Effects Of Reduced Nitrogen On Tree Nutrition And Fruit Quality Of Table Grape ’Ruby Seedless’

Grape is an important economic crop in China.Because of excessive and mindless applying chemical fertilizers by domestic growers in main grape production areas,however,which had caused low nitrogen use efficiency and environmental pollution.In this study,10-year-old ‘Ruby seedless’ plants in the field were used as experimental materials to study how reduced nitrogen affect vine nutrition and fruit quality through applying fertilizers that contain different amount of nitrogen on grapevines in 2019 and 2020.Main results were described as follow:(1)Broadcast reduced-nitrogen fertilizers1.1 Common chemical fertilizer was used as control and mixing fertilizer with equal amount of nitrogen was the treatment,results showed that compared to the control,the treatment uptook significant more phosphorus in all growing stages of vines;dry weight of pruned branches and fruit,content of nitrogen,phosphorus and potassium,nitrogen and potassium uptake in the all growing stages of vines showed no significant difference.At the same growing stage and same parts of shoot,leaf SPAD values showed no significant difference when compared to the control.Compared to the control,no significant difference was shown in other fruit quality indexes,such as total soluble solids and total sugar,except for titrated acid.1.2 Mixed fertilizer with equal amount of nitrogen was treated as control and mixed fertilizer with 10%,20%,and 30% reduced nitrogen.Results showed that there were no significant differences in SPAD value of leaves,dry weight of pruned branches,nitrogen,phosphorus and potassium contents among all treatments compared with the control at the same time.Compared to the control,fruit dry weight and plant biological yield under 10% and 20% reduced nitrogen treatments were significantly decreased 16.6% and 20.8%,respectively,and 18.6% and 21.1%,respectively.Nitrogen uptake in all growing stages of vines with 10% reduced nitrogen was significantly lower than that of the control by 17.6%.The phosphorus content of fruit under 20% and 30% reduced nitrogen treatments was significantly lower than that of the control group by 30.2% and 23.2%,respectively,and the phosphorus content in all growing stages of vines for all treatments was significantly lower than that of the control.The potassium content in all growing stages of vines treated with 30% reduced nitrogen was significantly lower than that of control(19.0%).Compared to the control,fruit diameter,berry weight,and other fruit quality indexes of the treatment with 10% reduced nitrogen showed significant difference.(2)Reduced nitrogen test by the integration of water and fertilizer:2.1 Sprinkled regular chemical fertilizers irrigation control,sprinkled regular chemical fertilizer drop water treatment,equal nitrogen amount mixed fertilizer water and fertilizer integrated treatment test,results showed: In the same year(2019,2020),compared to the control,there were no significant differences in dry weight,nitrogen,phosphorus and potassium contents of pruned branches and fruits,nitrogen,phosphorus and potassium uptake at all growing stages of vines,SPAD value of leaves at the same position and fruit quality in the same period.In addition,there was no significant difference in the net photosynthetic rate of one leaf above the cluster in the same period between all treatments and the control in 2020.2.2 Integrated control with equal amount of nitrogen and mixed fertilizer,water and fertilizer,and integrated treatment with reduced nitrogen by 10%,20%,30%,40%and 50%.Results showed that compared to the control in 2019,the dry weight,nitrogen,phosphorus and potassium contents of pruned branches and fruits,and the absorption of nitrogen,phosphorus and potassium at all growing stages of vine were not significantly different.The SPAD values of three leaves above the cluster in the water and fertilizer integration treatments with 40% and 50% reduced nitrogen were significantly lower than those of the control at the stage of fruit expansion,and there was no significant difference in the SPAD values of the leaves in the same position at the same growing stage.No significant difference was observed in fruit quality between each treatment and the control.2.3 Applying nitrogen-free mixed fertilizer through the integration of water and fertilizer was treated as the control,equal amount of nitrogen,reduced nitrogen 10%,20%,30%,40% mixed fertilizer,water and fertilizer integration test,Results showed:There were no significant differences in fruit dry weight,nitrogen,phosphorus and potassium contents,nitrogen,phosphorus and potassium uptake at all growing stages of vine,SPAD value and net photosynthetic rate of one leaf above the cluster in 2020 when compared to the control.On April 30,the potassium content of pruned branches reduced by 30% of nitrogen was significantly higher than that of the control,but there were no significant differences in dry weight,nitrogen,phosphorus and potassium contents of pruned branches at the same period.There was no significant difference in fruit quality between the control and each treatment.In conclusion,types of chemical fertilizer application,nitrogen fertilizer application methods,and reduced nitrogen fertilizer showed no significant effects on vine nutrition and fruit quality,which can provide some reference for scientifically managing fertilization in grapevines.