Calcium Interference with Zoospore Biology and Infectivity of Phytophthora parasitica in Nutrient Irrigation Solutions

ABSTRACT Calcium, applied as either CaCl2 or Ca(NO3)2 to water or calcium-free soluble fertilizer solution (Peters 20-10-20 Peat Lite Special), affected several important stages of Phytophthora parasitica zoospore behavior relevant to infection and disease spread. Release of zoospores from sporangia was suppressed by Ca(2+) concentrations in the range of 10 to 50 meq. These concentrations also curtailed zoospore motility; 20 meq of Ca(2+) in fertilizer solution caused all zoospores to encyst within 4 h, whereas 94% of zoospores remained motile in unamended solution. In addition, Ca(2+) in the range of 10 to 30 meq stimulated zoospore cysts to germinate in the absence of an organic nutrient trigger, while suppressing the release of a single zoospore (diplanetism) from cysts that did not germinate. In growth chamber experiments, the amendment of the fertilizer solution with 10 or 20 mM Ca(NO3)2 greatly suppressed infection of flood-irrigated, containerized vinca seedlings in a peat-based mix by motile or encysted zoospores of P. parasitica. These results demonstrate that Ca(2+) amendments interfere with P. parasitica zoospore biology at multiple stages, with compounding effects on epidemiology, and suggest that manipulation of Ca(2+) levels in irrigation water or fertilizer solutions could contribute to management of Phytophthora in recirculating irrigation systems.     

不同类型添加材料在新型肥料生产中的应用

就目前新型肥料研制过程中所选用的添加材料或包膜材料进行了归类划分,并对高表面活性矿物、高分子聚合物、抑制剂等材料的化学性质、与肥料养分离子相互作用机理等进行了分析和阐述。分析了不同材料对肥料的溶出速率或释放速率的影响,从提高营养元素有效性和生态环境建设方面讨论了这些材料的应用前景。     

供锌和添加碳酸钙对不同基因型小麦幼苗生长及锌磷吸收的影响

以Hoagland营养液为介质,在不同Zn与CaCO3用量下,将以下5种基因型冬小麦进行营养液混合培养,探讨小麦幼苗生长及Zn与P吸收的状况。根据生长量及缺Zn症状的严重程度,把S02-8、远丰998判定为缺Zn敏感型,而中育6号、小偃22及西杂1号为缺Zn非敏感型;适量供Zn比高量供Zn更有利于小麦生长;低量Ca-CO3可在一定程度上促进小麦幼苗生长而高量CaCO3会抑制生长,缺Zn敏感型的生长量显著低于非敏感型,且前者的根冠比小于后者。加入CaCO3后对小麦植株Zn、P吸收的影响较小,但地上部P/Zn随CaCO3添加量的增加而递减。根系与地上部含Zn量与吸收量均随供Zn量的增加而增加,而高量供Zn时Zn在根部大量累积,同时高Zn用量在一定程度上抑制小麦植株对P的吸收,P/Zn随Zn用量的增加而降低。与不供Zn相比,高量供Zn显著降低了小麦植株根系及地上部的P/Zn值,而低量供Zn时,地上部的P/Zn仅有轻微的降低。供试的5种基因型小麦的P含量均未超过P中毒临界值,因此小麦幼苗出现的缺Zn症状与P无关。相对于缺Zn非敏感型小麦,缺Zn敏感型更易于在根系中累积Zn,吸P量较低,且地上部P/Zn较高。     

低温胁迫下转ICE1基因水稻养分变化的研究

采用盆栽试验,选用转ICE1基因水稻T_4-8株系和T_4-9株系及未转基因水稻（Oryza sativa L.）品种垦鉴稻10号为试验材料,研究苗期低温胁迫对转基因水稻氮、磷、钾养分吸收的影响。结果表明,低温胁迫期间,转基因水稻幼苗丙二醛含量维持在较低水平,SOD活性维持在较高水平;地上部分氮、磷、钾含量变化不大,一直维持在较高水平;地下部分氮、磷、钾含量呈缓慢下降趋势,但降幅比非转基因水稻小,在胁迫第10天,T_4-8株系和T_4-9株系氮含量均高出对照13.86%,磷含量分别高出42.31%和50.00%,钾含量均高出85.71%。说明在低温胁迫条件下,ICE1基因过量表达可以增强水稻的抗寒性,减轻低温对水稻的伤害,保持根系较强的吸收养分能力。     

Factors affecting benfuresate activity against purple nutsedge (Cyperus rotundas L.)

Benfuresate (2-3-dihydro-3,3-dimethylbenzofu-ran-5-yl ethanesulfonate) is a selective herbicide for the control of purple nutsedge in cotton. Under outdoor conditions, purple nutsedge was sensitive to benfuresate incorporated in soil up to eight days after initiation of shoot sprouting from the tuber. Older seedlings recovered from the damage. During the period of susceptibility to benfuresate, young shoots more sensitive than the roots. Under controlled environmental conditions, benfuresate applied directly to apical buds developing from the tuber caused severe damage to the treated bud and induced abrupt development of axillary buds. Negligible amounts of the applied herbicide were translocated from the treated part to the other buds and roots. Application of the herbicide to fully developed leaves had no effect, probably because of its rapid metabolism and low basipetal mobility. Its relatively high volatility may also contribute to its low foliar post-emergence activity. Tubers also absorbed herbicide vapours. Root uptake of ¹⁴C-benfuresate resulted in a rapid accumulation of ¹⁴C in the shoot, which had no effect on the purple nutsedge plant, regardless of concentration. The herbicide is rapidly converted, mainly to a non-phytotoxic polar product. These results may explain the high sensitivity of the weed to benfuresate at early growth stages, and the lack of sensitivity in mature plants.     

Effect of Foliar Application of Urea on Rhizosphere and Rhizoplane Microflora of Wheat1)

The effect of urea leaf treatment on plant growth and rhizosphere microorganisms was studied under controlled environmental conditions with spring wheat at 2 growth stages, and at 2 inorganic nutrient levels of the soil. The increase in dry weight of shoots and roots was inhibited by the urea treatment. Treatment of seedlings also resulted in a delay in the formation of tillers and nodal roots, especially in low fertilized soil. A temporary increase of rhizoplane bacteria was demonstrated after 7–9 days due to a stimulation of fast growing strains. A quantitative effect on rhizoplane fungi was only apparent, on day 9 after treatment of seedlings, as a decrease in total numbers and coincided with the increase in numbers of bacteria and actinomycetes. At this time the numbers of fungi known to be early root colonizers like Penicillium spp. and Mortierella spp. decreased after initially being stimulated, while numbers of late colonizers like Fusarium spp. and Trichoderma spp. increased after 9 days after initially being reduced in comparison with the control. Investigation of the rhizosphere effect (R/S) of wheat by the soil dilution plate method and fluorescence microscopy showed a 200% increase in total numbers of micro-organisms in the rhizosphere soil when the former method was used, but a 10–30% reduction when fluorescence microscopy was employed.     

不同控氮比掺混肥对土壤无机氮与脲酶及冬小麦产量的影响

开展田间小区试验,研究了控释氮肥与尿素掺混施用对土壤无机氮与脲酶及冬小麦产量的影响,旨在寻求控释氮肥与尿素最佳掺混比例,提出缓解氮肥损失、降低面源污染、节约成本、易于推广的施肥方式。结果表明:较常规尿素处理,控释氮肥与尿素掺混对土壤铵态氮含量影响总体差异不显著;在小麦分蘖期,常规尿素处理土壤硝态氮含量和土壤脲酶活性较高,而小麦拔节期至成熟期,则以掺混40%比例以上控释氮肥处理的土壤硝态氮含量和脲酶活性较高;各施氮处理对小麦穗粒数和千粒重影响差异不显著,产量以掺混40%控释氮肥处理最高,较常规尿素处理增产14%,因产值最高,投入成本适中,净收入水平和产投比均为最高,分别为5 875.72元·hm~(-2)和2.24,较常规尿素处理提高了23.24%和9.27%。综上,40%控释氮肥与60%尿素掺混处理在提高土壤无机氮含量,激活小麦生长中、后期脲酶活性,增加冬小麦产量方面效果显著。     

局部根区水分胁迫下钙对冬小麦生长及养分吸收的影响

以小偃22为材料,采用Hoagland营养液进行分根培养试验,研究了局部根区水分胁迫下,钙对冬小麦幼苗生长及养分吸收的影响。设置2个钙水平处理(正常供钙和不供钙)、3种水分处理(正常水分、局部根区水分胁迫和全部根区水分胁迫),共6个处理。结果表明:不论是否水分胁迫,缺钙处理冬小麦幼苗的株高、主根长、生物量、叶绿素相对含量(SPAD值)、相对含水量及地上部N、P、Ca含量和根系N、P、K、Ca含量均显著低于正常供钙处理(P0.05)。正常供钙条件下,局部根区水分胁迫使株高增加4.4%,正常水分、局部根区水分胁迫和全部根区水分胁迫的植株生物量分别为1.54、1.66 g·株-1和0.97 g·株-1,比缺钙处理分别高19.4%、25.8%和4.3%;全部根区水分胁迫下,冬小麦的株高及主根长均显著降低。缺钙条件下,植株对N、P、Ca等养分的吸收显著降低。正常供钙条件下,正常水分、局部根区水分胁迫和全部根区水分胁迫处理地上部全氮含量分别为36.54、36.65g·kg-1和32.70 g·kg-1,比缺钙处理分别高9.5%、6.5%和6.9%;全磷含量分别为7.48、7.51 g·kg-1和6.54 g·kg-1,比缺钙处理分别高3.0%、13.1%和22.7%;全钙含量分别为8.35、8.37 g·kg-1和5.53 g·kg-1,比缺钙处理分别高26.5%、24.4%和19.7%。结果说明钙显著影响冬小麦幼苗生长发育和养分利用,钙可促进局部根区水分胁迫下冬小麦幼苗的生长及其对养分的吸收,缓解全部根区水分胁迫的抑制效应。     

榆阳区农户春玉米施肥现状调查评估

为了解陕北地区施肥现状及农户养分资源投入中存在的问题,2011年通过问卷调查方式,对榆阳区24个乡镇进行了春玉米养分资源投入调查分析。结果表明:2010年春玉米产量以9 500~11 500 kg/hm2所占比例最大且适中,占到调查样本的52.78%。氮肥(N)用量变化为321.8~1 084.3 kg/hm2,平均为650.5 kg/hm2;磷肥(P2O5)用量变化为60.2~450.3 kg/hm2,平均为244.8 kg/hm2;钾肥(K2O)用量变化为47.3~222.8 kg/hm2,平均为134.5 kg/hm2,且钾肥均由有机肥提供。其中化肥氮施用量适中农户仅占5.56%;偏低农户占10.65%;很低农户占5.09%;偏高农户占33.80%;很高农户占44.91%。磷肥施用量适中农户仅占12.04%;偏低农户占21.30%;很低农户占25.46%;偏高农户占19.44%;很高农户占21.76%。春玉米产量与NPK养分总量、氮肥和磷肥用量之间关系极显著,氮肥和磷肥偏生产力分别为24.38 kg/kg和86.94 kg/kg。榆阳区农户春玉米施肥中存在问题主要包括:产量水平差别较大,变化为6 750~15 000 kg/hm2;养分投入差别也较大,肥料利用率很低;肥料品种单一。研究认为提高榆阳区春玉米生产与施肥技术途径有选择优良品种、实现养分资源综合管理,提高养分资源利用效率、加强科学技术的推广应用,提高农民的栽培水平和加大对肥料生产企业的监督检查。     

Establishment and growth of Senecio jacobaea L. and Senecio erucifolius L. in grassland

Senecio erucifolius L. (hoary ragwort) has become conspicuous on roadside verges in southern England. Like Senecio jacobaea L. it is poisonous, so it might be a threat to animal production. In boxed swards the growth of S. jacobaea was less adversely affected by the greater competition from grass with a high level of nitrogen fertilizer than was the growth of S. erucifolius. Also, young S. jacobaea plants showed a much greater ability to regrow after their shoots had been cut at ground level. In a range of grassland managements S. jacobaea established better from seed than did S. erucifolius. Establishment of both species on molehills was poor because of the likelihood that the seedlings would be disturbed or even buried by fresh mole activity. Ten months after sowing, seedlings of S. jacobaea had persisted well in the higher nitrogen environment of ex-cow-dung patches, whereas S. erucifolius had not. Under intensive sheep grazing, in the absence of fertilizer, transplants of S. erucifolius had much greater root dry weights than did those of S. jacobaea. Also, in regrowth after cattle grazing on a fertilized sward, S. jacobaea plants had greater shoot dry weights than did S. erucifolius. Thus, although S. erucifolius can establish from seed in bare patches in an intensively grazed sward it is likely to be less persistent than S. jacobaea if the gaps are ex-dung patches or if nitrogen fertilizer is applied.     

Response of onion (Allium cepa L.) plants to fertilizers, weed competition duration, and planting times in the central Jordan Valley

The competitive ability of onion with weeds and the effects of weeds on onion crop growth and yield were investigated in three field experiments carried out in the central Jordan Valley during the 1997–1998 growing season. Fertilizer application to the onion plants in the presence of weeds significantly lowered the onion yield and reduced the bulb diameter, compared to the unfertilized, weed-infested onion crop. Weed competition and onion yield reduction increased with an increase in the fertilizer rate. All weed-free treatments with or without fertilizer gave a significantly higher onion yield than any of the fertilized, weedy plots. The highest yield of onion was obtained from the weed-free plots with a moderate application of fertilizer. Weed competition reduced the growth, bulb yield, and size of onion in the plots established from bulbs, seedlings, and seeds when compared to the relevant weed-free controls. The effect increased with competition duration and was more pronounced in direct-seeded onion than in the other two types of planting material. However, onion grown from bulbs or seedlings gave better growth, bulb weight, and number and was more competitive than the direct-seeded onion. The results showed that the minimum number of days of weed competition needed for a significant reduction in onion growth was 42 days when propagated from bulbs or seedlings and 21 days after direct-seeding. Onion grown from bulbs tolerated weed competition better and produced a higher bulb yield than that obtained from direct-seeded or transplanted onion, irrespective of the planting dates. December was found to be the best planting time for onion that was grown from bulbs and seedlings, while November was the best planting time for direct-seeded onion, provided the plots were weed-free throughout the growing season.     

Nitrogen fertilization and yield losses of tea to red crevice mite (Brevipalpus phoenicis geijskes) in the Eastern Highlands of Kenya

A field trial using a mite-susceptible clone 11/4 of tea whose yield potential is over 3 t ha^-1 year^-1 was conducted to determine how yield losses due to infestation by red crevice mite (Brevipalpus phoenicis Geijskes) relate to nitrogen nutrition. This was done over a 3 year period in plots either receiving 0, 100, or 200 kg N ha^-1 year^-1. For determining the losses due to mites, an acaricide check method of yield loss assessment was used. Mites were controlled in the plots by spraying flucythrinate. The yield varied considerably between seasons with mean yields in the 3 year period ranging from 2.0 to 2.4 t ha ^-1 without fertilizer and 2.4 to 2.6 t ha^-1 year^-1 at 100 kg N and 2.5 to 2.7 t ha^-1 year^-1 at 200 kg N. Application of the acaricide decreased the mite population by 60-74%. Yield loss between sprayed and unsprayed treatments was 12-22% without fertilizer but this was reduced to 5-6% when fertilizer was supplied at 100-200 kg N ha^-1. The reduction in yield losses in fertilized plots indicate the beneficial effects of nitrogen in inducing tolerance to mites and possibly increasing plant vigour. Protecting the tea from mite attack resulted in yield advantage and a net benefit of $US 0.3, 0.2 and 0.2 per kg made tea at 0, 100 and 200 kg N ha^-1 respectively. Application of 100 kg N ha^-1 had higher net cost benefit than the 200 kg N application rate. The strategy for control of mites would be to integrate spraying with use of fertilizer.     

The influence of water level and nutrient availability on growth and root system development of Myriophyllum aquaticum

Myriophyllum aquaticum is an aquatic plant of still or slow flowing waters. The species mostly occurs in its emerged growth form in dense stands, but submerged shoots can also be found. Due to its rapid growth, M. aquaticum is considered one of the most important aquatic weeds worldwide. In southern Europe, M. aquaticum occurs in irrigation and drainage systems, rice fields and lowland wetlands. In this study, root development and growth response of M. aquaticum to different water levels and nutrient availabilities were investigated in a rhizotron experiment under Central European climatic conditions. The species shows an ability to respond to drained soil conditions by a rapid root growth (up to >1 cm day⁻¹), resulting in a deep root system under drained conditions. In waterlogged soil, the root system spreads more horizontally. Root density increased with increasing nutrient availability. Root:shoot ratio increased significantly with decreasing nutrient availability. In addition, total shoot length, shoot biomass, root biomass and total biomass differed significantly between different water levels and different nutrient availabilities. Relative growth rate increased with increasing water level and nutrient availability. Shoot porosity was higher in nutrient rich substrate than in nutrient low substrate. Root porosity increased with increasing water level. In conclusion, M. aquaticum shows a high tolerance to different water levels, which may be important for future habitat conditions in waterbodies and wetlands in Central Europe under the impact of global change with increased water level fluctuations.     

负载咪鲜胺介孔二氧化硅粒子的制备及性能与安全性评价

介孔二氧化硅粒子 (MSNs) 可作为载体用于制备高载药量的农药缓控释剂,从而实现农药减量化使用和生态环境保护的目的。本研究采用“一锅法”制备了负载咪鲜胺的介孔二氧化硅载药粒子 (prochloraz@MSNs),并对其外观形貌、载药量、释放行为、抑菌作用以及对非靶标生物的安全性进行了系统研究。结果表明:所制备的prochloraz@MSNs呈规则球形,粒径均匀,平均粒径约240 nm,载药量为40.6%,释放速率与pH值和温度相关,酸性、碱性及高温条件均有利于其中咪鲜胺的释放。与常规制剂咪鲜胺乳油相比,prochloraz@MSNs对稻瘟病菌和小麦赤霉病菌的抑制效果更好,持效期更长;对斑马鱼、蚯蚓和人体肺部BEAS-2B细胞的毒性较低。因此,prochloraz@MSNs作为一种高效、低毒、安全的农药新剂型,在植物病害的可持续治理中将具有很好的发展潜力。     

缓控释肥不同施用量和施用方式对旱作区全膜马铃薯生长及产量的影响

为掌握缓控释肥的施用对全膜马铃薯关键生长指标及产量的影响,分别在高(900 kg·hm-2)、中(750 kg·hm-2)、低(600 kg·hm-2)3种施肥条件下进行了2种不同施用方式即集中沟施(F)与表层撒施(B)的田间试验,并测定了马铃薯主要生长指标和产量。结果表明:缓控释肥施用量对旱作全膜马铃薯主要生长指标、产量及商品率的影响均达显著性差异水平,在施用900 kg·hm-2的高肥量时,其沟施处理HF的马铃薯产量、大薯率和商品率均达到最大,分别达43 608.85 kg·hm-2、72.1%和92.7%。施用方式对马铃薯地下主要生长指标、产量和大薯率均表现出显著性差异,且在3种施肥量下,F处理的马铃薯产量、大薯率和商品率均高于B处理,其中在高肥水平下F处理较B处理平均增产达2 834.54 kg·hm-2,增产率为6.4%。施用量×施用方式对马铃薯各生长指标和产量影响均不显著。综合来看,缓控释肥在较高水平的施肥(900 kg·hm-2)条件下,集中沟施处理有利于旱作区全膜马铃薯产量的提高。     

水分对微水溶性胶结包膜肥料氮素释放的影响及其生物学效果研究

采用水基成膜法研制出低成本、易降解的微水溶性胶结包膜缓释肥料.应用性能测试、不同田间持水量下土壤培养及小白菜盆栽试验研究了其养分释放规律与生物学效应,试验表明:微水溶性包膜材料致密、整体厚薄较均一,其吸水性、透水性能优良,且具一定的生物降解性能.在田间持水量50%、60%、70%条件下,微水溶性胶结包膜缓释肥料土壤铵态氮含量变化与水分呈正相关关系,24 d后硝态氮含量呈高于尿素处理趋势.在田间持水量50%、60%、70%三种水分条件下,微水溶性胶结包膜肥料处理油菜产量均高于尿素处理,在70%田间持水量下达到了显著差异(P<0.05);微水溶性胶结包膜肥料处理增加了Vc含量,但没有显著增加油菜含氮量、硝酸盐含量和叶绿素含量.     

保水缓释钙肥的特征与性能

采用化学聚合反应将保水剂与硝酸钙聚合为一体化物质,并以吸水倍率、p H值、土壤水分特征曲线、元素分析、红外光谱、电子显微镜及7 d溶出率法表征保水钙肥的吸水持水能力、化学性质、形貌结构及养分释放性能。结果表明:保水缓释吸水倍率约为165 g·g-1,含钙量为103 g·kg-1,p H值近中性;保水剂通过化学键结合,基质包埋负载钙盐;网络孔隙及基质是保水钙肥吸水保水的物理结构;与对照相比,保水钙肥添加量为1%时,在测试吸力段可增加土壤容积含水量平均14.0%。此外,保水钙肥显示较好的钙素养分延缓释放性能,可将钙素较长时间保持在水凝胶基质内而延长水溶性钙有效期。     

Growth of seedlings of Agropyron repens (L.) Beauv. and Agrostis gigantea Roth in cereal crops

Experiments were undertaken to define the conditions under which seeds and seedlings of Agropyron repens and Agrostis gigantea may start infestations in cereal crops. When seedlings were planted early or late in spring wheat and spring barley, most growth of shoots and rhizomes was produced by Agropyron planted early in wheat. Late planting halved the amount of shoot growth and severely inhibited rhizome formation. In winter wheat given a moderate or zero amount of nitrogen fertilizer in spring, growth of the weed seedlings was slow. Rhizomes were not produced during the time the crop was growing but only after harvest. Agrostis made more growth than Agropyron in most treatments throughout most of the experiment. Late planting decreased growth more than in the spring cereals. Nitrogen fertilizer, although it had little effect on the amount of growth made by winter wheat, increased the growth of the early-planted seedlings but decreased that of the late-planted ones of both weed species. When planted into plots given nitrogen, more seedlings of both species died after late than after early planting. Clearly, the amount of growth and rhizome produced by seedlings of these two species will depend on the type of cereal, the time of emergence of the seedlings in relation to the cereal, and on other factors affecting the relative vigour of cereal and weed. Evidently, where the weed seedlings emerge early in weakly or moderately competitive cereal crops or when growth is unchecked in the cereal stubble, seedlings could give rise to infestations.     

Fate of carbendazim in rice tissues after seed or foliage treatments

Carbendazim was quantified employing reversed-phase high-performance liquid chromatography in rice coleoptiles, radicles and shoot portions of seedlings of different ages grown from seeds treated with the fungicide, and in shoot portions of adult plants at different times after foliar treatment with the fungicide. The highest levels of carbendazim were detected in the coleoptiles four days after germination of seeds and the radicals contained the lowest concentrations. Carbendazim residues declined with time in the shoot portions of seedlings and of adult plants. However, the levels of carbendazim detected in the shoot tissues of 21-day-old seedlings grown from treated seeds [recommended dose of 10 mg a.i. 10g^?1 seeds] and in adult plants 35 days after treatment (recommended dose of 0.25 g a.i. litre^?1 spray fluid) correspond to the reported lasting ability of the fungicide in terms of protection against blast of rice.     

控释尿素与普通尿素配施对春玉米产量、氮肥利用及经济效益的影响

在黄土高原东部春玉米主产区连续3 a开展大田定点试验,设置不施氮（CK）、控释尿素与普通尿素不同配比：0（CRU0%）、25%（CRU25%）、50%（CRU50%）、75%（CRU75%）、100%（CRU100%）共6个施肥处理,研究控释尿素与普通尿素不同配施比例对春玉米产量、氮素利用和经济效益的影响,并建立控释尿素配施比例与产量、氮肥表观利用率和施肥收益之间的关系,以确定最佳配施比例,为筛选适于在黄土高原东部推广应用控释掺混配方肥提供科学依据。研究结果表明：（1）控释尿素与普通尿素配施能显著提高玉米产量,增加施肥收益,且随着配施比例的增加,2项指标均呈先增加后降低的趋势,其中CRU75%处理的春玉米产量和施肥收益最高,分别较CRU0%处理增加了1 273 kg·hm^-2（11.9%）和1 735元·hm^-2（65.7%）。（2）与CRU0%处理相比,控释尿素不同配施比例处理显著提高了玉米氮素利用率、农学效率和偏生产力,提高幅度依次为24.73%~43.87%、38.22%~61.24%和7.45%~11.93%,且均以CRU75%处理最高。（3）控释尿素与普通尿素配施处理显著降低了0~100 cm土层土壤中氮残留量和氮素表观损失量,CRU75%处理氮残留量和氮表观损失量最低,分别为119.8 kg·hm^-2和247.5 kg·hm^-2。（4）控释尿素配施比例与春玉米产量、氮肥表观利用率和施肥收益均存在显著一元二次关系,基于此3项指标推算出控释尿素的适宜配施比例分别为64.3%、71.2%和61.8%。控释尿素与普通尿素配合施用有利于促进春玉米生长发育,获得增产增收并提高氮素效率,综合各因素确定黄土高原东部春玉米生产的控释尿素适宜配比为60%~75%。