Yield and Yield Components of Dry Bean Genotypes as Influenced by Phosphorus Fertilization

Dry bean is an important legume for South American population, and phosphorus (P) deficiency is the most yield-limiting nutrient for crop production in South American soils. A greenhouse experiment was conducted with the objective of evaluating influence of P fertilization on grain yield and yield components of 30 dry bean genotypes. The P levels used were 0 mg P kg^?1 (natural level of the soil) and 200 mg P kg^?1 applied with triple superphosphate fertilizer. Yield and yield components were significantly influenced with P as well as genotype treatments. The P?×?genotype interactions were significant for yield as well as yield components, indicating different responses of genotypes at two P levels. Root dry weight and maximum root length were also significantly increased with the addition of P fertilization. There were also significant differences among the genotypes in the growth of root system. Based on grain yield efficiency index (GYEI), genotypes were classified as P efficient, moderately efficient, and inefficient. Among 30 genotypes, 17 were classified as efficient, 12 were classified as moderately efficient, and 1 was classified as inefficient. Yield components such as pods per plant and seeds per pod were having significant positive association with grain yield. In addition, grain harvest index (GHI) was also having significant linear association with grain yield. Hence, it is possible to improve grain yield of dry bean in Brazilian Oxisol with the addition of adequate rate of P fertilization as well as use of P-efficient genotypes.     

Growth of Tropical Legume Cover Crops as Influenced by Nitrogen Fertilization and Rhizobia

Tropical legume cover crops are important components in cropping systems because of their role in improving soil quality. Information is limited on the influence of nitrogen (N) fertilization on growth of tropical legume cover crops grown on Oxisols. A greenhouse experiment was conducted to evaluate the influence of N fertilization with or without rhizobial inoculation on growth and shoot efficiency index of 10 important tropical cover crops. Nitrogen treatment were (i) 0 mg N kg^?1 (control or N₀), (ii) 0 mg N kg^?1 + inoculation with Bradyrhizobial strains (N₁), (iii) 100 mg N kg^?1 + inoculation with Bradyrhizobial strains (N₂), and (iv) 200 mg N kg^?1 of soil (N₃). The N?×?cover crops interactions were significant for shoot dry weight, root dry weight, maximal root length, and specific root length, indicating that cover crop performance varied with varying N rates and inoculation treatments. Shoot dry weight is considered an important growth trait in cover crops and, overall, maximal shoot dry weight was produced at 100 mg N kg^?1 + inoculation treatment. Based on shoot dry-weight efficiency index, cover crops were classified as efficient, moderately efficient, and inefficient in N-use efficiency. Overall, the efficient cover crops were lablab, gray velvet bean, jack bean, and black velvet bean and inefficient cover crops were pueraria, calopo, crotalaria, smooth crotalaria, and showy crotalaria. Pigeonpea was classified as moderately efficient in producing shoot dry weight.     

Dry Matter and Yield of Lowland Rice Genotypes as Influence by Nitrogen Fertilization

ABSTRACT

Rice is a staple food for more than 50% of the world's population and nitrogen (N) is one of the most yield limiting nutrients in lowland rice ecosystems. A field experiment was conducted for two consecutive years to evaluate dry matter production and grain yield of 12 lowland rice genotypes (BRS Jaçanã, CNAi 8860, BRS Fronteira, CNAi 8879, CNAi 8880, CNAi 8886, CNAi 8885, CNAi 8569, BRSGO Guará, BRS Alvorada, BRS Jaburu, and BRS Biguá) at five N rates (0, 50, 100, 150, and 200 kg ha^{? 1}). Genotypes showed significant variation in grain yield and shoot dry weight. Genotype BRSGO Guará was highest yielding, whereas genotype BRS Jaburu was lowest yielding and the remaining genotypes were intermediate in grain yielding potential. Grain yield and shoot dry weight were having significant quadratic increase with increasing N rates in the range of 0 to 200 kg ha^{? 1}. However, 90% of the maximum yield is often considered as an economical rate, which was 120 kg for shoot dry weight and 136 kg N ha^{? 1} for grain yield. Shoot dry matter was having significant positive quadratic association with grain yield across 12 genotypes.     

Nitrogen Transformation as Influenced by Soil Microbial Nitrogen under Carbon Dioxide Enrichment Induced in Created Riparian Wetlands

Limited research has been conducted on how atmospheric carbon dioxide (CO₂) affects water and soil nitrogen (N) transformation in wetland ecosystems. A stable isotope technique is suitable for conducting a detailed investigation of mechanistic nutrient transformations. Nutrient ammonium sulfate (NH₄)₂SO₄ input in culture water under elevated CO₂ (700 μL L^?1) and ambient CO₂ (380 μL L^?1) was studied to analyze N transformations with N blanks for both water and soil. It was measured by ¹⁵N pool dilution using analytical equations in a riparian wetland during a 3-month period. Soil gross ammonium (NH₄ ⁺) mineralization and consumption rates increased significantly by 22% and 404%, Whereas those of water decreased greatly by??57% and??57% respectively in enriched CO₂. In contrast, gross nitrate (NO₃ ^?) consumption and nitrification rates of soil decreased by??11% and??14% and those of water increased by 29% and 27% respectively in enrichment CO₂. These may be due to the extremely high soil microbial biomass nitrogen (MBN), which increased by 94% in elevated soil. The results can show when CO₂ concentrations are going to rise in the future. Consequently soil microbial activity initiates the decreased N concentration in sediment and increased N concentration in overlying water in riparian wetland ecosystems.     

Influence of Nitrogen on Growth,Yield, and Yield Components and Nitrogen Uptake and Use Efficiency in Dry Bean Genotypes

Dry bean is an important legume and nitrogen (N) deficiency is one of the most yield-limiting factors in most of the bean-growing regions. A greenhouse experiment was conducted with the objective to determine influence of N on growth, yield, and yield components and N uptake and use efficiency of 23 dry bean genotypes. Straw yield, grain yield, yield components, maximum root length, and root dry weight were significantly increased with the addition of N but varied with genotypes. The N × genotype interactions were also significant for most of these traits, indicating variation in responses of genotypes with the variation in N levels. There was significant difference in N uptake and use efficiency among genotypes. Most of growth and yield components were significantly and positively associated with grain yield. Based on grain yield efficiency index (GYEI), genotypes were classified into efficient, moderately efficient, or inefficient group in N-use efficiency. Nitrogen concentration was greater in grain compared to straw, indicating greater N requirement of dry bean genotypes.     

Genotypic variation in rice for grain yield and quality as affected by salt-affected field conditions

A field experiment was conducted under two natural field conditions at the Research Farm (normal soil) and Proka Farm (salt-affected soil) of The Institute of Soil and Environmental Sciences (ISES), University of Agriculture, Faisalabad, Pakistan, to evaluate the performance of 11 rice genotypes in normal and salt-affected conditions. The experiment was laid out in randomized complete block design (RCBD) with three replications. The gas exchange attributes were measured at vegetative stage whereas the grain and straw yields and the yield components were recorded at maturity. After harvesting, the ionic parameters including sodium (Na⁺) and potassium (K⁺) were determined. Afterward, grain quality in terms of length, width, milling recovery, broken fraction, and chalkiness was also determined for the selected genotypes. Salt-affected conditions adversely affected the physiology, yield, and quality of the tested genotypes. The genotypes KS-282 followed by Shaheen Basmati showed significantly higher photosynthetic rate, transpiration rate, and stomatal conductance under both normal and salt-affected conditions, whereas the genotypes 99404 followed by 99417 showed minimum values of gas exchange attributes. The grain and straw yields were the highest in the case of KS-282 at both sites, whereas the lowest grain and straw yields were observed in the case of 99440 followed by 99417 under both normal and salt-affected conditions. Regarding the quality attributes, Super Basmati produced longer grains but with higher broken fraction and lower milling recovery, whereas the reverse was observed in the case of KS-282.     

Liming and Copper Fertilization in Dry Bean Production on an Oxisol in No-tillage System

ABSTRACT

A field study was conducted with the objective of determining response of dry bean (Phaseolus vulgaris L.) to liming and copper (Cu) fertilization applied to an Oxisol. The lime rates used were 0, 12, and 24 Mg ha^?1 and Cu rates were 0, 2.5, 5, 10, 20, and 40 kg Cu ha^?1. Liming significantly increased common bean grain yield. Liming also significantly influenced soil chemical properties in the top (0–10 cm) as well as in the sub (10–20 cm) soil layer in favor of higher bean yield. Application of Cu did not influence yield of bean significantly. Average soil chemical properties across two soil layers (0–10 and 10–20 cm) for maximum bean yield were pH 6.4, calcium (Ca), 4.2 cmol_c kg^?1, magnesium (Mg) 1.0 cmol_c kg^?1, H+Al 3.2 cmol_c kg^?1, acidity saturation 40.4%, cation exchange capacity (CEC) 8.9 cmol_c kg^?1, base saturation 63.1%, Ca saturation 45.7%, Mg saturation 18.0%, and Potassium (K) saturation 2.9.     

Response of Cotton to Irrigation Methods and Nitrogen Fertilization: Yield Components,Water‐Use Efficiency,Nitrogen Uptake,and Recovery

Efficient crop use of nitrogen (N) fertilizer is critical from economic and environmental viewpoints, especially under irrigated conditions. Cotton yield parameters, fiber quality, water‐ and N‐use efficiency responses to N, and irrigation methods in northern Syria were evaluated. Field trials were conducted for two growing seasons on a Chromoxerertic Rhodoxeralf. Treatments consisted of drip fertigation, furrow irrigation, and five different rates of N fertilizer (50, 100, 150, 200, and 250 kg N /ha). Cotton was irrigated when soil moisture in the specified active root depth was 80% of the field capacity as indicated by the neutron probe.

Seed cotton yield was higher than the national average (3,928 kg/ha) by at least 12% as compared to all treatments. Lint properties were not negatively affected by the irrigation method or N rates. Water savings under drip fertigation ranged between 25 and 50% of irrigation water relative to furrow irrigation. Crop water‐use efficiencies of the drip‐fertigated treatments were in most cases 100% higher than those of the corresponding furrow‐irrigated treatments. The highest water demand was during the fruit‐setting growth stage. It was also concluded that under drip fertigation, 100–150 N kg/ha was adequate and comparable with the highest N rates tested under furrow irrigation regarding lint yield, N uptake, and recovery. Based on cotton seed yield and weight of stems, the overall amount of N removed from the field for the drip‐fertigated treatments ranged between 101 and 118kg and 116 and 188 N/ha for 2001 and 2002, respectively. The N removal ranged between 94 and 113 and 111 and 144 kg N/ha for the furrow‐irrigated treatments for 2001 and 2002, respectively.     

Determining Symbiotic Nitrogen Fixation in Dry Bean Cultivars Using Ureide Method and Isotope Dilution Techniques

Symbiotic nitrogen fixation (SNF) is an environmentally safe source of nitrogen (N) to the crop plants. In total, 12 dry bean (Phaseolus vulgaris L.) cultivars from pinto, navy, black, and kidney market classes were inoculated with rhizobia and grown in a greenhouse. SNF was estimated using isotope dilution technique and ‘ureide’ method. The amount of SNF ranged between 33 and 68 mg N plant^–1 when determined using ¹⁵N isotope dilution and followed the order: pinto > navy > black > kidney. Percent N derived from atmosphere (%Ndfa) significantly varied between 49% and 90% at V₃ and between 71% and 98% at R₂ stages. The outcomes of the experiment suggested that dry bean cultivars from different market classes have variable N₂ fixation ability, and fertilizer N required should be calculated according to their SNF potentials and N need of a specific market class or cultivar. Stable isotope dilution should be used as the standard procedure to estimate the SNF in dry bean.     

Corn Monoculture Yield Response to Fertilization and Nitrate Nitrogen Distribution

The objectives of this study were to determine the effects of fertilization system, nitrate (NO₃)– nitrogen (N) distribution along soil profile, and their interaction on corn yield. The study was conducted at the experimental field of Institute of Field and Vegetable Crops in Novi Sad (Serbia) during 2001–2004. Corn monoculture included four fertilization variants: control (Ø), nitrogen–phosphorus–potassium (NPK) mineral fertilizers, mineral fertilizer + corn stalks (NPK + S), and mineral fertilizers + manure (NPK + M). The greatest yield was found in the variant NPK + M (9.25 t ha^?1). Path coefficients showed that greatest direct positive effects on corn yield were exhibited by NO₃-N levels at soil depths of 60–90 cm and 30–60 cm. The path analysis showed that winter precipitation (WP) had a direct negative effect on yield performance. However, the effect of the downward movement of NO₃-N from the topsoil to deeper soil layers of WP on yield was positive.     

Nitrogen,Phosphorus and Potassium Interactions in Upland Rice

Upland rice is an important crop in South America, including Brazil. Nutrient interactions are important in determining crop yields. A greenhouse experiment was conducted to evaluate interaction among nitrogen (N), phosphorus (P), and potassium (K) in upland rice production. The treatments applied to upland rice grown on an Oxisol were three levels of N (N₀, N₁₅₀ and N₃₀₀ mg kg^?1), three levels of P (P₀, P₁₀₀ and P₂₀₀ mg kg^?1) and three levels of K (K₀, K₁₀₀ and K₂₀₀ mg kg^?1). These treatments were tested in a 3 × 3 × 3 factorial arrangement. Grain yield, shoot dry weight, plant height, root dry weight, maximum root length, panicle number, 1000-grain weight, and grain harvest index were significantly influenced by N, P, and K treatments. The treatment that did not receive P fertilization did not produce panicle or grain. Hence, P was most yield-limiting nutrient compared to two other nutrients. At the N₀P₀K₀ treatment, rice did not produce grains, indicating severe deficiency of these nutrients in Brazilian Oxisols. Maximum grain yield was obtained with the N₃₀₀P₂₀₀K₂₀₀ treatment. Grain yield had significant positive association with plant height, shoot dry weight, root dry weight, maximum root length, 1000-grain weight, panicle number, and grain harvest index. Among these growth and yield components, shoot dry weight had the highest positive association with grain yield and root length minimum positive association with grain yield. Hence, adopting adequate soil and crop management practices can improve growth and yield components and increase grain yield of upland rice.     

缓释尿素对两种土壤小麦氮素运转、产量和土壤无机氮的影响

为探明缓释尿素与普通尿素掺混比例对安徽小麦花后氮素运转特征和土壤氮素盈余的影响,分别选择安徽省北方小麦产区小麦—玉米轮作和南方小麦产区小麦—水稻轮作方式,土壤类型分别为两合土和黄棕壤,设置不施氮肥处理(CK)、农民习惯处理(Ncon)、减少普通尿素用量的优化氮素处理(Nopt)、缓释尿素及其掺混普通尿素处理(SRU1、SRU2、SRU3)和普通尿素全部基施处理(SRU4),分析了不同施肥处理在两种土壤上小麦花后氮素转运、产量、氮肥利用率和土壤无机氮积累量。结果表明:与黄棕壤比较,相同施肥处理两合土上小麦产量、花后氮素积累量和氮素运转量显著增加,平均分别增加了71.8%,199.1%和25.8%,而氮素转移率和土壤氮素表观盈余量平均分别降低16.1%和49.7%。在两种土壤上,与Ncon比较,缓释尿素及其掺混普通尿素处理小麦产量差异不大,显著提高了氮肥利用率,黄棕壤和两合土上增幅分别达43.7%~91.9%和6.6%~26.9%,以缓释尿素掺混普通尿素比例2∶1处理(SRU2)最高;与Nopt相比,仅两合土上SRU2氮肥利用率显著提高。在小麦生育后期,农民习惯施肥处理0—30cm土壤NO_3~-—N和NH_4~+—N积累量明显高于缓释尿素处理,且土壤氮素盈余量高于其他处理。缓释尿素与尿素掺混实现了一次性简化施肥,可保障小麦产量、提高氮肥利用率、减少土壤氮素盈余量及降低环境污染风险。     

Macronutrient-Use Efficiency and Changes in Chemical Properties of an Oxisol as Influenced by Phosphorus Fertilization and Tropical Cover Crops

Cover crops are important components of copping systems due to their beneficial effects on soil physical, chemical, and biological properties. A greenhouse experiment was conducted to evaluate influence of phosphorus (P) fertilization on nutrient-use efficiency of 14 tropical cover crops. The P levels tested were 0 (low), 100 (medium), and 200 (high) mg kg^?1 of soil. The cover crops tested were Crotalaria breviflora, Crotalaria breviflora, Crotalaria spectabilis Roth, Crotalaria ochroleuca G. Don, Crotalaria juncea L., Crotalaria mucronata, Calapogonium mucunoides, Pueraria phaseoloides Roxb., Pueraria phaseoloides Roxb., Cajanus cajan L. Millspaugh, Dolichos lablab L., Mucuna deeringiana (Bort) Merr., Mucuna cinereum L., and Canavalia ensiformis L. DC. Agronomic efficiency (shoot dry weight per unit P applied), physiological efficiency (shoot dry weight per unit of nutrient uptake), and apparent recovery efficiency (nutrient uptake in the shoot per unit nutrient applied) were significantly varied among cover crops. Agronomic efficiency decreased with increasing P levels. Overall, physiological efficiency of nutrient uptake was in the order of P > sulfur (S) > magnesium (Mg) > calcium (Ca) > potassium (K) > nitrogen (N). Similarly, apparent recovery efficiency was in the order of N > K > Ca > Mg > P > S. Different recovery efficiency in cover crops can be useful in selecting cover crops with high recovery efficiency, which may be beneficial to succeeding crops in the cropping systems. The P × cover crops interactions were significant for soil extractable Ca²⁺, P, cation exchange capacity (CEC), Ca saturation, Ca/K ratio, and K/Mg ratio, indicating that cover crops change these soil property differently under different P levels. Thus, cover crops selection for different P levels is an important strategy for using cover crops in cropping systems in Brazilian Oxisols. Optimal values of soil pH, soil Ca and Mg contents, hydrogen (H) + aluminum (Al), P, CEC, base saturation, Ca saturation, Mg saturation, and K saturation were established for tropical cover crops grown on an Oxisol.     

施肥对旱地胡麻耗水特性和籽粒产量的影响

为了合理调控胡麻生产过程中氮、磷配施水平,以"陇亚杂1号"为试验材料,研究了不同施肥处理对旱地胡麻耗水特性、籽粒产量和水分利用效率的影响。试验设2个施氮(纯N)水平:75kg/hm~2(N_1),150kg/hm~2(N_2);2个施磷(纯P_2O_5)水平:75kg/hm~2(P_1),150kg/hm~2(P_2),共4个施肥处理(N_1P_1,N_1P_2,N_2P_1和N_2P_2),以不施氮磷肥为对照(N_0P_0)。结果表明:2013年胡麻的农田耗水量随着施肥量的增加而增加,2014年随着施肥水平增加至N2P1时,耗水量达到高峰,较N_2P_2处理显著增加10.23%;与N0P0处理相比,各施肥处理100—200cm土层的耗水量明显增加13.03~19.36mm。在胡麻现蕾至盛花期,2013年各施肥处理在此阶段的耗水量随着施肥量的增加而增加,而2014年以N_2P_1处理的阶段耗水量最大,较N_0P_0,N_2P_2处理分别显著增加19.25%和17.87%,说明氮磷配施有利于促进胡麻根系对土壤水分的吸收,尤其是深层贮水的利用,以满足胡麻生育后期的水分需求。两个生长季,胡麻的籽粒产量均表现为N_2P_1N_2P_2N_1P_2N_1P_1N_0P_0,且N_2P_1的籽粒产量显著高于N_0P_0处理44.27%~56.55%。胡麻的水分利用效率与籽粒产量的变化趋势基本一致,各施肥处理中以N_2P_1处理的最大,N_2P_2的次之,分别比N_0P_0处理显著增加30.23%~38.54%,20.50%~36.81%。可见,在本试验区同等肥力土壤条件下,氮磷施用量分别为150kg/hm~2,75kg/hm~2的高氮低磷配施(N_2P_1)是旱地胡麻高产节肥的最佳施肥处理。     

The Leaching Behaviour and Balances of Nitrogen and Other Elements under Spring Wheat in Lysimeter Experiment 1985–92

Abstract

In a lysimeter study it was found that moderate rates of ammonium nitrate increased utilization percentages in spring wheat, and the leaching was 10% or less of added N. Over-optimal rates reduced utilization percentages and increased leaching to almost 50% of the highest doses. Late split application of calcium nitrate increased the percentage of N in grain. Furthermore, leaching of N was not reduced, but occurred somewhat later in the fall and winter seasons. Leaching of Cl^? was more rapid and that of SO₄ ^2- was delayed relative to the leaching of NO₃ ^?. Rather large negative N balances were obtained, also after over-optimal application rates, and total N content of the soil was reduced. Compared with the N₀ treatment, differences in soil N residues amounted to 15–25% of added N in seven years. Gaseous losses had apparently taken place both from the added N and from soil N according to the total-N analysis.     

中国地区小麦产量及产量要素对秸秆还田响应的整合分析

为探究秸秆还田对中国小麦的增产效果,运用整合分析方法定量分析秸秆还田后小麦产量及产量要素的变化范围,并探讨不同秸秆还田条件的影响;通过文献检索与严格筛选,整理得到55篇田间试验数据资料,建立小麦产量及产量要素数据库,并应用整合分析方法,比较分析秸秆还田对小麦产量和产量要素的整体影响以及秸秆还田技术的适用条件。结果表明,总体上秸秆还田能够显著增加小麦产量和产量要素,但增长幅度不大。通过分析其影响因素发现,在黄河流域到长江流域之间的省份,选择潮土、塿土、水稻土等养分中等、复杂难以利用的土壤类型,实行秸秆还田技术的收益较好;不同耕作方式对秸秆还田的影响较大,免耕和翻耕技术好于旋耕技术;施氮水平>300 kg·hm^-2时,增产不显著,200～300 kg·hm^-2施氮水平为最佳;秸秆种类与还田量对小麦的增产效果影响较大,其中使用麦秸还田效果一般,稻秸全量或半量还田成效较好,玉米秸半量还田(6 000 kg·hm^-2)增产最大。综上,秸秆还田能够增加小麦产量和产量因素,秸秆还田的最佳条件为在秦岭-淮河一线南北地区实行免耕与翻耕交替耕作方式,采用玉米秸秆半量还田方法,施氮水平为200～300 kg·hm^-2。本研究结果为秸秆还田在我国小麦高产高效技术的应用提供了理论参考。     

不同施氮方式对嘎啦苹果碳氮利用和产量品质的影响

以15年生嘎啦苹果/平邑甜茶为试材,采用C、N双标记技术,研究果实发育期不同施氮方式(传统一次性施氮、分次施氮和渗灌施氮,分别用ON、TN和IN表示)对苹果植株碳氮营养吸收、利用、分配、损失及果实产量和品质的影响。结果表明:至果实成熟期,苹果各器官Ndff值均为INTNON,新生器官间(果实、叶片和1年生枝)差异显著。植株全氮量和~(15)N吸收量均以IN处理最大,ON处理最低。与ON处理相比,TN和IN处理~(15)N利用率分别提高了41.63%和68.60%,而~(15)N损失率分别降低了10.60%和18.63%。各处理不同土层~(15)N残留量差异显著,0—40 cm土层~(15)N残留量为INTNON,60—120 cm土层趋势相反。TN和IN处理果实和贮藏器官(多年生枝、中心干和粗根)的~(13)C分配率均显著高于ON处理,而营养器官(叶片和1年生枝)的~(13)C分配率则以ON处理最高,IN处理最低。同时,在IN处理下,苹果产量、硬度、可溶性糖和糖酸比等品质指标均达到最高水平。综上,渗灌施氮通过降低氮素损失,显著促进植株对氮素的吸收利用,并优化光合产物在各器官间分配,从而最有利于苹果产量和品质的提高。     

减氮和机械侧深施肥对机插杂交稻产量及氮素吸收利用的影响

为探究侧深减量施缓释肥对水稻生长、氮素利用及土壤肥力等的影响,本研究以两系杂交稻品种晶两优534和三系杂交稻品种宜香优2115为供试材料,通过设置R₁₅₀(一次性机械侧深施缓释肥150 kg·hm^-2)、R₁₂₀(一次性机械侧深减氮20%施缓释肥120 kg·hm^-2)、R₉₆N₂₄ (基肥侧深施缓释肥96 kg·hm^-2, 穗肥撒施尿素24 kg·hm^-2)、N₁₅₀(基肥人工撒施尿素90 kg·hm^-2,穗肥撒施尿素60 kg·hm^-2)、N₀(不施氮肥)5种不同的氮肥施用处理,分析机械侧深减氮施肥对机插稻产量形成和氮素吸收利用效率的影响。结果表明,与常规施肥相比,侧深施用缓释肥显著提高了机插稻分蘖数、氮素积累量、氮肥利用率和土壤肥力,对机插稻产量和氮素利用存在显著影响。侧深施缓释肥显著提高了机插稻的有效穗数和每穗粒数,两品种均以一次性机械侧深施用常规施氮量缓释肥处理(R₁₅₀)的产量最高,比2次人工撒施常规尿素处理(N₁₅₀)平均增产13.05%。采用机械侧深施肥,减氮20%的“基缓追速”处理(R₉₆N₂₄)产量均高于与人工撒施常规施氮量处理(N₁₅₀)。R₉₆N₂₄的氮肥农学利用率、氮肥吸收利用率和产量均高于N₁₅₀。综上所述,与人工撒施常规尿素相比,采用机械侧深施基肥能保证水稻整个生育期对氮素的需求,显著提高机插稻氮素利用率;缓释肥减量20%侧深施可保持土壤肥力和产量不减,达到减氮稳产的目的。本研究结果为机插稻优质绿色高效生产提供了理论依据和实践指导。     

Study on the Effects of Organic and Inorganic Nitrogen Fertilizer on Yield,Yield Components,and Nodulation State of Chickpea (Cicer arietinum L.)

To study the effects of organic and inorganic nitrogen (N) on yield and nodulation of chickpea (Cicer arietinum L.) cv. ILC 482, a spilt-plot experiment based on randomized complete block design with four replications was conducted in 2008 at the experimental farm of the Agriculture Faculty, University of Mohaghegh, Ardabili. Experimental factors were inorganic N fertilizer at four levels (0, 50, 75, and 100 kg ha^?1) in the main plots that applied in the urea form, and two levels of inoculation with Rhizobium bacteria (with and without inoculation) as subplots. Nitrogen application and Rh. inoculation continued to have positive effects on yield and its attributes. The greatest plant height, number of primary and secondary branches, number of pods per plant, number of filled and unfilled pods per plant, number of grains per plant, grain yield, and biological yield were obtained from the greatest level of N fertilizer (100 kg urea ha^?1) and Rh. inoculation. Application of 75 and 100 kg ha^?1 urea showed no significant difference in these traits. Furthermore, the greatest rate of N usage (100 kg urea ha^?1) adversely inhibited nodulation of chickpea. Number and dry weight of nodules per plant decreased significantly with increasing N application rate. The lowest values of these traits recorded in application of 100 kg ha^?1 urea. Results indicated that application of suitable amounts of N fertilizer (i.e., between 50 and 75 kg urea ha^?1) as starter can be beneficial to improve nodulation, growth, and final yield of inoculated chickpea plants.     

Phosphorus Nutrition of Upland Rice,Dry Bean,Soybean, and Corn Grown on an Oxisol

Rice, dry bean, corn, and soybean are important food crops. Phosphorus (P) deficiency is one of the most yield-limiting factors for these crops grown on highly weathered Brazilian Oxisols. Four greenhouse experiments were conducted to determine P requirements of these four crops. The P levels used were 0, 50, 100, 200, and 400 mg kg^?1. Growth, yield, and yield components evaluated of four crop species were significantly increased with the application of P fertilization. Most of the responses were quadratic in fashion when the P was applied in the range of 0 to 400 mg kg^?1. Maximum grain yield of upland rice was obtained with the application of 238 mg P kg^?1 of soil, maximum dry bean grain yield was obtained with the application of 227 mg P kg^?1 of soil, and maximum grain yield of soybean was obtained with the application of 224 mg P kg^?1 of soil. Maximum shoot growth of corn was obtained with the addition of 323 mg P kg^?1 of soil. Most of the growth and yield components had significant positive association with grain yield or shoot dry weight. Phosphorus concentration and uptake were greater in the grain compared to straw in upland rice and dry bean plants. Overall, P-use efficiencies decreased with increasing P rates.