Effect Of Coupling Of Water And Fertilizer And Physiological Response Of Apple Tree

Taking8to11years old Fuji apple as experimental material, taking flood irrigationaround the tree base as control, a field experiment was conducted to research the effect ofwater storage subsurface irrigation fertilization on tree growth, fruit yield and quality, contentand spatial distribution of soil water and soil N, root physiological characteristics, canopylight environment and photosynthetic characteristics of leaves; The effect of different waterand N supply level on new shoots and leaves growth, fruit yield and quality; The effect oforchard mulching treatments on water conservation, soil nutrients, soil enzyme activity andmicrobial characteristics under water storage subsurface irrigation fertilization. The mainresults were as follows:1Compared with flood irrigation around the tree base, subsurface irrigation treatmentsslowed lengthening growth of new shoots, and had no significant effect on the thickeninggrowth of new shoots; Reduced leaf area, increased specific leaf weight;Substantially increased the number of root diameter less than2mm and distribution ratio in20~40cm soil layer, and also increased root surface area, total root length and number of roottips; Yield and fruit weight decreased, but key quality indicators such as color index, fleshfirmness and soluble solids content had improved. Compared with flood irrigation, fruit yieldand fruit weight of subsurface irrigation treatment buried4storage and infiltration pots had noobvious decline, but flesh firmness and soluble solids content of subsurface irrigationtreatment buried4storage and infiltration pots had significant or extremelysignificant increase. By analyzing the effect of subsurface irrigation treatments on tree growth,fruit yield and quality, we concluded that under the experimental orchard conditions,subsurface irrigation treatment buried4storage and infiltration pots was a more appropriatewater and fertilizer management measure.2Seasonal variation of soil water content under subsurface irrigation and flood irrigationaround the tree base had the same trend, and both were mainly affected by naturalprecipitation and its seasonal distribution. At different growth period of fruit trees, soil watercontent of subsurface irrigation treatments increased with the increase of the number ofstorage and infiltration pot, and soil water content of subsurface irrigation treatment buried3or4storage and infiltration pots was higher than that of flood irrigation around the tree base; Compared with flood irrigation around the tree base, subsurface irrigation treatmentssubstantially reduced the amount of water transporting to the deep soil.3Compared with flood irrigation around the tree base, subsurface irrigation treatmentssignificantly reduced the content of total N, hydrolyzable N and NO3--N in deep soil, andmade them mainly distributed in the concentrated distribution area of roots. With the increaseof soil depth, the content of total N, hydrolyzable N, NO3--N and NH4+-N of subsurfaceirrigation and flood irrigation around the tree base showed a trend of first increase and thendecrease, and all were the highest in20~30cm soil layer.4Compared with flood irrigation around the tree base, content of IAA of subsurfaceirrigation treatments increased in different level at different growth period of fruit trees, butcontent of ZR and GA3decreased in different level; Content of ABA of subsurface irrigationtreatment buried1or2storage and infiltration pots had significant or extremelysignificant increase, and content of soluble sugar, proline and MDA, and activity of SOD,POD and CAT also increased in different level.5Compared with flood irrigation around the tree base, subsurface irrigation treatmentsimproved canopy light conditions, decreased LAI, and increased coefficient for diffuseradiation transmission and coefficient for solar radiation transmission; Pn, CE and Tr ofsubsurface irrigation treatments decreased in different level, but CI increased; Variation ofWUE of subsurface irrigation treatments was complex, affected by the number of storage andinfiltration pots.6With the increase of water and N supply level, length of new shoots, leaf area, yieldand fruit weight showed a trend of gradual increase; Under the same water supply level,length of new shoots, leaf area, yield and fruit weight all increased with the increase of Nsupply level, and the higher level of water supply, the more obvious effect of increasinglength of new shoots, leaf area and yield. Under the same N supply level, soluble solidscontent showed a trend of gradual increase with the increase of water supply level; Under thesame water supply level, soluble solids content of middle N treatment was the highest.7Under subsurface irrigation conditions, orchard mulching treatments were obviouslyeffective on water conservation, and soil water content at different stage was in the followingorder: peat mulching＞wheat straw mulching＞apple branch mulching＞control; Soil watercontent of all the treatments showed a similar seasonal variation trend.8Under subsurface irrigation conditions, orchard mulching treatments increased nutrientcontent in rhizosphere, and peat mulching treatment increased the content of organic matter,total N, available N, NO3--N and NH4+-N most. 9Under subsurface irrigation conditions, orchard mulching treatments increased enzymeactivity in rhizosphere, and peat mulching treatment increased the activity of urease, catalase,saccharase, and phosphatase most.10Under subsurface irrigation conditions, orchard mulching treatments significantlyincreased the quantity of bacteria，fungi, actinomycetes, nitrogen-fixing bacteria, phosphorbacteria, potassium bacteria, cellulose-degrading bacteria and total microbial populations, andalso improved the capacity of rhizosphere microbial community using different types ofcarbon sources, and peat mulching treatment improved the capacity most. Shannon index,Shannon evenness index and Simpson index of orchard mulching treatments weresignificantly higher than control, and were in the following order: peat mulching＞wheatstraw mulching＞apple branch mulching.