磷素水平对大豆氮素积累及产量的影响

利用砂培方法和15N示踪技术研究了磷素水平对大豆氮素积累、根瘤固氮和产量的影响。结果表明:大豆植株氮素积累、根瘤固氮和产量均随磷素营养水平的提高而呈单峰曲线变化,营养液磷素浓度31mg/L左右时达到峰值,当营养液磷素浓度达11mg/L时,再提高磷素浓度对大豆根瘤固氮率无明显促进作用;而对于大豆植株氮素积累、根瘤固氮量和产量,只有当营养液磷素浓度达到21mg/L时,再提高磷素浓度才无明显促进所用,表明满足根瘤固氮的磷素营养水平较产量形成的水平要求低。     

氮肥用量及施用时间对土体中硝态氮移动的影响

土连续两年小麦—玉米轮作条件下 ,播前一次施氮量 130～ 5 2 0kghm-2 a-1时 ,氮肥用量对硝态氮在土体中的移动深度没有影响 ,但土壤剖面中残留的硝态氮量随施氮量增加显著增加。播前一次施用氮肥 ,差减法计算的肥料氮表观回收率 (作物携出量和土壤硝态氮的残留量 )为 6 2 %～ 82 7% ;就作物而言小麦的携出率高于玉米 ,在玉米生长季节有更多的硝态氮可能被淋移至土壤剖面的下层。小麦—玉米轮作一年 ,不同的施氮时间对肥料氮的表观回收率以及硝态氮在土壤剖面中的分布、累计没有明显影响。土区合适的氮肥用量是控制硝态氮向深层移动的主要措施     

INFLUENCE OF ORGANIC AND MINERAL FERTILIZATION ON GERMINATION,LEAF NITROGEN,NITRATE ACCUMULATION AND YIELD OF VEGETABLE AMARANTH

The influence of manure and diammonium phosphate (DAP) mineral fertilizer on germination, leaf nitrogen content, nitrate accumulation and yield of vegetable amaranth (Amaranthus hypochondriacus) was investigated. Field trials were set up at the University of Nairobi Field Station at the Upper Kabete Campus during the long rains of March–May in 2007 and 2008. Trials were laid out as complete randomized block design with four fertilization treatments: 20, 40, and 60 kg nitrogen (N) ha^?1 supplied by DAP (18:46:0), 40 kg N ha^?1 supplied by cattle manure and an unfertilized control variant. The vegetables were harvested at three maturity stages at 6, 7, and 8 weeks after planting. Results indicated that there were significant differences between treatments in germination percentage, leaf nitrogen content, nitrate accumulation and vegetable yield. Plants that received manure had a higher germination percentage than those that received the same amount of N supplied by the chemical fertilizer DAP. The yields generally increased from week 6 to week 8. The highest yield was recorded in plots receiving 40 kg N ha^?1 from DAP at eight weeks after planting. Plots that were supplied with manure recorded the lowest yield when compared to the fertilizer treated plots at all rates. Leaf nitrogen content increased with increasing rate of N but only when N was supplied by DAP fertilizer. The leaf nitrogen content decreased with increasing age of the plants. The leaf nitrate content increased with increase in DAP application rate. Results indicate that manure application produced quality vegetables in terms of low nitrate levels, but leaf nitrogen and vegetable yields were low. DAP application effected higher yields, but the vegetables had high though acceptable nitrate levels.     

氮肥对大白菜硝酸盐累积的影响及合理施用量研究

对宁夏灌淤旱耕人为土氮(N)肥与大白菜产量及菜体和土体中硝酸盐累积的关系进行了田间试验研究。结果表明,在设计范围内,银川平原复种大白菜的产量及净菜率与施N量成正比;施N肥增加大白菜硝酸盐含量;复种大白菜的最高产量施N量为448.5㎏/hm2,最佳产量施N量为427.5㎏/hm2;大白菜外叶硝酸盐含量高于内叶,内叶硝酸盐含量随施N肥量的增加而增加,外叶硝酸盐含量在高施N时,随生育期延长而增加;施用N肥明显增加土体各土层中的硝态N含量。     

NITRATE IN LEAF PETIOLE AND BLADE OF SPINACH CULTIVARS AND ITS RELATION TO BIOMASS AND WATER IN PLANTS

A pot experiment was carried out, with 30 spinach cultivars to determine nitrate accumulation in leaf blade and petiole, and its relationship to biomass and water in plants. Results showed that the fresh weight proportion of blade to shoot was higher than that of petiole. Furthermore, a higher positive correlation was found between fresh weights of blades and shoots than that of petioles and shoots. Unlike biomass, nitrate-nitrogen (N) concentration and total amount of nitrate-N accumulated in petiole were significantly higher than those in blade, and petiole was obviously the main organ for nitrate accumulation. Differences of nitrate-N concentration in petiole and the observed positive correlation between nitrate-N concentrations in petioles and shoots were more significant than that in blades and shoots. Nitrate-N concentration in petiole was also significantly correlated with fresh and dry shoot weight and total amount of water in shoots. However, this relationship was not found for blade.     

施肥水平对冬大麦干物质和氮素积累与转运的影响

为合理利用氮肥,进一步提高大麦产量和品质,以扬饲麦3号、港啤1号、扬农啤2号和Frankin共4个品种为供试材料,研究了0(CK),90(NL),180(NM)和270kg/hm2(NH)4个氮肥水平下冬大麦干物质和氮素积累、转运及对籽粒贡献的规律。结果表明,随着施氮量的提高,大麦干物质花前积累量呈增加趋势,积累率及对籽粒的贡献率呈下降趋势,各器官的转运量在NM处理(180kg/hm2)范围内呈增加趋势,高于此范围则下降。氮素营养花前积累量和转运量各品种均呈上升趋势,花前积累率、转运率和对籽粒氮的贡献率都呈下降趋势。不同品种不同氮肥处理下大麦干物质转运量以茎秆为最大,转运率大部分以芒壳+穗轴为最高,对籽粒的贡献率以茎秆为最高。各器官氮素转运量以叶片最高,转运率以芒壳+穗轴最大,氮素转运对籽粒的贡献率以叶片最高。大麦各品种籽粒产量与施氮量呈二次曲线关系,氮素积累量与施氮量呈显著线性正相关关系。表明在本试验条件下,大麦最高产量的最佳施氮范围为212.42～261.97kg/hm2。     

GROWTH AND LEAF YIELD DYNAMICS OF COOL SEASON CORIANDER AS INFLUENCED BY CUTTING AND FOLIAR NITROGEN APPLICATION

An experiment was conducted to study regrowth and yield of coriander influenced by nitrogen (N) with five different urea doses (0, 1.5, 2.0, 2.5, 3.0% by volume) as foliar spray. Spraying of urea has a significant impact on growth and yield in the second cut. Leaf emergence rate (LER) was higher during initial growth phase and then drastically reduced until first cutting, whereas the stem elongation rate (SER) recorded its peak value during 75-105 DAS. Impact of foliar spray was conspicuous during the later phase of regrowth with the treatment of 2.5% urea achieving the highest SER. Additional return due to spraying was positive up to a dose of 2.5% urea and decreased thereafter. Hence, the study indicated that a foliar spray of nitrogen (2.5% urea) may be beneficial for coriander leaf production under multicut system and the crop is sensitive to rainfall, phototemperature, and morning humidity.     

施氮水平对大豆氮素积累与产量影响的研究

以绥农14为材料,利用砂培和15N标记的方法研究了施氮水平对大豆氮素积累及产量的影响。结果表明:随着施氮水平的提高,大豆全株氮素积累量及叶柄、荚皮、籽粒中氮素积累量呈现先增加后下降的趋势;高氮水平增加了叶片和茎中氮素积累量,N150较N0处理叶片的氮素积累量增加了3倍,而茎增加了5倍,但减少了根中氮素积累,降低了大豆全株和籽粒中根瘤固氮量及其所占比例,降低了肥料氮和根瘤氮的收获指数,其中根中氮素积累N150较N50处理降低了60.3%,全株根瘤氮和籽粒中根瘤氮N150较N0分别降低了74.9%、85.7%,肥料氮的收获指数N150较N50降低19.8%,根瘤氮的收获指数N150较N0降低25.5%。随着施氮水平的增加,大豆产量也呈现先增加后下降的趋势,施氮水平的增加促进了大豆植株株高、结荚高度和始荚节位的显著增加,但对节数没有明显影响,N150和N0比较株高增加了55.2%,结荚高度增加了199.7%,始荚节位增加了142.9%。     

氮素水平对不同氮效率基因型水稻的物质生产与分配的影响

研究了在群体水培条件下,3种氮素水平(5、15和25mg.kg-1)对6种不同氮效率利用基因型迟熟中粳水稻物质生产与分配的影响。结果表明:氮素水平、基因型对水稻氮素干物质生产效率(NUEdm)、氮素籽粒生产效率(NUEg)均有极显著的影响。6种不同氮效率基因型可分成氮高效和氮低效利用型2类。NUEdm在2类基因型水稻中总体上均随着氮素水平升高呈现上升趋势;而NUEg在氮低效基因型中表现为随氮素浓度升高而先升后降。在水稻的4个关键生育期,不同氮素水平、2类基因型之间水稻干物质积累量差异显著。成熟期,氮素水平对水稻茎鞘、根、穗的干物质分配比例影响显著,对叶片干物质分配比例影响不显著。相同氮素水平下,就平均值而言,水稻茎鞘、叶片、根系干物质比例均表现为氮低效基因型>氮高效基因型,而穗的干物质比例均表现为氮高效基因型>氮低效基因型。氮素水平对不同基因型水稻产量影响显著,同一氮素水平下均表现为氮高效型基因型水稻产量显著高于氮低效型基因型,且施氮量越大差异越大。相关分析表明,水稻各关键生育期的干物质生产量、产量、每穗粒数均与氮素水平、基因型的NUEg、NUEdm显著或极显著相关,与成熟期水稻各器官干物质分配比例相关性则相对较弱。     

DAIRY MANURE AND NITROGEN FERTILIZER EFFECTS ON RESIDUAL NITRATE AND PHOSPHATE,AND WHEAT YIELD IN A SANDY CLAY LOAM SOIL

Dairy manure (DM) rates of [0 (DM₀), 30 (DM₃₀₎), 60 (DM₆₀) Mg ha^?1] and three nitrogen (N) rates [0 (N₀), 125 (N₁₂₅), 250 (N₂₅₀) kg ha^?1] were tested in a sandy clay loam, to evaluate their effects on growth and yield of wheat crop (Triticum aestivum L.), residual nitrate nitrogen (NO₃-N) and phosphorus (P) concentrations in the surface soil, and selected soil physical measurements [saturated hydraulic conductivity (Ksat), and bulk density (BD)]. Increasing N and DM rates gave higher wheat yields, increased concentrations of residual NO₃-N and P in the surface soil and improved Ksat and BD. Highest grain yield of 3.8 Mg ha^?1 (70.3% more than the control) was observed in DM₆₀ × N₂₅₀ treatment. Residual accumulation of N-NO₃ and P in the surface soil at high N and/or DM application rates suggests the need to carefully manage N and DM inputs on farm fields to avoid environmental contamination.     

YIELD AND YIELD COMPONENTS OF UPLAND RICE AS INFLUENCED BY NITROGEN SOURCES

Ammonium sulfate and urea are main sources of nitrogen (N) for annual crop production in developing countries. Two greenhouse experiments were conducted using ammonium sulfate and urea as N sources for upland rice grown on a Brazilian Oxisol. The N rates used were 0, 50, 100, 150, 3000, and 400 kg N kg^?1 of soil. Yield and yield components were significantly increased in a quadratic fashion with increasing N rate. Ammonium sulfate X urea interaction was significant for grain yield, shoot dry matter yield, panicle number, plant height and root dry weight, indicating a different response magnitude of these plant parameters to two sources of N. Based on regression equation, maximum grain yield was achieved with the application of 380 mg N kg^?1 by ammonium sulfate and 271 mg N kg^?1 by urea. Grain yield and yield components were reduced at higher rates of urea (>300 mg kg N) but these plant parameters’ responses to ammonium sulfate at higher rates was constant. In the intermediate N rate range (125 to 275 mg kg^?1), urea was slightly better compared to ammonium sulfate for grain yield. Grain yield was significantly related with plant height, shoot dry weight, panicle number, grain harvest index and root dry weight. Hence, improving these plant characteristics by using appropriate soil and plant management practices can improve upland rice yield.     

ZEOLITE AS SLOW RELEASE FERTILIZER ON SPINACH YIELDS AND QUALITY IN A GREENHOUSE TEST

There has been a great need to reduce the non-point source pollution due to pesticide and fertilizer applications. With a high surface area and large cation exchange capacity, zeolite was proposed to use as carriers to control ammonium and potassium release. A greenhouse test was conducted to evaluate spinach growth and spinach quality after application of zeolite pre-load with ammonium (NH₄ ⁺) and potassium (Eco-zeolite). An increase in spinach yield with comparable vitamin C content was achieved using the Eco-zeolite. However, elevated oxalate content was unexpected, possible due to the presence of NH₄ ⁺ as the exchangeable cations after modification.     

STABILITY OF FOLIAR NITROGEN:SULFUR RATIO IN SPRING RED WHEAT AND SULFUR DILUTION CURVE

A key aspect of any sulfur (S) availability indicator is its stability throughout the crop cycle. Nine experiments were conducted with the objective to evaluate the stability of the nitrogen (N):S ratio in aerial biomass (W) in spring wheat, and to define the critical curve of S dilution. As the crop cycle progressed, a decrease (P < 0.05) in total N:S was determined. This lack of stability was explained by a lower S dilution in relation to N (P < 0.05). A decrease (P < 0.05) in N accumulation rate in relation to S was obtained as the crop cycle progressed, which points out that S accumulation in relation to N is later. A first approach was determined to the definition of the S dilution critical curve (Sc) from tillering beginning to stem elongation end (Sc = 0.37 W^?0.169; r² = 0.71 and n = 24).     

大豆硝酸还原酶活性及其与施氮关系的研究

以绥农14为材料,利用框栽、砂培和15 N标记的方法,研究了大豆硝酸还原酶（NR）活性及其与施氮水平的关系。结果表明：框栽试验中大豆叶片NR活性随生育进程的推进大体上呈单峰曲线变化,营养生长阶段叶片NR活性较低,进入生殖生长期后逐渐升高,并于盛花期前后达到峰值,随后呈逐渐下降趋势;施氮水平对NR活性有明显影响,营养生长...     

WHEAT YIELD AND PHOSPHORUS FERTILIZER EFFICIENCY AS INFLUENCED BY PRE-INCUBATED USE OF SINGLE SUPERPHOSPHATE AND POULTRY LITTER AND ITS TIME OF APPLICATION

In an effort to improve phosphorus (P) fertilizer efficiency on alkaline calcareous soils, the effect of period of pre-incubation of single superphosphate along with poultry litter and its time of application on phosphorous efficiency and yield of wheat was studied in a net house pot experiment. The results showed that application of 3–21 days pre-incubated single super phosphate + poultry litter resulted in higher phosphorous fertilizer efficiency and produced significantly higher dry matter yield of wheat at vegetative stage of growth. At maturity, however, maximum grain yield and highest phosphorous fertilizer efficiency was recorded for seven-days pre-incubation treatment only as compared to the recommended method of single super phosphate alone application at sowing. Application of pre-incubated single super phosphate + poultry litter at first irrigation also produced grain yield equivalent to single super phosphate applied alone at sowing. Under field conditions, top-dressing pre-incubated 22 and 44 kg phosphorous (as single super phosphate) along with 1 ton of poultry litter ha^?1 at first irrigation improved phosphorous uptake by 16.4 and 18.7%, phosphorous fertilizer efficiency by 65 and 58% and the grain yield of wheat by 13.4 and 12.5%, respectively as compared to phosphorous alone application at the same time.     

APPLICATION OF INCREASING LEVELS OF ZINC TO SOIL REDUCED ACCUMULATION OF CADMIUM IN LUPIN GRAIN

Yellow lupin (Lupinus luteus L.) and narrow-leafed lupin (L. angustifolius L.) are grown as grain legumes in rotation with spring wheat (Triticum aestivum L.) on acidic sandy soils of south-western Australia. Yellow lupin can accumulate significantly larger cadmium (Cd) concentrations in grain than narrow-leafed lupin. A glasshouse experiment was undertaken to test whether adding increasing zinc (Zn) levels to soil increased Zn uptake by yellow lupin reducing accumulation of Cd in yellow lupin grain. Two cultivars of yellow lupin (cv. ‘Motiv’ and ‘Teo’) and 1 cultivar of narrow-leafed lupin (cv. ‘Gungurru’) were used. The soil was Zn deficient for grain production of both yellow and narrow-leafed lupin, but had low levels of native soil Cd (total Cd <0.05 mg kg^?1) so 1.6 mg Cd pot^?1, as a solution of cadmium chloride (CdCl₂·H₂O), was added and mixed through the soil. Eight Zn levels (0–3.2 mg Zn pot^?1), as solutions of zinc sulfate (ZnSO₄·7H₂O), were added and evenly mixed through the soil. Yellow lupin accumulated 0.16 mg Cd kg^?1 in grain when no Zn was applied, which decreased as increasing Zn levels were applied to soil, with ～0.06 mg Cd kg^?1 in grain when the largest level of Zn (3.2 mg Zn pot^?1) was applied. Low Cd concentrations (<0.016 mg Cd kg^?1) were measured in narrow-leafed lupin grain regardless of the Zn treatment. When no Zn was applied, yellow lupin produced ～2.3 times more grain than narrow-leafed lupin, indicating yellow lupin was better at acquiring and using indigenous Zn from soil for grain production. Yellow lupin required about half as much applied Zn as narrow-leafed lupin to produce 90% of the maximum grain yield, ～0.8 mg pot^?1 Zn compared with ～1.5 mg Zn pot^?1. Zn concentration in whole shoots of young plants (eight leaf growth stage) related to 90% of the maximum grain yield (critical prognostic concentration) was (mg Zn kg^?1) 25 for both yellow lupin cultivars and 19 for the narrow-leafed lupin cultivar. Critical Zn concentration in grain related to 90% of maximum grain yield was (mg Zn kg^?1) 24 for both yellow lupin cultivars compared with 20 for the narrow-leafed lupin cultivar.     

VARIABILITY OF GRAIN AND OIL YIELD IN SPRING SAFFLOWER AS AFFECTED BY NITROGEN APPLICATION

This research was carried out to determine the effects of rate and time of nitrogen (N) application on safflower in a calcareous soil. The nitrogen rates were 50, 75, 100, 125, and 150 kg ha^?1 and three split application methods were used. Experimental treatments were conducted as a factorial in a randomized complete block design (RCBD) with three replications. Duncan's Multiple Range Test (DMRT) indicated that the three split application of 100 kg ha^?1 of nitrogen in stages of sowing date, early stem elongation, and early flowering had higher grain yield (2627 kg ha^?1) than other treatments. This result was forecasted by results of increases in number of heads per square meter (heads m^?2), number of grains per head (grains/head), and thousand grain weight (TGW). The highest oil yield was 755 kg ha^?1 with the 100 kg ha^?1 nitrogen application and was 727 kg ha^?1 in treatment of three split application.     

施氮量对间作玉米土壤硝态氮累积量及氮肥利用率的影响

通过田间定位试验,监测了不施氮和不同施氮水平(分别为210、420和630kg.hm-2)下间作玉米各关键生育时期0～200cm土层硝态氮累积量的动态变化、玉米产量及其构成,计算分析了间作玉米的氮肥利用率。研究结果表明,间作玉米0～200cm土层土壤硝态氮累积量总体表现为0～60cm土层>60～200cm土层。0～60cm土层土壤硝态氮累积量呈"M"形变化,即玉米播种前和玉米大喇叭口期出现高峰,小麦播种前、玉米拔节期和玉米收获后出现低谷。60～120cm和120～200cm土层土壤硝态氮累积量呈倒"V"形变化,总体在玉米大喇叭口期前后出现高峰值,210～630kg.hm-2施氮处理下120～200cm土层的硝态氮累积量较不施氮处理分别高出149.1%、115.6%和126.3%。随着施氮量的增加,间作玉米穗长、穗粒数、穗重呈增大趋势,秃顶呈降低趋势,增产幅度依次减小,氮肥利用率依次降低。