不同施氮水平对矮化富士苹果幼树生长、氮素利用及内源激素含量的影响

Effect of different N application rates on plant growth,^(15)N-urea utilization and hormone content of dwarf apple trees

【目的】矮化中间砧是目前我国苹果栽培中主要的致矮手段,但在提早结果的同时存在树势早衰的现象,而有关矮化中间砧的果树氮素需求规律及其氮素与树体生长和内源激素之间的关系研究较少。本文研究氮素施用量对矮化中间砧苹果幼树的生长、氮素吸收利用及内源激素的影响,以期为苹果矮化中间砧的果树栽培中氮肥的科学施用和高效利用以及防止树体早衰提供理论依据。【方法】利用15N同位素示踪技术,以三年生宫藤富士/SH6/平邑甜茶(Borkh cv.Fuji/SH6/M.hupehensis Rehd)为试材,于春梢萌芽前,设置3个氮肥施用水平(N 50、100、200 kg/hm2,分别以N50、N100、N200表示),同时每棵树施15N-尿素0.5 g。于春梢旺长期、春梢缓长期,采用酶联免疫法测定茎尖和细根的激素含量;植株停止生长时,测其春、秋梢长度,并整株解析,称量各部分鲜重、干重,测植株全氮及其15N丰度。【结果】研究结果表明,不同施氮水平与植株生长及氮素吸收利用密切相关,春、秋梢长度、树体鲜重及植株全氮均以N50处理最低,N100次之,N200最高,但15N的利用率趋势正好相反,为N50>N100>N200;细根鲜重以N100处理(34.06 g)最高,N200(28.36g)次之,N50(22.47g)最低。施氮水平对茎尖和细根的赤霉素(GA)、玉米素核苷(ZRs)、脱落酸(ABA)和吲哚乙酸(IAA)的含量变化及其比值有较大影响。春梢旺长期和春梢缓长期茎尖、细根中的IAA和GA含量均为N50<N100<N200,而ZR和ABA的含量则随氮肥用量的增加而降低,表现为N50>N100>N200;春梢缓长期与春梢旺长期相比,除细根中GA含量(N50、N100、N200处理分别为5.13、5.68、6.17 ng/g,Fw)有所升高外,各器官的IAA、GA、ZR的含量均明显降低,且差异显著;两时期茎尖和细根的ZR/GA、ABA/GA比值均以N50处理最大,N100处理次之,N200处理最小;同一器官不同处理间(IAA+GA+ZR)/ABA比值也存在差异,N200处理显著高于其他处理。【结论】氮肥施用量在50 kg/hm2到200 kg/hm2范围内,随着氮肥用量的增加矮化中间砧苹果幼树的生长促进型激素含量、植株全氮和植株生物量显著增加,但15N利用率显著降低,且ZR/GA、ABA/GA比值逐渐降低。本试验条件下施氮量为N100 kg/hm2是矮化中间砧苹果幼树的适宜施氮量,有利于提高氮素利用率,促进细根生长,同时可延缓树势衰老,促进成花,保证苹果矮化密植集约化栽培中的氮肥充足和均衡供应。

[Objectives] The dwarfed interstocks are been used to realise the dwarfed apple cultivation, which facilitate early fruiting whereas might lead to presenility of apple trees. Few studies have been focused on the demand of nitrogen as well as the relationship between growth and endogenous hormone of dwarfed interstocks. Thefore, effects of different nitrogen application levels on growth, nitrogen uptake and utilization and endogenous hormone of dwarfed interstocks were studied. [Methods]Using the 15 N isotope tracer technique, three-year-old＆amp;nbsp;Fuji/SH6/Malus hupehensis Rehd was selected as test materials. Threre were three N application rates, 50 kg/hm2 , 100 kg/hm2 and 200 kg/hm2（ N50 , N100 and N200 ） . At the shoot vigorous growing period and slow growth period, the hormones in stem tips and fine roots were measured using enzyme-linked immunoassay（ ELISA） . In the shoot stop growing, the length of the spring shoots and autumn shoots was measured, then whole plants were parsed, fresh weight and dry weight of each part were weighed, and the plant total nitrogen and 15 N abundance were determined. [Results]The results show that the plant growth and nitrogen uptake are significantly related to the N application levels. The total fresh weight, fine root biomass and total N content of the plants in the N50 treatment are the lowest, followed by N100 treatment, while those in the N200 treatment are the highest. The utilization rates of 15 N are just the opposite, N50〉N100〉N200 . The N application has great influence on dynamic changes and values of GA, ZR, ABA and IAA. During the vigorous growing period and slow growth period of the shoots, the contents of IAA and GA in stem tips and fine roots are as follows：N50〈N100〈N200 , but the contents of ZR and ABA are declined along with the increase of nitrogen：N50〉N100〉N200 . Compared with the vigorous growing period, except that the contents of GA of fine roots（N50 is 5. 13, N100 is 5. 68 and N200 is 6. 17 ng/g, FW）are increased , the contents of IAA、GA and ZR in each organ are significantly reduced during the slow growth period of shoots. In the two periods, the ratios of ZR/GA and ABA/GA in stem tips and fine roots are the highest under N50 treatment, followed by the N100 treatment, and the ratios of the N200 treatment are the lowest. The values of （ GA＋ZR＋IAA）/ABA of different N application rates are different in the same organs, meanwhile the ratio of the N200 treatment is significantly higher than those of other treatments. [Conclusions]With the increase of nitrogen fertilizer in the range of N 50 kg/hm2 to 200 kg/hm2 , hormones, total nitrogen and biomass in dwarfed interstock apple saplings are increased significantly, while the 15 N utilization rate, ZR/GA and ABA/GA ratios are gradually reduced. In this study, the appropriate amount of nitrogen application for apple trees is recommended as 100 kg/hm2 , it could promote the growth of fine roots and the utilization of nitrogen, delay senescence and promote flowering , ensure sufficient and balance supply of nitrogen in intensive cultivation in dwarfed apple under this condition.