Research On Water And Fertilizer Integration Technology For Dwarf Apple Orchards In Longdong Area Of Gansu

The Longdong region of Gansu is located in the gully area of the Loess Plateau in eastern Gansu and is a high-quality apple production belt in China.Due to the natural conditions in the Longdong region,the water and fertiliser utilisation rate is low,which seriously affects the stable development of the apple industry in the Longdong region.It is a practical need to investigate the reasonable and scientific application rate and frequency of fertiliser to improve quality and efficiency.Based on this development,this experiment investigated the effects of different fertilizer application rates and times on apple leaf growth index,fruit quality and yield,and soil physical and chemical properties under the water-fertilizer integration system of the Gansu Qingcheng Apple Experiment Station of Northwest Agriculture and Forestry University of Science and Technology,with a view to screening out the appropriate fertilizer application rates and times for high-quality fruit production in Gansu Longdong region,and providing a theoretical basis for scientific fertilizer application in Gansu Longdong region.The main results of this experiment are as follows:1.In 2021,four different NPK fertilization patterns were set up in apple orchards according to different fertility periods CK(budding stage: 1:0.32:1.36,bud differentiation:1:0.63:2.73);S1(budding stage: 1:0.09:0.57,flowering stage: 1:0.5:0.97,bud differentiation:1:0.63:3.4,fruit expansion: 1:0.3:5.9);S2(budding: 1:0.17:0.65,anthesis: 1:0.35:0.97,phloem differentiation: 1:0.7:2.6,fruit expansion: 0:1:9.3);S3(budding: 1:0.2:0.47,anthesis:1:0.4:1.2,phloem differentiation: 1:0.4:2.9,fruit expansion: 0:1:9).(fruit expansion stage:0:1:7.78),irrigation volume was kept at the same level for all four fertilizer application patterns,and irrigation volume was 15 kg/plant/time for five times.Compared with CK,the different fertilizer application patterns increased leaf chlorophyll content,longitudinal and transverse fruit diameter,fruit weight per fruit,yield and fruit commercial rate,with S3 having the highest yield,increasing by 16% compared with CK.Compared with CK,the L*values(fruit brightness)of fruit colour tended to decrease,fruit a* values(degree of fruit colour)increased and b* values(fruit base colour)decreased in S1,S2 and S3 patterns,but There was no significant difference in the colour ratio(a/b*)of the fruit;the different fertiliser treatments increased the fruit hardness,soluble solids and solid acid ratio compared to CK,among which,the S2 treatment increased the fruit hardness by 4.3%,decreased the titratable acid content by 4.7% and increased the solid acid ratio by 4.9% compared to CK.The fruit quality under the S2 fertilization model was the best.2.In 2022,three different fertilizer treatments(CK: 6 fertilizer applications/year;T1: 12 fertilizer applications/year;T2: 18 fertilizer applications/year)were set up in apple orchards at different fertility periods,showing that different fertilizer applications improved tree growth,increased leaf SPAD,promoted new shoot growth,increased longitudinal and transverse diameter,fruit weight per unit,yield,fruit merchantability,and It also reduced the titratable acid content and increased the solid to acid ratio and fruit functional matter.Overall,the best fruit quality was achieved with the T2 treatment.3.The results of the two-year experiment concluded that the different fertilization rates increased the total N,P and K contents of leaves and fruits compared to CK,and that the effects of different fertilization rates on the mineral element contents of leaves,fruits and soil showed the same pattern of changes.The correlation between leaf SPAD values and mineral element contents of leaves and fruits showed that there was a complex correlation between leaf SPAD values and mineral element contents of leaves and fruits,as well as between mineral element contents of leaves and fruits,and that different fertilization treatments affected the antagonistic synergistic effects between soil mineral elements,thus affecting the distribution of mineral nutrients in the tree.4.Combined with the results of the experiment,it is recommended to use the S2 fertilizer application ratio pattern(budding stage: 1:0.17:0.65,flowering stage: 1:0.35:0.97,bud differentiation stage: 1:0.7:2.6,fruit expansion stage: 0:1:9.3,fruit ripening stage:1:0.98:0.78)combined with irrigation 18 times in Gansu Longdong region under the integrated water and fertilizer model programme.