Diagnostic of the nutritional status in fruit trees can be estimated using different models. However, these models usually do not fully match the character of the perennial crops and their accuracy needs to be improved. This study aimed at deepening the understanding of the aspects controlling mineral content of macro- and micronutrients and fruit quality of the apple trees with respect to the crop load and vegetative shoot growth. The focus was given on description of the nutrient content variability in time and space, its relation to important physiological events, and conditions altering their gradient in leaf and fruit. The evaluation was carried out with six years old ’Golden Delicious’ apple trees on M9, planted in an experimental orchard. Flowering rate, total yield, shoot growth intensity, mean fruit weight and quality along with mineral content of leaves, and fruit in different development stages were analysed according to intensity of natural or regulated flowering and fruit set, respectively. We found that aside of macroelements, iron, and manganese depended on the crop load. For nitrogen, phosphorus, and potassium content, their gradient increased up to 10–25% within the sufficiency range as the trees tried to maintain certain level of these nutrients in leaves and fruit simultaneously during deficit. In contrary, the higher content of Mg, Fe, and Mn related to the avoidance of deficit through up to 20–30% higher uptake in trees with higher crop load. Phosphorus, potassium, and calcium content in short fruiting shoots was more stage dependent, showing relation with the timing of cessation of particular meristematic growth activity. If no intense deficit occurred, the trees kept unrestricted initial investment of nutrients in the fruit during cell division stage whatever the crop load was. Their content at the later development stages appeared to be more dependent upon the consumption by particular sink. These findings allowed to improve the interpretation of the fruit trees nutrition status due to adaptation of the reference nutrient content in low cropping trees by a reduction of 5–10% N and P, 10–15% Ca, as well as by an increase of 15–20% K content in leaves at the stage with fruit size of 20 mm, and without change in P content at the stage of about 70% of final fruit size.

Environmentally sound management of N in apple orchards requires that N supply meets demand. In 1997, newly planted apple trees (Malus domestica Borkh. var. Golden Delicious on M.9 rootstock) received daily applications of N for six weeks as Ca(15NO3)(2) through a drip irrigation system at a concentration of 112 mg l(-1) at 2-8, 5-11 or 8-14 weeks after planting. Irrigation water was applied either to meet estimated evaporative demand or at a fixed rate. In 1997, trees were harvested at 5, 8, 11 and 14 weeks after planting; and in 1998 at 3 weeks after full bloom. The amount of fertilizer N recovered was similar in trees in both irrigation treatments, but efficiency of fertilizer use was greater for trees receiving demand-controlled irrigation than fixed-rate irrigation. This was attributed to lower N inputs, greater retention time in the root zone and less N leaching in the demand-controlled irrigation treatments compared with fixed-rate irrigation treatments. Less fertilizer N was recovered by trees receiving an early application of N than a later application of N and this was related to the timing of N supply with respect to tree demand. Demand for root-supplied N was low until 11 weeks after planting, because early shoot and root growth was supported by N remobilized from woody tissue, which involved 55% of the total tree N content at planting. Rapid development of roots > 1 mm in diameter occurred between 11 and 14 weeks after planting, after remobilization ended, and was greater for trees receiving an early application of N than for trees receiving a later application of N. Late-season tree N demand was supplied by native soil N, and uptake and background soil solution N concentrations were higher for trees receiving demand-supplied irrigation compared with fixed-rate irrigation. Total annual N uptake by roots was unaffected by treatments and averaged 6-8 g tree(-1). Nitrogen applications in 1997 affected growth and N partitioning in 1998. Trees receiving early applications of N had more flowers, spur leaves and bourse shoots than trees receiving later applications of N. Consequently, more N was remobilized into fruits in trees receiving early applications of N compared with fruits in trees receiving later applications of N. Demand for N in the young apple trees was low. Early season demand was met by remobilization from woody tissues and the timing of demand for root-supplied N probably depends on whether flowering occurs. Method of N delivery affected the efficiency of N use. We conclude that N demand can be met at soil solution N concentrations of around 20 mg l(-1).

Optimizing the utilization of applied nitrogen (N) in fruit trees requires N supply that is temporally matched to tree demand. We investigated how the timing of N application affected uptake, allocation, and remobilization within 14-year-old “Gala”/M26 apple trees (Malus domestica Borkh) over two seasons. In the 2017–2018 season, 30 g N tree−1 of 5.5 atom% 15N–calcium nitrate was applied by weekly fertigation in four equal doses, commencing either 4 weeks after full bloom (WAFB) (pre-harvest) or 1-week post-harvest, or fortnightly, divided between pre- and post-harvest (50:50 split). Nitrogen uptake derived from fertilizer (NDF) was monitored by leaf sampling before whole trees were destructively harvested at dormancy of the first season to quantify N uptake and allocation and at fruit harvest of the second season to quantify the remobilization of NDF. The uptake efficiency of applied N fertilizer (NUpE) was significantly higher from pre-harvest (32.0%) than from the other treatments (~17%). The leaf NDF concentration, an indicator of N uptake, increased concomitantly only when pre-harvest N was applied. Pre-harvest treated trees allocated more than half of the NDF into fruit and leaves and stored the same amount of NDF into perennial organs as the post-harvest treatment. Subsequent spring remobilization of NDF was not affected by the timing of N fertigation from the previous season. A seasonal effect of remobilization was observed with a decrease in root N status and a reciprocal increase in branch N status at fruit harvest of season two. These findings represent a shift in the understanding of dynamics of N use in mature deciduous trees and indicate that current fertilizer strategies need to be adjusted from post-harvest to primarily pre-harvest N application to optimize N use efficiency. This approach can provide adequate storage N to support early spring growth the following season with no detriment to fruit quality.

以6年生烟富3/SH6/平邑甜茶为试材,用整株破坏性解析的方法,研究了萌芽期至果实成熟期7个时期下的树体生长和氮素积累动态,并借助¹⁵N同位素示踪技术研究了树体对肥料氮的吸收利用和分配特性,以期阐明苹果树的氮积累动态和肥料氮的最大效率期,从而为科学施氮提供理论依据.结果表明: 萌芽期(3月25日)至果实成熟期(萌芽后210 d)红富士苹果幼树整株干物质净积累量为4.51 kg,其中果实占66.5%,叶梢(叶片与新梢,下同)占20.2%,多年生器官占13.3%;叶梢干物质积累量在萌芽后30～60 d增长幅度较大,占其整个处理时期的42.9%;果实干物质积累量在萌芽后120～180 d增长幅度大,占整个处理时期的70%.整株氮素净积累量为29.1 g,在萌芽后30～60 d和120～180 d增长较快,分别为7.2和12.8 g,占整个处理时期的24.7%和44%;叶梢在萌芽后0～60 d氮积累速率较快,占其整个时期的69.1%;果实的氮积累量在萌芽后120～180 d最快,占其整个时期的60.8%;多年生器官的氮积累量在处理周期内呈先下降后上升的趋势,并在萌芽后 60 d到达最低水平.树体在不同时期的¹⁵N利用率差异显著,分别在萌芽后30～60、120～150和150～180 d处于较高水平,¹⁵N利用率分别为2.3%、4.1%和4.0%;多年生器官在各个时期的¹⁵N分配率均呈现较高水平,新生器官的¹⁵N分配率均为先上升后下降的趋势,其中叶片新梢在萌芽后30～60 d达到最高水平,为38.4%;果实在萌芽后120～150 d和150～180 d到达最高水平,分别为15.0%和16.6%.因此,叶片和新梢氮素积累的关键时期为萌芽后30～60 d;果实氮素积累的关键时期为萌芽后120～180 d;树体对肥料氮的最大效率期为萌芽后30～60 d和120～180 d.

以‘天红2号’苹果为试材，研究不同砧木短枝和中枝在花芽分化期间叶片和枝条中10种矿质元素变化情况。结果显示，无论嫁接在SH40中间砧还是八棱海棠乔砧上，稳产期‘天红2号’苹果成花率无差异，叶片和枝条中矿质元素含量变化趋势相似。在整个花芽分化期，叶片中氮、磷、钾、锰、硼和锌（短枝）含量呈下降趋势，钙含量呈上升趋势，铜含量波动性变化，铁含量呈降-升-降-升的变化；枝条中氮、钾、镁、锰、硼和锌（中枝）含量呈下降趋势，磷和钙含量呈上升趋势，铁含量呈升-降-升的变化。短枝和中枝叶片中氮、钾、镁、锰和硼含量高于枝条，钙、铜和锌含量低于枝条。成花率高的短枝枝条氮、磷、钙、镁、铁、硼和锌含量高于成花率低的中枝枝条；短枝叶片钙、镁和铜含量高于中枝叶片。

矿质元素是影响果树生长发育､产量形成和品质指标的物质基础｡通过收集和测定苹果叶片矿质元素含量,研究了胶东半岛富士苹果叶营养元素标准值及其分布规律｡结果表明:胶东半岛富士苹果叶片N､P､K､ Ca､Mg和Cu 6种矿质元素的分布分别遵从N~N(24.624,2.41²)､P~N(2.03,0.45²)､K~N(14.95,3.68²)､ Ca~N(16.11,5.12²)､Mg~N (4.12,1.02²)和Cu~N(72.84,38.40²)的正态分布,其余4种元素B､Fe､Mn､ Zn呈近似χ² 偏态分布｡对于符合正态分布的6种元素,采用4点5级的概率分级方法,依次划分缺乏､低值､正常值､高值､过高5组数据相对应的分布范围｡对于偏态分布的4种元素,参照国内外叶营养标准值,通过概率分级进行校正,使缺乏和过高的叶样占总样的10%左右,低值和高值的叶样占总样的20%左右,正常值范围的叶样占总样的40%左右｡据此制定出胶东半岛富士苹果叶营养元素的标准值范围:N 23.36~25.88g/kg,P 1.79~2.27g/kg,K 13.02~16.88g/kg,Ca 13.42~18.80g/kg,Mg 3.58~4.66g/kg,Cu 52.67~93.01mg/ kg,Fe 121~150mg/kg,B 27~35mg/kg,Mn 161~300mg/kg,Zn 23~28mg/kg｡与国内其它地区标准值相比,胶东半岛富士苹果的叶营养元素含量标准值表现出Cu和Mn偏高,Ca､Fe､Zn偏低,N､P､K､Mg和B表现较为相似｡

【目的】 研究阿克苏地区红旗坡农场长富2号和烟富6号苹果不同成熟期的果实中,矿物质含量和可溶性糖含量变化的关系,为苹果优质丰产栽培提供理论基础。【方法】 以长富2号和烟富6号为材料,研究不同成熟期果实内矿物质元素和可溶性糖组分之间的相互关系,采用高效液相色谱仪,测定可溶性糖种类和含量,利用凯氏定氮法、钒钼黄比色法、火焰光度计法、原子吸收分光光度、法姜黄素比色法测定果实中的矿物质元素。【结果】 9月16日,长富2号和烟富6号的蔗糖、葡萄糖和山梨醇含量分别是20.12和36.4 mg/g,33.82和18.29 mg/g,3.52和4.68 mg/g,存在显著差异,在10月5~25日期间2品种的果糖含量分别是71.50和90.43 mg/g,91.64和78.69 mg/g,94.48和82.52 mg/g,均达到显著水平显著差异。长富2号果实中的N、Ca、Cu、Fe和Zn含量在9月16日~10月25日一直处于下降趋势,N含量与Ca、Cu、Fe含量呈显著正相关,蔗糖与Ca、Cu、Fe呈显著负相关,与Zn含量呈极显著负相关,在烟富6号中Ca元素与山梨醇呈显著负相关,Mg和Fe元素对蔗糖呈极显著正相关,B元素与果糖呈极显著负相关。【结论】 10月15日,长富2号的葡萄糖和山梨醇含量达到最大值,烟富6号此时的葡萄糖含量也是最高的。10月25日,2品种的蔗糖含量达到最高值。长富2号的果糖含量也达到最大值,烟富6号在10月5日达到最大值。长富2号全磷和B含量在10月5日达到最大值,全钾含量在10月15~25日上升,Mg含量在此期间处于下降趋势,9月16日~10月25日,全氮、Fe、Ca、Cu和Zn含量一直处于下降趋势。烟富6号中全氮含量从9月16日~10月25日期间,呈‘S’型增长,Ca、Cu和Zn含量在此期间处于下降状态,10月15~25日期间全磷、Fe、Mg含量不断上升,全钾含量在此前间下降。

The nutrient accumulation curves of apple trees are good indicators of plant nutrient demand for each developmental stage. They are also a useful tool to evaluate orchard nutritional status and to estimate the amount of soil nutrient removal. This research aimed at evaluating the seasonality of nutrients in commercial apple orchards during the agricultural years of 1999, 2000, and 2001. Therefore, apple tree leaves and fruits of three cultivars 'Gala', 'Golden Delicious' and 'Fuji' were weekly collected and evaluated for fresh and dry matter, fruit diameter and macronutrient (N, P, K, Ca and Mg) and micronutrient (B, Cu, Fe, Mn, and Zn) concentrations. Leaf and fruit sampling started one or two weeks after full bloom, depending on the cultivar, and ended at fruit harvest or four weeks later (in the case of leaf sampling). In general, leaf concentrations of N, P, K, Cu, and B decreased; Ca increased; and Mg, Fe, Mn, and Zn did vary significantly along the plant vegetative cycle. In fruits, the initial nutrient concentrations decreased quickly, undergoing slow and continuous decreases and then remaining almost constant until the end of fruit maturation, indicating nutrient dilution, once the total nutrient accumulation increased gradually with fruit growth. Potassium was the nutrient present in highest quantities in apple tree fruits and thus, the most removed from the soil.

The proper use of potassium fertilizer can stimulate a significant yield increase. However, the application of excessively high rates of potassium can reduce the availability of soil calcium for apple trees. The potassium fertigation rate must meet the apple tree’s requirements so that the applied fertilizers can be absorbed by the roots as much as possible. Crop load in apple orchards sometimes varies significantly in different years. The potassium content in apple fruits is relatively high, and the maximum requirement for this nutrient occurs when fruits grow and ripen. Different crop loads at that time mean the various demands of trees and need for changing application rates for this nutrient. The investigation was carried out in the experimental orchard of I.V. Michurin Federal Scientific Centre (Michurinsk, Russia) in 2016 and 2017 (52.885131, 40.465613). We studied seasonal changes of potassium and calcium contents in soil, fruits, and leaves and their relationship with yield during the research. We paid much attention to the potassium rate shift on its content in leaves and fruits and cultivars “Lobo” and “Zhigulevskoye” yield. If the potassium application rate changes according to the actual crop load, it stimulates the yield growth or (if the crop load was relatively low) the reduction of the rate did not lower the productivity. Moreover, we studied the relationship between potassium and calcium nutrition. The decrease in potassium fertigation rate increased the availability of soil calcium. It was the reason for fruit calcium concentration enlargement and mitigation of the K/Ca ratio. We also specified some parameters for soil–leaf diagnosis for potassium nutrition during the growing season.

在中国贫瘠的果园土壤条件下，化肥在苹果增产过程中发挥了重要作用，同时不合理的化肥使用也带来了肥料利用率低、果实品质下降、土壤质量降低、水体富营养化和温室气体排放等问题。因此，科学施肥提高化肥利用率，减少由于化肥损失带来的环境污染是关系到苹果产业能否实现绿色可持续发展的重大科技问题。分析了中国苹果养分管理中存在的问题，综述了当前已有的苹果化肥减量增效技术，主要包括障碍性土壤改良与培肥地力、最佳养分管理、根层养分调控和新型肥料与“大配方、小调整”区域配肥技术，并对今后苹果化肥减量增效技术的研究进行了展望。

缓/控释肥料是21世纪肥料发展的重要方向,对维护中国粮食安全、提高肥料利用率,实现农业生产与生态协调发展、节本增效和节能减排等方面均具有十分重要的意义。本文在总结缓/控释肥定义、作用机制、研究现状的基础上,阐述了缓/控释肥在农业生产中的应用效果和在应用及推广中存在的问题,提出了相应的对策和建议,展望了缓/控释肥的发展前景,以期为缓/控释肥的研究提供理论依据。