Effects Of Different Nitrogen Levels On Carbon And Nitrogen Nutrition Utilization And Allocation On Interstock Apple Tree

Dwarf rootstock efficient intensive cultivation is a new developing trend of appleindustry with the dwarfing interstocks using the most widely. Since the backward oncultivation technique study and the vigorous growth and premature senescence of theinterstock making the robust growth of interstocks consistent with timely flowering andbearing is the heart of management, which needs to study deep into the nutritioncharacteristics on carbon and nitrogen of interstocks. Therefore, double labelling technique of¹⁵N and¹³C stable isotopes was used to study the effect on growth and development and thecarbon and nitrogen nutrition of SH₁₈、SH₂₈、SH₃₈、SHc、CG₂₄and Mark, the yearly C、Nutilization characteristics of different nitrogen levels of commonly-used Fuji/M₂₆/M.hupehensis Rehd.in production, and effects of pinching and old leaf picking on growth andcarbon and nitrogen nutrition of Borkh cv. Fuji/SH1/Malus robusta Rehd. and Borkh cv.Fuji/SH6/M. hupehensis Rehd., in order to provide evidence for high quality and yieldcultivation technique of trees with interstocks. The main results were as follows:1.C、N characteristics of different nitrogen levels on young apple trees with differentinterstocks: the testing interstocks were classified into three different types based onclustering analysis of biomass: CG₂₄has the strongest effect on growth inhibition, while SH₂₈the weakest, and SH₁₈、SHc、SH₃₈and Mark showed medium inhibition effect. Significantdifferences can be found on biomass of different nitrogen levels on young apple trees, of theno nitrogen （N0）、proper nitrogen（N100）and over-dose nitrogen（N200）treatment, biomassof SH₂₈increased with the increasing application of nitrogen, while biomass of the other treesshowed the best results with the proper amount of nitrogen application, and continuousapplication of nitrogen existed inhibition effect, indicating that proper amount of nitrogen isessential for the promotion of young apple tree with strongly inhibition interstocks.Significant differences can be seen on¹⁵N utilization and distribution of various nitrogenapplication,¹⁵N utilization rate of trees with interstock SH₂₈increased with the increasingapplication of nitrogen,and the¹⁵N is mostly distributed into the aboveground, while the root¹⁵N distribution rate decreases; however, trees with interstock CG₂₄and SH₃₈shows thehighest¹⁵N utilization rate with the treatment of proper amount of nitrogen; and¹⁵Ndistribution differs significantly:¹⁵N is mostly distributed to the root of CG₂₄with over-doseapplication of nitrogen, while the aboveground¹⁵N distribution rate decreased, the¹⁵N distribution into aboveground of CG24was superior to root system in the treatment of nonitrogen application and proper nitrogen application;¹⁵N of trees with interstock SH₃₈wasmostly distributed to root system with proper nitrogen application, and the¹⁵N distributionrate of aboveground was superior to root system in the treatment of no nitrogen applicationand over-dose application of nitrogen.¹³C distribution rate of different nitrogen levels on treeswith various interstocks differs significantly:¹³C was mostly distributed to aboveground intrees with interstock SH₂₈with the treatment of over-dose nitrogen application, while¹³Cdistribution rate of the root system decreased;¹³C distribution rate of aboveground wassuperior to root system with the treatment of no nitrogen application and proper nitrogenapplication;¹³C was mostly distributed to aboveground in trees with interstock SH₃₈with theincreasing application amount of nitrogen;¹³C distribution of different nitrogen levels on treeswith different interstocks differs significantly,¹³C was mostly distributed to aboveground intrees with interstock SH₂₈under the treatment of over-dose nitrogen application, and¹³C of theroot system decreased, and¹³C distribution into aboveground was superior to root system inthe treatment of no nitrogen application and proper nitrogen application;¹³C was mostlydistributed to aboveground with interstock SH₃₈under the increasing application amount ofnitrogen, and the¹³C distribution rate of rootstock decreased; in trees with interstock CG24,¹³C is mostly distributed to the aboveground under proper nitrogen application (¹³Cdistribution rate of root being the lowest17.63%), and then no nitrogen treatment,while theover-dose application of nitrogen showed the lowest¹³C distribution rate(¹³C distribution rateof root being the highest27.14%).2. Study on annual cycle of carbon and nitrogen characteristics of Yantai Fuji3/M₂₆/M.hupehensis Rehd.: Biomass during autumn shoots growth period under different nitrogenlevels showed that M₂₆interstock is the type of strong inhibition. According to their annualcycle effects under different nitrogen levels, no obvious difference were found above thosethree treatments during the stage of vigorous growth of spring shoots. With the increase ofnitrogen levels, the biomass also increased; at spring shoots growth arrest stage, the biomassof medium nitrogen and excess nitrogen were higher than the treatment with no nitrogen, andthere were significantly differences among those three treatments, with the increase ofnitrogen, the biomass also increased; however at autumn shoots growth period, the biomass ofmedium nitrogen was the highest. Compared to over-dose nitrogen, the biomass of mediumnitrogen has changed at autumn shoots growth period, this related to the fine root biomass ofmedium nitrogen is higher than that of excess nitrogen. About the respect of utilization anddistribution of¹⁵N, although the utilization of medium nitrogen was the highest, no nitrogen was the highest during the stage of vigorous growth of spring shoots, until to spring shootsgrowth arrest stage, medium nitrogen was the highest. With the development of growth period,every treatment showed that the distribution of¹⁵N of root was decreased, with aerial partincreased. The treatment of no nitrogen, the distribution of¹³C of root increased, while aerialpart decreased; those were contrary to the treatment of medium nitrogen and over-dosenitrogen treatment. Medium nitrogen could keep balance of C and N metabolism, madecarbon and nitrogen assimilated broaden and deepen the optimization between abovegroundand underground portion, this could promote tree growth next year. Starch content wassignificantly related to flower formation, In this study, starch content and ABA content ofleaves were the highest in the treatment of no nitrogen. Therefore the distribution and storageform of photosynthetic products were caused by ABA synthetic differences.3. C、N characteristics of pinching on apple trees with different interstocks: Study onfour-year-old Borkh cv. Fuji/SH1/M. hupehensis Rehd. and one-year-old Borkh cv.Fuji/SH6/Malus robusta Rehd. showed that pinching significantly inhibited the tree vigorcompared with control, and decreased the uptake of nitrogen and the carbon fixationsignificantly, while increased¹³C and¹⁵N distribution rate on storage organs significantly, anddecreased the ratio of new organs（leaves, shoot and fine roots） significantly; IAA contents ofleaves significantly decreased, while the ABA contents significantly increased.4. C、N characteristics of picking old leaf on young apple trees: with old leaves pickingon one-year-old Borkh cv. Fuji/SH6/Malus robusta Rehd., results showed that, picking oldleaves could significantly improve the growth of center stem compared to control, the carbonfixation significantly reduced, with no obvious difference can be seen on the uptake ofnitrogen. The¹³C and¹⁵N distribution rate on neonatal organs（leaves and shoot） significantlyincreased, with the ratio of storage organs significantly decreased; ABA contents of leavesgradually reduced, while GA3contents gradually increased.