红壤不同地力条件下直播油菜对施肥的响应

2009至2010年度在江西、湖南两省的典型红壤区设置8组直播油菜氮磷钾硼肥田间肥效试验,旨在研究红壤不同地力条件下直播油菜对施肥的响应,探寻养分限制因子。结果表明,红壤直播油菜的长势受到地力的显著影响,高、中、低地力田块基础地力产量(不施肥处理产量)平均分别为1230、721和191kg hm-2。施肥不同程度促进了直播油菜的生长发育,养分吸收与累积,提高了籽粒产量并影响收获指数,各地力田块均以氮磷钾硼配施(NPKB)处理最好,其高、中、低地力田块平均产量分别为2529、1681和1065 kghm-2,产量水平随地力上升而大幅提高,但增产率则呈下降趋势。在其他养分配施基础上增施不同肥料的增产增收效果顺序为N>P>B>K,表明红壤直播油菜的养分限制因子依次为氮、磷、硼和钾,但受土壤养分状况差异的影响,不同地力条件下施肥的效果也存在差异,低地力田块施肥的相对增产效果好,绝对增产量及施肥收益仍以高地力田块较好。红壤区直播油菜的氮、磷、钾肥吸收利用率平均分别为34.5%、26.7%和65.4%,且各肥料利用率随地力上升而提高。试验结果说明,红壤区直播油菜的养分管理应重视氮磷钾硼肥的配合施用,缓解养分限制,从而有效增产。通过长期合理施肥以培肥土壤、提高地力,达到持续高产稳产。     

Drip fertigation with nitrogen and potassium and postharvest susceptibility to bacterial soft rot of bell peppers

In 1991 and 1992, drip irrigation was used to apply various rates and timings of nitrogen (N) and potassium (K) to black polyethylene plastic‐mulched bell pepper (Capsicum annuum L.) to determine the effect on fruit quality and susceptibility to postharvest bacterial soft rot (Ervinia carotovora subsp. carotovora). Neither rate nor application timing affected total yield in either year. In 1991, the high fertilizer rate (266–309 kg/ha of N and K, respectively) increased class 1 yield in the first harvest and reduced total discards. In 1992, a year with a colder than average spring, the low fertilizer rate (70–81 kg/ha of NK) increased class 1 yield in the first harvest. Mid‐ or late‐season fertigation produced more second harvest yield and less discards than the first harvest in 1991, but not in 1992. Fruits of plants fertilized with high N and K rates had greater N and dry matter concentration. No differences in color or wall thickness at harvest were detected among treatments. Stored fruits turned red slower with the late season low fertilizer rate. There were no differences in rate of weight loss during storage at 10°C. No differences in progression of bacterial soft rot were detected among treatments in 1991, but the higher fertigation rates or late timing application increased resistance in 1992.     

Influence of nitrogen rates and row spacing on corn yield,protein content,and other plant parameters

New maize hybrids has been intensively used as the first and second crop at the Cukurova region of Turkey in recent years. Therefore, nutritional problems of corn needs to be solved for the optimum yield, and protection from the potential insect and disease damages. Influence of nitrogen (N) and row spacing (RS) on corn yield, grain protein content, and selected plant parameters have been studied under field conditions in 1994 and 1995. Nitrogen was applied in the rates of 200, 250, 300, and 350 kg N ha^‐1 to main plots where row spacings were 10, 15, 20, and 25 cm in each subplots. Phosphorus (P) and potassium (K) were applied to each plot as basal rates. The experiment was arranged in a split‐plot design in three replications. During course of the experiment and after harvest, selected plant parameters, leaf nutrient contents, root length, grain yield, and crude protein content were measured, and the data were statistically analyzed for determination of treatment effects. The selected plant parameters either influenced by N, RS, or both in 1994 and 1995. The leaf N content was affected by N and RS in 1995, and a RS effect was only observed in 1994. Grain yield was influenced by RS and N and RS in the first and second years, respectively. Grain yield ranged between 7.3 to 12.8 Mg ha"¹ for both years. Treat ment effects on crude protein content was significant in 1994 but no response was obtained in 1995.     

Effects of fertilizer rate,application timing and plant spacing on yield and nutrient content of bell pepper

Bell pepper (Capsicum annuum var annuum L.), cv Pip, transplants were established at 31 and 46 cm in‐rows on bare soil and drip irrigated on a twice weekly schedule. A base rate of fertilizer was applied either in one preplant application or in two (preplant and first flower set) or three (preplant, first flower set, after the midseason harvest) split applications. Additional fertilizer was applied in excess of the base rate on a predetermined schedule or after significant yield decline ('as needed'). Concentrations of 12 elements in leaf and fruit tissues were determined throughout the growing season. The three‐split application of the base rate of fertilizer increased total yield. Plants spaced at 46 cm had increased total and marketable yield in one year. Interactions of fertilizer treatment and plant spacing did not affect total yield. In one year when additional fertilizer was applied ‘as needed’, plants spaced at 31 cm produced more marketable yield than plants spaced at 46 cm. Nutrients in leaves and fruit did not respond to fertilizer treatment or spacing. In leaves and fruit, concentrations of elements increased, decreased/or stayed the same in both years. For leaves, exceptions were Cu, Mn, and N. For fruit, exceptions were Al, Fe, K, and N. A base level application of fertilizer applied preplant was sufficient to support marketable fruit production.     

钾肥分期施用对苏丹草生长和产量的影响

在大田条件下研究了KCl分期施用对苏丹草产量及生长性状的影响。结果表明,基肥施用一定量KCl对基本苗数量影响不大,过量施用KCl则对苏丹草基本苗产生抑制作用。施钾没有导致苏丹草叶片质量比例下降。施用KCl明显提高苏丹草对蚜虫的抵抗能力,5个施钾处理所寄生的蚜虫数量平均为不施钾的27.2%。施用KCl显著增加苏丹草鲜草产量和经济效益,在钾肥用量相同时,不同施钾时期及钾肥用量分配对产量产生显著影响。在5个施钾处理中,以50%作基肥、在第2、3和4次收获后平均施用余下50%钾肥的增产效果最好,比对照增产16615kg/hm2,增产幅度达26.1%,每千克K2O增收苏丹草46.2kg;而KCl一次性作基肥施用增产效果较差。     

Mulberry nutrient management for silk production in Hubei Province of China

The silk industry is important for south China's rural economy. Leaves of mulberry (Morus spp.) are used for silkworm production. Hubei province is one of the main silk‐producing provinces in China. The objectives of this research were to survey the fertilization practices in the mulberry‐producing regions in the province and to determine the best nutrition‐management practice for mulberry plantations. A survey and a series of field experiments with N, P, K, and micronutrients were conducted from 2001 to 2002. In addition, a silkworm‐growth experiment was also conducted by feeding leaves harvested from various fertilization treatments. The results indicate that poor soil fertility and unbalanced fertilization were the main factors limiting mulberry‐leaf yield and quality in Hubei province. Nitrogen fertilization of mulberry has reached a high level (454 kg ha^–1 y^–1) in Hubei province, but P‐ and K‐fertilization rates have not been matched with N‐fertilization rates as farmers are not aware of the significance of P and K. Balanced fertilization showed positive nutrient interactions with respect to mulberry yield and quality. Potassium application increased yield and quality (protein and sugar concentration) of mulberry leaves. Silkworm growth and cocoon quality were improved when silkworms were fed with the leaves derived from K‐fertilized plants in comparison with those taken from control plots. Application of Mg, S, and B also significantly improved leaf sugar, essential and total amino acid concentrations, but did not increase leaf yield significantly. It is concluded that a fertilizer dose of 375 kg N ha^–1, 66 kg P ha^–1, and 125 kg K ha^–1 is suitable for the cultivation of mulberry in the Hubei province along with Mg, S, and B, wherever necessary, for the improvement of yield and quality of mulberry leaves.     

Influence of surfactants on potassium uptake and yield response of cotton to foliar potassium nitrate

Foliar potassium (K) applications are intended to supplement soil K uptake, and thereby, increase cotton (Gossypium hirsutum L.) yields. Considerable research has been conducted to evaluate yield response to foliar K, but research evaluating surfactant effects on foliar uptake has been limited. Research was initiated in West Tennessee in 1991 to evaluate effects of foliar applied potassium nitrate (KNO₃) with and without surfactants on leaf and petiole K concentrations and on lint yield. Field research was conducted on three sites over a four year period using upland cotton ‘DPL 50’. Treatments included a check (no foliar treatment), 4.1 kg K/ha in water, 4.1 kg K/ha with Penetrator Plus, 4.1 kg K/ha with X‐77, 2.0 kg K/ha with Penetrator Plus, and 2.0 kg K/ha with X‐77. Surfactants were added to KNO₃ solutions at 1.25% v/v for Penetrator Plus and 0.5% v/v for X‐77. Kinetic was substituted for X‐77 after 1991 and was applied at 0.12% v/v. Cotton leaves and petioles were collected one, three, and seven days after each foliar application for K concentration determinations. Applying 4.1 kg K/ha (high‐K rate) as KNO₃ in water increased four‐year average leaf K but not petiole K concentrations in tissue collected 24 h after treatment relative to the check. Applying the high‐K rate with a surfactant increased the four‐year average concentration of leaves and petioles collected one, three, and seven days after application relative to the check or to the high‐K rate applied with water. Increases in both leaf and petiole K concentrations varied with year, with significant increases in two of the four years of the study. Yearly K concentrations of the day‐one and day‐three petioles were higher after applying the high‐K rate with Penetrator Plus relative to the check. Petiole K was not increased by applying low‐K rates with surfactants or the high‐K rate in water. First harvest lint yields were generally unaffected by foliar treatments. Second harvest and total yields were increased by applying the high‐K rate with Penetrator Plus relative to the other treatments. Yield responses may have been due in part to the nitrate anion (NO₃‐) being applied with the K+ cation, but higher K concentrations generally accompanied higher yields. These results suggest that surfactants may enhance K uptake and yield, but that more research is needed to determine why responses vary from year to year.     

Dry matter production,nutrient uptake,and growth of cotton as affected by potassium fertilization

Insufficient potassium (K) nutrition produces detrimental effects on cotton (Gossypium hirsutum L.) lint yield and fiber quality. To further understand the deleterious effects caused by K deficiency, a 2‐yr (1991 and 1992) field study was conducted to determine how dry matter partitioning and nutrient concentrations of various plant tissues for the cotton genotypes, ‘DES 119’ and ‘MD 51 ne’, were altered by varying the application rate of fertilizer K and nitrogen (N). All plots received a preplant application of 112 kg N ha^‐1, and half of the plots were later sidedressed with an additional 38 kg N ha^‐1. Within each N treatment, half the plots received 112 kg K ha^‐1, preplant incorporated, with the remaining plots not receiving any fertilizer K. Dry matter harvests were taken three times in 1991 and two times in 1992. At cutout (slowing of vegetative growth and flowering), plants that received K fertilization had a 14% more leaf area index (LAI), a 3% increase in the number of main stem nodes, and a 2% increase in plant height. However, those plants had a 12% lower specific leaf weight (SLW) than plants receiving no K fertilization. By the end of season, the of K fertilization had resulted in more stem (21%), bur (13%), seed (19%), and lint weight (20%), but harvest index was not affected. Varying the level of N fertilization did not affect any of these dry matter parameters at any harvest. In general, the larger plants produced under K fertilization had reduced concentrations of N, phosphorus (P), magnesium (Mg), and sodium (Na) in the various plant parts. While N uptake efficiency was not affected by K fertility, plants that received K fertilization had increased efficiency of fertilizer N use and of N utilization within the plant. The smaller LAI of the K deficient plants probably reduced the photosynthetic capacity per plant. A reduced assimilation capacity could explain the inefficiency of N use, lint yield reductions, and poorer fiber quality often associated with K deficiencies.     

The effect of potassium soil amendments,trenching and foliar sprays on the mineral content,growth, yield and fruit quality of sweet cherry (Prunus avium L.) and prune (Prunus domestica L.)

Abstract

Potassium sulfate was applied to established, non‐irrigated, K deficient trees on fine textured soil by banding, placing in augered holes and injecting into the soil. Additional trees received a heavy compost mulch in early fall. Trenches were dug in the fall beside trees to break roots and then were backfilled with K₂SO₄, dolomite lime or a combination of the two. One percent K solutions of KNO₃ or K₂SO₄ were sprayed on trees four times during the growth season.

Sweet cherry trees only responded to compost mulch applications within two years. August midshoot leaf K, leaf N and fruit size were increased within one year however tree growth and yield were not affected. Fruit size and shoot growth were partially dependent on August leaf K level.

August midshoot leaf K of prune trees was increased within one growing season by all treatments except trench plus lime. Trees receiving compost also had increased levels of leaf N, P, Ca, Mn, Fe, Cu and B. Yield and shoot growth were increased only by compost mulch applications. Fruit size was partially dependent on August leaf K levels.     

Potassium uptake by soybean as affected by exchangeable potassium in soil

Abstract

Soybean (Glycine max (L.) Merrill) has been shown to have a great capacity to take K from soil, suggesting that it might absorb K from non‐exchangeable forms. In this paper, the effect of level of K fertilization on soil exchangeable K content and K uptake by soybean are discussed. The experiment was conducted on a Typic Haplortox (sandy loam), fertilized with 0, 40, 80, 160 and 240 kg K₂O/ha as KC1 or K₂SO₄. During five years before the experiment, half of the plots received those K rates annually and the other half only in the first three years, providing an opportunity to study the residual effect of applied K. Plant samples were taken at pod filling and at harvest. Soil cores were collected in 20 cm increments down to 80 cm deep at plant emergence, pod filling and after harvest. There was a residual effect of K, and 240 kg K₂O/ha applied in a 3‐year term led to the same yield and K uptake as 80 kg ICO/ha applied annually for 3 years. Fertilized plants absorbed 160% more K than unfertilized ones, but soil exchangeable K accounted for less than 50% of plant uptake; therefore the exchangeable pool must have been replaced in time for soybean uptake. On the other hand, the K recycled from the plant to the soil was not found in the exchangeable form. There was evidence of K leaching deeper than 80 cm, and in addition, the K recycled from the plants may have turned into non‐exchangeable forms in the soil.     

The DRIS for interpretation of coastal bermudagrass analysis

Abstract

Diagnosis and Recommendation Integrated System (DRIS) norms for N, P, K, Ca, Mg, and S were developed for three high‐yield Coastal bennudagrass populations that were selected from soil fertility studies that contained six rates each of N, P, and K. Norms from the high‐yield population that was based on a single yield level at a given harvest date were considered most suitable. The relative importance of criteria used to select suitable diagnostic parameters was discussed along with composition of index equations. The norms developed from Coastal bennudagrass grown on an Aquic Fragiudalf soil in south Louisiana accurately predicted yield responses to N, P and K applications at that location and to P, S, and Mg applications on Typic Paleudult soils in north Louisiana. A computer generated DRIS balance chart was designed to provide a visual interpretation of individual sets of DRIS indices.     

Effect of potash fertilizer on leaf nutrients and their relationships to tuber yields of sweet potato

Abstract

The fourth, fully‐expanded leaves at sweet potato vine tips were sampled at harvest from two separate but similar experiments on njala upland soils after 7 years bush fallow to study the effects of timing and rates of K fertilizers on leaf nutrients and their relationships to sweet potato tuber yields. Potash showed significant effects on leaf P, leaf Zn, leaf Ca, leaf Mn, leaf K/P and leaf Ca/Mg. K x timing interaction affected leaf K/Mg and leaf K/P but timing of Z application did affect significantly neither leaf nutrients nor leaf nutrient ratios. Significant quadratic effect of K on tuber yields as well as significant cubic K x timing interaction effect on tuber yields were observed. There were significant negative correlations between tuber yields and leaf N and between tuber yields and leaf P, indicating that increases in either leaf N or leaf P depressed yields. On the basis of coefficient of determination, increases in leaf N contributed significantly more to yield variation than increases in leaf P. Analysis of covariance and multiple regression studies showed lack of significance of 10 nutrients on tuber yields. Sweet potato tissue which reflects differential nutrient levels with significant effect on tuber yields must be sought. Apart from the added fertilizer, the total effect of ether factors which affect nutrient status and crop performance must be considered.     

Effects of nitrogen carriers,nitrogen rates,and maturity on composition of smooth bromegrass

Abstract

Magnesium and Ca concentrations in smooth bromegrass (Bromus inermis L) were not affected by late‐winter applications of N. Magnesium concentrations were constant until rapid growth in mid‐May then they declined until early June harvest. Highest seasonal concentrations were found in the fall regrowth. Calcium concentrations declined as plants matured in spring. Highest seasonal Ca concentrations were found in the fall regrowth. Nitrogen, P, and K concentrations and K/(Ca+Mg) ratios were increased by N applications during early spring but did not differ significantly by early June harvest. Nitrogen and P concentrations decreased as plants matured in spring and fall. K concentrations and K/(Ca+Mg) ratios changed inconsistently from sampling date to sampling date. Forage yields were approximately doubled by 67 kg N/ha and tripled by 202 kg N/ha. Significant yield differences were related to different N carriers.     

Effect of fertilization and irrigation upon NPK composition of corn leaves,on corn yields,and available k in soil

Abstract

Corn (Zea mays L.) was grown for three consecutive years on Congaree loam to measure the effects of rates of N, P, and K fertilization and irrigation on the nutrient concentration of leaves, the level of available K in the soil, and on the yield of corn. Plant nutrients consisting of 0, 56, 140, 224, and 280 kg N/ha; 0, 15, 37.5, 60, and 75 kg P/ha, and 0, 28, 70, 112, and 140 kg K/ha were applied in a central composite rotatable design in each of the three years. All plant residue was removed each year when the corn was harvested, and the plots remained fallow during the winter months. One half of the experiment was irrigated when there was a 50% depletion of available soil moisture in the 0‐ to 46‐cm soil depth.

Leaf composition was affected by fertilization and irrigation. A rapid decrease in available soil K in the 0‐ to 15‐cm depth was evident the first year with all rates of added K. The decline in available soil K was unaffected by irrigation and levels of applied N and P.

There were consistent yield responses each year to added N, no response to added P, and a response to added K only during the second year.     

Effects of wastewater irrigation on soil and cabbage‐plant (brassica olerecea var. capitate cv. yalova‐1) chemical properties

The use of wastewater for irrigation is increasingly being considered as a technical solution to minimize soil degradation and to restore nutrient contents of soils. The aim of this study is to increase fertility and minimize degradation of soils irrigated with wastewater exposed to different purification treatments. A field experiment was conducted to investigate the effects of control and irrigation with wastewater, which had undergone different purification treatments, on macro‐ and micronutrient distribution within the soil profile and nutrient contents of cabbage (Brassica olerecea var. Capitate cv. Yalova‐1) in Erzurum, Turkey. Wastewater irrigation and preliminary treatment–wastewater irrigation significantly affected soil chemical properties especially at 0–30 cm soil depth and plant nutrient contents after one year. Application of wastewater increased soil salinity, organic matter, exchangeable Na, K, Ca, Mg, plant‐available P, and micro‐elements and decreased soil pH. Wastewater increased also yield and N, P, K, Fe, Mn, Zn, Cu, B, and Mo contents of cabbage plants. Undesirable side effects were not observed in plant heavy‐metal contents, due to salinity and toxic concentrations of metals from the application of wastewater to soil.     

中文参考篇名: 发育于第四纪红壤的某新垦红壤旱地的肥力特征与肥料需求

A series of field experiments from 1990 to 1994 in Yingtan, Jiangxi Province, were conducted on an upland red soil derived from Quaternary red clay which had been reclaimed three years before the experiments, in order to study the fertility characteristics and fertilizer requirements of the newly reclaimed soil. The field experiments included that on nutrient characteristics and fertilizer effect, that on K-supplying potential and K-Mg relationship, that on fertilization rates of K and N, etc. The newly reclaimed upland soil was low in both N and P, and its responses to nitrogen and phosphate application were very significant. The K-supplying potential was also low, so the soil was highly responsive to K fertilizer. The effect of Ca and Mg fertilizers was not so great for the reason that certain amounts of Ca and Mg were incorporated into the soil through application of calcium magnesium phosphate during land leveling before the experiments. Among the four micronutrients, B, Mo, Zn and Cu, B had the greatest effect on the soil. The fertilizer requirements of the soil were in an order of P and N > K > lime and B > Mg > Mo, Zn and Cu. Eight crops tested had different fertilizer-requiring characteristics. Rapeseed was very sensitive to P and B fertilizers. Barely was especially sensitive to P and lime and it also responded to B, Mo, Zn and Cu. And sweet potato was especially sensitive to K.     

不同施钾方式对甘薯钾素吸收及产量的影响

【目的】钾素是调控块根类作物生长和产量的关键因子,特别是对淀粉型甘薯后期块根膨大及产量形成尤为重要。本试验选择胶州(砂姜黑土)和即墨(风沙土)两个不同土壤质地类型的试验点布置田间试验,探究不同施钾方式在两种不同类型土壤条件下对甘薯钾素吸收、 钾肥利用率以及产量形成的影响,以期对甘薯生产提供理论指导。【方法】借助水肥一体化技术能够实现甘薯钾营养的精细化调控,提高钾肥利用率和促进甘薯生长。试验共设置4个处理: K0(不施钾肥,CK)、 K1(钾肥基施)、 K2(钾肥1/2基施+1/2封垄期追施)和K3(钾肥全部封垄期追施)。【结果】与CK相比,三种不同施钾方式均显著提高了甘薯生物量、 养分吸收量及产量(P0.05)。与K3和 K1处理相比,砂姜黑土条件下K2分别增产18.7%和10.4%,但K3和 K1处理之间的产量差异不显著; 风沙土条件下K2增产幅度分别为35.3%和17.3%,其中K1处理的产量显著高于 K3处理(P0.05)。与K1处理相比,K2处理显著提高了甘薯生长中后期(115天~150天)钾素积累量和地下部生长速率,同时提高了钾收获指数、 钾肥偏生产力、 钾效率、 钾肥农学利用率。与K1 和K3相比,砂姜黑土条件下K2处理的钾肥表观利用率分别提高了12.5%和8.8%,风沙土条件下K2处理的钾肥表观利用率分别提高了13.9%和13.2%。不同土壤类型条件下同一施钾方式相比较,砂姜黑土条件下氮钾积累量、 生物量和产量均高于风沙土,但K2处理的钾素日积累速率、 钾素利用率与增产效应均表现为风沙土高于砂姜黑土。【结论】在供钾量较低的风沙土上采用分期施钾(1/2基施+1/2封垄期追施)能显著提高钾肥利用率和增加甘薯产量,是甘薯合适的施钾方式。     

不同供氮水平对夏玉米养分累积、转运及产量的影响

通过田间小区试验,研究了高肥力土壤上施N.125、250、375.kg/hm2对夏玉米生物量、子粒产量、N、P、K养分累积动态、及氮肥表观利用率、养分转运的影响。结果表明,不同施氮量只影响夏玉米不同生育时期养分的阶段累积量,而对累积趋势基本无影响。植株生物量及N、P、K养分累积量随生育期的延长而增加,且它们的累积趋势相似,都呈S型曲线。各处理的子粒产量在7000～7700.kg/hm2之间,只有N250处理增产达显著水平;氮肥表观利用率在10%～18%之间,随施氮量的增加略有降低。施氮可提高子粒中的氮素累积量,而对磷的累积量影响不大。随着施氮量的增加,氮素的转运量、转运效率及其在子粒中的比例都降低,磷的转运与氮表现出类似的趋势。综合考虑产量、氮肥利用率、养分转运及环境污染等因素,该地区夏玉米的推荐施氮量应控制在125.kg/hm2以内。     

Assessment of economic and environmental impacts of two typical cotton genotypes with contrasting potassium efficiency

It is essential to produce optimal crop yields while reducing adverse environmental impacts of overfertilization. Therefore, nutrient‐efficient plants may play a major role in improving the efficiency of fertilizer use whilst increasing crop yields. This field trial was conducted to study the differences on absorption and utilization of nitrogen (N), phosphorus (P), and potassium (K) of K‐efficient cotton genotype 103 and K‐inefficient cotton (Gossypium hirsutum L.) genotype 122 and their environmental and economic effects. The results show that seed cotton yield was significantly different between K‐efficient cotton genotype 103 and K‐inefficient cotton genotype 122; the yields of genotype 103 were 39.2%, 33.8%, and 25.0% higher than those of genotype 122 with no K fertilizer (K0), 112 kg K ha^–1 K (K1), and 224 kg K ha^–1 (K2), respectively. Even when no K fertilizer was applied, the yield of genotype 103 was still 7.9% higher than the yield of genotype 122 at the highest K level (K2). Further economic benefit analysis revealed that the value cost ratio (VCR) of genotype 103 was significantly higher than 122 at K0 and K1, and harvest index (HI) of genotype 103 was significantly higher than that of genotype 122 at all three K levels. In addition, when fertilized with K, partial factor productivity of applied K (PFP_K) of genotype 103 was dramatically higher than that of genotype 122, demonstrating that genotype 103 had stronger ability to utilize K. Besides, the N‐ and P‐use efficiencies of genotype 103 were also higher than those of genotype 122. It is concluded that: (1) genotype 103 gives better profit than genotype 122 and (2) genotype 103 uses fertilizer more efficiently and reduced fertilizer inputs will alleviate environmental risks.     

施用氮钾肥对设施蔬菜产量和品质影响的研究

The application of large amounts of fertilizers, a conventional practice in northern China for the production of vegetable crops, generally leads to substantial accumulation of soil nutrients within a relatively short period of time. A fixed field experiment was designed to study the effects of nitrogen （N） and potassium （K） fertilizers applied to optimize the yield and quality of typical vegetable crops. Application of N and K fertilizers significantly increased the yields of kidney bean. The largest yields were obtained in the first and second years after application of 1 500 kg N and 300 kg K20 ha^-1. In the third year, however, there was a general decline in yields. Maximum yields occurred when intermediate rates of N and K （750 kg N and 300 kg K20 ha 1） were applied. However, no significant differences were observed in the concentrations of vitamin C （VC） in kidney bean among different years and various rates of fertilizer treatments. Yields of tomato grown in rotation after kidney bean showed significant responses to the application of N and K in the first year. In the second year, the yields of tomato were much lower. This suggested that the application of N fertilizer did not have any effect upon tomato yield, whereas application of K fertilizer did increase the yield. Application of K fertilizer was often associated with increased sugar concentrations.