Effects Of Water,Nitrogen And Phosphorus Coupling On Growth And Nutrient Uptake And Utilization Of Stem Fruiting Pear

In this experiment,the Korla fragrant pear grafted for 5 years was taken as the research object,combined with the water and fertilizer integration technology,and the three-factor two-level randomized block test design was used to carry out the field plot test.The amount of pure nitrogen in the annual growth cycle was 300 kg·hm^-2（N1）,375 kg·hm^-2（N2）,the amount of P₂O₅in the annual growth cycle was 225kg·hm^-2（P1）,300 kg·hm^-2（P2）,and the amount of irrigation in the annual growth cycle was 6300 m³·hm^-2（W1）,6720 m³·hm^-2（W2）.There were 8 treatments in total,and the amount of potassium fertilizer was the same among the treatments.Through different water nitrogen and phosphorus coupling treatments,the effects of different water nitrogen and phosphorus coupling treatments on the growth and development of fragrant pear trees,fruit quality and soil nutrient absorption and utilization were explored,and the growth and development rules of fragrant pear trees were mastered.The demand for fertilizer and irrigation amount of pear trees was discussed,and a reasonable water and fertilizer formula was matched to provide a scientific basis for the scientific planting of fragrant pears.（1）Different water nitrogen and phosphorus coupling treatments had different effects on the growth and development of each part of pear trees.In all water nitrogen and phosphorus coupling treatments,the growth rate of pear branches was fast and then slow,the length of branches ranged from 34.40 to 45.10 cm,and the diameter of branches increased by 2.80 to 3.14 mm.The length of branches in T3 treatment increased by 45.10 cm,and the diameter of branches increased by 3.14 mm,which was significantly higher than other treatments.The trend of leaf area index in the whole annual growth cycle was’rapid increase-slow increase-slow decrease’.The leaf area index of each treatment was different in each annual growth cycle,and the leaf area index was the highest in the early stage of fruit expansion.In the 0～60 cm soil layer,the root density,root surface area,root diameter and root volume of each treatment were different in different soil layers.（2）The response of plant nutrient content and soil nutrient changes to different water nitrogen and phosphorus coupling treatments was different.The contents of alkali-hydrolyzable nitrogen and available phosphorus in 0～60 cm soil decreased with the increase of soil depth.The variation range of alkali-hydrolyzable nitrogen in each soil layer was 20.27～37.10 g·kg^-1,16.70～32.77 g·kg^-1,12.13～29.40 g·kg^-1.The content of available phosphorus in each soil layer was 32.34～97.09 g·kg^-1,24.90～70.52 g·kg^-1and 19.25～43.05 g·kg^-1,respectively.Among them,T2 treatment was significantly higher than other treatments in the flowering period and young fruit development period.In the other annual growth cycle,T2 treatment was lower than T6 and T4 treatments,but there was no significant difference.Under the same soil layer,the content of alkali-hydrolyzable nitrogen and available phosphorus changed consistently with the annual growth cycle.The total nitrogen content of branches and leaves of T3 treatment was the highest at the flowering stage and the early stage of fruit enlargement.The total phosphorus content of leaves under each treatment had no regular change,and the total potassium content of leaves continued to decline throughout the annual growth cycle.The consumption of potassium in leaves of T3treatment was greater than that of other treatments.（3）During the growth and development of pear trees,the growth rate of fruit longitudinal diameter was always greater than that of fruit transverse diameter,and the increase of fruit longitudinal diameter was greater than that of fruit transverse diameter.Taking time as independent variable and fruit shape index as dependent variable,the least square method was used to fit the curve of fruit shape index under different measuring days.The results showed that R²was the largest under T3treatment,which was the closest to the growth law.At the same time,the total yield was the highest under T3 treatment,which was 4916.67 kg·hm^-2,and the first-class fruit rate was the highest,which was 78.14%.The contents of soluble sugar,soluble solids,vitamin C and phenols were high.The low content of titratable acid and stone cells is an ideal manifestation of good quality of fragrant pear.The fruit quality indexes under T3 treatment were significantly higher than those under other treatments.In summary,under T3 treatment(nitrogen application rate of 375 kg·hm^-2,phosphorus application rate of 225 kg·hm^-2,irrigation amount of 6300 m³·hm^-2),the growth and development of fruit trees were the best,and the quality of pear fruit was the best.