wine.(3)Adopting different methods of nitrogen application in the verasion,the combination of spray and drop had the best effect,which mainly improved soil nutrient content,particle size of wine grape fruit,spike length,hundred-grain weight and yield are also significantly increased.At the same time,the improvement of leaf stomatal conductance,net photosynthetic rate,transpiration rate and carotenoids,fruit soluble solids,tannins was in the highest,as well as the quality of the wine.The combination fertilizer of spray and drop by half in the soil nutrient increased,leaf area,water use-efficiency,and the chlorophyll content also increased significantly.Soluble solids in fruit,dry extract in wine samples,tannins,anthocyanins and the total phenol and chroma were obviously highest,while the total acid,volatile acid and tonality were lowest.And the consumption of yeast assimilable nitrogen before and after fermentation significantly increased.Therefore,drip and spray fertilization had the best effect on soil nutrients,grape growth index,wine quality and wine sample.