Productivity of capsicum influenced by conjoint application of isolated indigenous PGPR and chemical fertilizers

Inorganic fertilizers alone cannot sustain high levels of productivity. This study was conducted to determine whether higher productivity of capsicum could be achieved by conjoint application of chemical fertilizers and plant growth promoting rhizobacteria (PGPR). Four PGPR isolates (RS₂, RS₃, RS₄, and RS₇) from capsicum roots and rhizosphere were evaluated at Solan, Himachal Pradesh (India), during 2009–2012. Two best performers: RS₂ and RS₇ were tried singly or in consortium with different levels of chemical fertilizers under field conditions, Randomized Block Design, replicated thrice. The conjoint use of 100% recommended nitrogen, phosphorus, and potassium (NPK) doses through chemical fertilizers (RDF) plus PGPR significantly increased fruit yield, plant height, and biomass by 37%, 20%, and 30%, respectively, over sole application of 100% RDF (control). Further, response of capsicum to 80% RDF plus PGPR was statistically comparable with control. The results, therefore, indicate the potential of isolated PGPR strains to substitute about 20% NP fertilizers besides enhanced productivity of capsicum.     

Effects of mineral and biofertilizers on barley growth on compacted soil

Abstract

Biofertilizers are an alternative to mineral fertilizers for increasing soil productivity and plant growth in sustainable agriculture. The objective of this study was to evaluate possible effects of three mineral fertilizers and four plant growth promoting rhizobacteria (PGPR) strains as biofertilizer on soil properties and seedling growth of barley (Hordeum vulgare) at three different soil bulk densities, and in three harvest periods. The application treatments included the control (without bacteria inoculation and mineral fertilizers), mineral fertilizers (N, NP and P) and plant growth promoting rhizobacteria species (Bacillus licheniformis RC04, Paenibacillus polymyxa RC05, Pseudomonas putida RC06, and Bacillus OSU-142) in sterilized soil. The PGPR, fungi, seedling growth, soil pH, organic matter content, available P and mineral nitrogen were determined in soil compacted artificially to three bulk density levels (1.1, 1.25 and 1.40 Mg m^?3) at 15, 30, and 45 days of plant harvest. The results showed that all the inoculated bacteria contributed to the amount of mineral nitrogen. Seed inoculation significantly increased the count of bacteria and fungi. Data suggest that seed inoculation of barley with PGPR strains tested increased root weight by 9–12.2%, and shoot weight by 29.7–43.3% compared with control. The N, NP and P application, however, increased root weight up to 18.2, 25.0 and 7.4% and shoot weight by 31.6, 43.4 and 26.4%, respectively. Our data show that PGPR stimulate barley growth and could be used as an alternative to chemical fertilizer. Soil compaction hampers the beneficial plant growth promoting properties of PGPR and should be avoided.     

Enhancing micronutrient uptake and yield of wheat through bacterial PGPR consortia

A pot experiment was undertaken under net house conditions, with three rhizobacterial strains AW1 (Bacillus sp.), AW5 (Providencia sp.) and AW7 (Brevundimonas sp.), applied along with 2/3 recommended dose of nitrogen (N) and full dose of phosphorus (P) and potassium (K) fertilizers (N₉₀P₆₀K₆₀). An enhancement of 14–34% in plant biometric parameters and 28–60% in micronutrient content was recorded in treatments receiving the combination of AW1?+?AW5 strains, as compared to full dose of fertilizer application. The treatment involving inoculation with AW5?+?AW7 recorded highest values of % P and N, with a two-fold enhancement in phosphorus and 66.7% increase in N content, over full dose application of P and K fertilizers. A significant correlation was recorded between plant biomass, panicle weight, grain weight, N, P and iron (Fe) with acetylene reduction activity, indicating the significance of N fixation in overall crop productivity. Our study illustrates the multiple benefits of plant growth promoting rhizobacteria (PGPR) inoculation in integrated nutrient management and biofortification strategies for wheat crop.     

Effect of Indigenous Plant Growth-Promoting Rhizobacteria on Wheat (Triticum Aestivum L.) Productivity and Soil Nutrients

The present study aimed at selection of efficient bacterial isolates with multiple plant growth-promoting (PGP) traits at variable doses of chemical fertilizers for enhanced wheat productivity and sustenance of soil health. Ten bacterial isolates from wheat (rhizosphere soil and root endosphere) were screened for PGP traits (indole acetic acid, phosphate solubilization, siderophore production, and ammonia production). Only three isolates (B2, SIR1, and BIS2) possessed all PGP traits. Net house evaluation of these isolates at graded doses of chemical fertilizers revealed that the potential of B2 isolate is significantly superior for enhancing wheat yield and soil properties. On the basis of 16S rDNA analysis, the potential isolate (B2) was identified as Serratia marcescens. Conjoint use of the B2 isolate at 80% recommended doses of fertilizers (RDF) significantly increased wheat growth and saved 18 kg nitrogen and 10 kg phosphorous on per hectare basis. The developed module not only increases profitability but also protects the environment and sustains soil health.     

应用PGPR菌肥减少烤烟生产化肥的施用量

利用从烤烟根际筛选的抗生菌、固氮菌、解磷菌和解钾菌菌株制成PGPR菌肥,进行田间完全区组随机试验,研究其在减施化肥的条件下对烤烟产量质量的影响。试验地土壤类型为黄棕壤,种植烤烟品种为云烟89,菌肥施用量30 kg hm-2,于烤烟移栽时溶于生根水中一起施入。共设4个处理,分别是(1)常规施肥同时施用PGPR菌肥;(2)NPK肥为常规施肥的80%同时施用PGPR菌肥;(3)常规施肥;(4)NPK肥为常规施肥的80%。结果表明,施用菌肥的二处理与未施用菌肥的二处理相比,施用菌肥不同生长期烤烟根际放线菌的数量显著降低17%～27%(p<0.05),根际微生物生物量碳含量提高3%～16%,现蕾期根际解磷菌的数量显著提高24%(p<0.05),并可提高烤烟的抗病性,烤后烟外观质量好。处理(2)与处理(4)比较,现蕾期烤烟根际氮、钾、铜、锌、硼和铁6种元素的有效性提高4.46%～28.87%,而磷、钙、镁和锰4种矿质元素的有效性降低2.63%～30.19%,烤烟产量和净产值分别提高7.53%和30.05%。处理(2)与处理(3)比较,烤烟产量和净产值分别提高4.52%和24.68%。使用PGPR菌肥可适当减少化肥用量,为可持续生产优质、无公害烟叶的有效途径之一。     

Soil Chemical Properties and Growth and Nutrient Uptake of Maize Grown with Different Combinations of Broiler Litter and Chemical Fertilizer in a Calcareous Soil

The main objective of this study was to explore the interactive influence of broiler litter and chemical nitrogen (N)–phosphorus (P) fertilizers placed with furrower and with disk + furrower on maize yield and soil chemical properties. The experiment consisted of two methods of fertilizer placements and seven fertilizer treatments conducted for two successive years under field conditions. Results showed that furrower method improved soil chemical properties and subsequently increased maize grain yield and dry-matter production compared with the disk + furrower method. The N and P levels in soil increased with the application of NP fertilizers and broiler litter. Soils amended with broiler litter and NP fertilizers had greater maize grain yield and dry-matter production than the control. In conclusion, furrower placement combined with the application of broiler litter and 20% of the optimum chemical NP fertilizers were the most efficient nutrient management practice for increasing maize performance in the studied area.     

长期不同培肥措施下玉米产量稳定性及棕壤氮素累积分布特征

  【目的】  研究长期不同培肥措施下玉米产量的稳定性、可持续性和土壤矿质氮累积分布、微生物量氮含量特征,为制定合理的施肥措施和保证东北棕壤地区农业的可持续绿色发展提供理论依据。  【方法】  棕壤肥料长期定位试验始于1979年。选取其中的12个处理:不施肥对照(CK)、单施氮肥(N)、氮磷肥配施(NP)、氮磷钾肥配施(NPK)、低量有机肥(M1)及其与化肥配施(M1N、M1NP和M1NPK)、高量有机肥(M2)及其与化肥配施(M2N、M2NP和M2NPK),分析长期施肥下玉米产量的变化,并于2018年在玉米收获期采集植株和土壤样品,阐明玉米地上部吸氮量变化,0—100 cm土层土壤矿质氮分布、累积及微生物量氮含量的差异。  【结果】  长期不同施肥下玉米产量呈波动变化,且在1979—1998年内玉米产量变化趋势较平稳,1999—2018年内变幅较大。M1NPK、M2NPK处理玉米平均产量最高,在试验前20年较NPK处理分别提高了10.3%、11.7%,后20年分别提高了17.1%、19.4%。随着试验年限增加,玉米产量的稳定性和可持续性增加,有机肥配施化肥各处理高于单施化肥处理,在试验前20年和后20年玉米产量的可持续性指数(SYI)介于0.43～0.58和0.50～0.67,低量有机肥配施处理高于高量有机肥配施处理。配施有机肥各处理肥料贡献率高于单施化肥处理,且试验后20年M1NPK处理肥料贡献率最高,达54%。施肥40年后(2018年)玉米地上部吸氮量以M1NPK处理最高(302 kg/hm2),与M2NPK处理差异不显著。配施低量有机肥玉米收获期80—100 cm土层土壤矿质氮含量较低,M1NPK处理 0—100 cm土层土壤矿质氮贮量为127 kg/hm2,显著低于M1N和M1NP处理。而高量有机肥配施各处理0—100 cm土层土壤矿质氮贮量较化肥试区和低量有机肥试区分别增加了324.5%和172.9%,增加了氮素损失风险。此外,长期配施有机肥处理0—40 cm土层土壤微生物量氮含量增加,但低量和高量有机肥试区各处理间差异不显著。  【结论】  长期不同培肥措施会影响玉米产量的稳定性和可持续性,改变土壤氮素分布和累积,进而影响玉米氮素吸收。低量有机肥(13.5 t/hm2)配施氮磷钾化肥可促进玉米生长和氮素吸收,降低0—100 cm土层土壤矿质氮贮量,降低氮素损失风险,增加微生物量氮含量,较高的微生物量氮又可作为有机氮库来增加土壤供氮并固持易损失的矿质氮和肥料氮,以保证玉米的高产稳产和环境友好。     

Synergetic use of biochar and synthetic nitrogen and phosphorus fertilizers to improves maize productivity and nutrient retention in loamy soil

Abstract

This study was designed to investigate the effect of biochar on maize production and nutrient retention with recommended full and half dose of nitrogen (N) and phosphorus (P) nutrition in loamy soil. In the first study, maize was grown in pots with four levels of biochar (0, 2, 4, and 6?t?ha^?1) under two levels of NP fertilizer, viz. recommended (200–150?kg?NP?ha^?1) and it’s half (100–75?kg?NP?ha^?1) dose. The prominent improvement in plant roots traits, leaf area, plant growth, morphological and yield-related parameters were observed with addition of biochar at 2 and 4?t?ha^?1; while, plant height, number of grains per cob, grains and biological yield decreased with biochar addition 6?t?ha^?1 along with full dose of NP nutrition. In subsequent field studies, two levels of biochar along with control (0, 2, 4?t?ha^?1) were investigated. The more improvement in root growth, leaf area and crop growth was observed when biochar was applied at 2?t?ha^?1 with full NP nutrition. Biochar application at 2?t?ha^?1 with full NP nutrition produced the highest grain yield (6.64?t?ha^?1); however, biochar addition (2?t?ha^?1) with half NP nutrition resulted in better grain yield than full dose of NP to enhance maize production as compared with full dose of NP without biochar. Therefore, biochar addition (2?t?ha^?1) with half-recommended dose of NP prominently improved the maize productivity in loamy soil and serve as better in replacement of full dose of NP fertilizer.     

Bacterial inoculants for rice: effects on nutrient uptake and growth promotion

Beneficial soil bacteria are able to colonize plant root systems promoting plant growth and increasing crop yield and nutrient uptake through a variety of mechanisms. These bacteria can be an alternative to chemical fertilizers without productivity loss. The objectives of this study were to test bacterial inoculants for their ability to promote nutrient uptake and/or plant growth of rice plants subjected to different rates of chemical fertilizer, and to determine whether inoculants could be an alternative to nitrogen fertilizers. To test the interaction between putatively beneficial bacteria and rice plants, field experiments were conducted with two isolates: AC32 (Herbaspirillum sp.) and UR51 (Rhizobium sp.), and different nitrogen fertilization conditions (0%, 50%, and 100% of urea). Satisfactory results were obtained in relation to the nutrient uptake by plants inoculated with both isolates, principally when the recommended amount of nitrogen fertilizer was 50% reduced. These bacterial strains were unable to increase plant growth and grain yield when plants were subjected to the high level of fertilization. This study indicated that the tested inoculant formulations can provide essential nutrients to plants, especially when the levels of nitrogen fertilizers are reduced.     

Antifungal and Plant Growth Promoting Activities of Indigenous Rhizobacteria Isolated from Maize (Zea mays L.) Rhizosphere

Plant growth promoting rhizobacteria (PGPR) enhance the plant growth directly by assisting in nutrient acquisition and modulating plant hormone levels, or indirectly by decreasing the inhibitory effects of various pathogens. The aim of this study was to select effective PGPR from a series of indigenous bacterial isolates by plant growth promotion and antifungal activity assays. This study confirmed that most of the isolates from maize rhizosphere were positive for PGPR properties by in vitro tests. Azotobacter and Bacillus isolates were better phosphate solubilizers and producers of lytic enzymes, hydrocyanic acid (HCN), and siderophores than Pseudomonas. Production of indole-3-acetic acid (IAA) and antifungal activity were the highest in Azotobacter, followed by Bacillus and Pseudomonas. The most effective Azotobacter isolates (Azt₃, Azt₆, Azt₁₂) and Bacillus isolates (Bac_10, Bac₁₆) could be used as PGPR agents for improving maize productivity. Further selection of isolates will be necessary to determine their efficiency in different soils.     

Integrated Use of Nitrogen Fertilization and Microbial Inoculation: Change in the Growth and Chemical Composition of White Cabbage

Field experiments were conducted to evaluate the impact of seed and seedling inoculation by plant growth promoting rhizobacteria (PGPR) on nitrogen use efficiency, growth, yield, and chemical composition of cabbage at varying levels of nitrogen (N). Data revealed that N alone or in combination with PGPR either as seed or seedling inoculation significantly improved growth, yield, and nutrients of cabbage. PGPR inoculations were more efficient than non-inoculated controls in terms of yield and yield parameters. This study showed that seed and seedling inoculation increased yield and yield parameters as well as chlorophyll reading value and stomatal conductance versus controls. Applications of mineral fertilizers with microbial applications save 25% of mineral fertilizers yet give 33% more yield versus full doses of mineral application without microbial applications. Both seed and seedling treatments increased the nitrogen use efficiency (NUE) rates by 45, 53, 58, 45, and 40%, and 49, 59, 68, 69, 60, and 55%, respectively.     

Study the Effects of Siderophore-Producing Bacteria on Zinc and Phosphorous Nutrition of Canola and Maize Plants

Plant growth-promoting rhizobacteria (PGPR) are soil bacteria that are able to colonize rhizosphere and to enhance plant growth by means of a wide variety of mechanisms. In the present study, Myristica yunnanensis and Stenotrophomonas chelatiphaga strains were recognized as new records in Iran flora. According to the results, these strains significantly affected plants’ zinc and phosphorous contents which could be due to the production of phytosiderophore. Siderophore-producing bacteria increased canola zinc (Zn) content as strategy-I plant, while in maize, it can be said that probably the effect of phytosiderophore produced by plant on increasing root and shoot Zn content was more than siderophore produced by bacteria. These isolates could be used as bio-input for improving the plant productivity as a substitute to chemical fertilizers and also to correct the nutrient deficiencies in canola and maize for sustainable agriculture.     

腐植酸与氮肥配施对冬小麦氮素吸收利用及产量的影响

研究腐植酸与氮肥配施对冬小麦产量、氮素吸收及经济效益的影响,可为提高氮肥的增产效益,减少氮肥对生态环境的污染提供理论指导。在河南褐土区冬小麦-夏玉米轮作制度下,于2014年开始在河南省南阳市卧龙区开展田间定位试验,共设置单施磷钾肥、常规施肥、单施腐植酸、常规施肥+腐植酸、常规施肥减氮15%+腐植酸、常规施肥减氮30%+腐植酸6个处理,分析不同氮肥与腐植酸配施下冬小麦产量和氮肥利用的特征。结果表明,腐植酸与氮肥配施可以有效提高冬小麦的产量及其构成要素,促进植株对氮素的累积,提高氮肥利用率。其中,常规施肥减氮15%+腐植酸处理下冬小麦产量、籽粒氮含量、籽粒氮累积量、地上部总氮累积量、氮肥利用效率和纯收益均增加,与常规施肥相比,冬小麦产量增加4.96%,氮肥利用效率增加23.42%,纯收益增加2.18%。常规施肥减氮30%+腐植酸条件下冬小麦产值和收益降低。因此,在施用腐植酸的基础上,配施适量氮肥才能获得较高的产值和收益。常规施肥减氮15%+腐植酸是本研究区域最佳的施肥模式,对实现现代化农业生产的高产高效、资源节约和生态环境保护具有重要意义。     

不同施肥措施对黑土区玉米氮效率及碳排放的影响

[目的]以东北黑土区玉米生产体系为研究对象,探究不同施肥措施对玉米籽粒产量、氮肥利用效率及碳排放的影响,以实现该地区粮食平稳增产的同时降低农业生产碳排放.[方法]在黑龙江典型黑土区进行了两年玉米田间试验,试验设5个处理:不施氮肥(CK);推荐施肥处理(RF);推荐施肥+有机氮替代20％化肥氮(MRF);推荐施肥+秸秆还...     

How different long‐term fertilization strategies influence crop yield and soil properties in a maize field in the North China Plain

The impact of fertilization on maize (Zea mays L.) yield and soil properties was investigated in a long‐term (> 18 y) experimental field in N China. A completely randomized block design with seven fertilizer treatments and four replications was used. The seven fertilizer treatments were (1) compost (COMP), (2) half compost plus half chemical fertilizer (COMP1/2), (3) balanced NPK fertilizer (NPK), (4–6) unbalanced chemical fertilizers without one of the major elements (NP, PK, and NK), and (7) an unamended control (CK). In addition to maize yield, soil chemical and biological properties were investigated. Compared to the balanced NPK treatment, maize yield from the COMP treatment was 7.9% higher, from the COMP1/2 was similar, but from the NP, PK, NK, and CK treatment were 12.4%, 59.9%, 78.6%, and 75.7% lower. Across the growing season, microbial biomass C and N contents, basal soil respiration, and fluorescein diacetate hydrolysis, dehydrogenase, urease, and invertase activities in the COMP and COMP1/2 treatments were 7%–203% higher than the NPK treatment. Values from all other treatments were up to 60% lower than the NPK treatment. Maize yield is closely related to the soil organic C (OC) and biological properties, and the OC is closely related to various biological properties, indicating that OC is a suitable indicator for soil quality. Our results suggest the most limiting nutrient for improving the yield or soil quality was P, followed by N and K, and balanced fertilization is important in maintaining high crop yield and soil quality. Additionally, increases in OC, N, and biological activities in COMP and COMP1/2 treatments imply that organic compost is superior to the chemical fertilizers tested.     

不同质地潮土夏玉米推荐施肥方法研究

为推动夏玉米科学施肥,在河南省砂壤、中壤和黏壤质潮土上采用田间试验研究了Nutrient Expert(NE)和Agro Services International Inc(ASI)法推荐施肥对夏玉米产量和经济效益的影响及基于NE推荐施肥的氮磷钾肥利用效率。结果表明,各推荐施肥处理夏玉米产量、纯收益和蛋白质产量均表现为黏壤>中壤>砂壤,NE推荐施肥处理的产投比最高,其次是ASI推荐施肥处理,推荐施肥可显著增加夏玉米植株养分积累量,促进籽粒产量和蛋白质产量的提高。在砂壤、中壤和黏壤上的NE推荐施肥处理比农民习惯施肥处理分别增产7.22%、3.84%和11.32%,ASI推荐施肥分别增产13.44%、10.60%和11.20%。NE推荐施肥处理中施氮对夏玉米的增产效应最大,氮肥农学效率和氮磷钾肥利用率均表现为黏壤>中壤>砂壤,磷、钾肥农学效率均表现为砂壤>黏壤>中壤,3种质地潮土的肥料农学效率均表现为磷肥>钾肥>氮肥。由此得出,NE推荐施肥适宜在黏壤质潮土推行,而ASI法推荐施肥适宜于砂壤和中壤质潮土。     

2021-01期封面+目录

  【目的】   农田氨挥发是大气中氨的重要来源,其减排措施研究已成为国际研究热点。有机肥替代化肥的农田氨挥发减排潜力已得到广泛认可,然而年际间气候变化对其减排能力的影响研究报道较少。通过研究年际间有机替代对作物产量和氨挥发损失量的影响,为华北地区科学减少氨挥发损失提供理论依据   【方法】   本研究基于华北平原玉米长期田间定位试验 (2007年设置),针对不同施肥处理开展了连续3年 (2017—2019年) 的氨挥发监测,以明确年际间气候变化对有机替代氨挥发减排潜力的影响强度。试验共设置4个处理:不施氮肥处理 (PK)、单施化肥处理 (NPK)、半量有机肥氮替代化肥氮处理 (HONS)、全量有机肥氮替代化肥氮处理 (FONS)。   【结果】   有机替代可以提高玉米产量,与NPK处理相比,HONS处理和FONS处理的玉米产量分别提高20.7%和30.9%。不同施氮处理的氮素偏生产力在35.6～46.7 kg/kg,与NPK处理相比,HONS处理和FONS处理的氮素偏生产力分别提高20.8%和30.9%。年际间和各处理间的氨挥发规律基本一致,都是在施肥后的第2～4天出现排放峰值,之后氨挥发速率逐渐降低,并在9天内基本趋于稳定。施肥后前9天是农田氨挥发的主要排放时期,氨挥发量占基肥期氨挥发总量的70.1%;占追肥期的63.7%。华北平原春玉米农田氨挥发损失量较低 (10.6 kg/hm2),有机替代能够进一步显著降低农田氨挥发损失。与NPK处理相比,HONS和FONS处理对氨挥发损失的减排率平均分别可达33.5%和58.7%。有机替代处理农田氨挥发的年际间变化显著高于单施化肥处理。相比氨挥发损失较低的2019年,2018年NPK处理的氨挥发损失增加了12.3%,而HONS处理和FONS处理分别增加了91.2%和105.0%,相应的HONS处理和FONS处理的减排率,从2019年的54.3%和71.1%,降低到22.1%和47.2%。主成分分析表明,年际间大气温度变化和土壤湿度变化是导致年际间氨挥发损失量差异的主要原因。   【结论】   相比单施化肥,有机肥替代化肥能够提高作物产量;相比半量有机替代,长期全量有机肥替代化肥对作物产量的提升能力更强。华北平原旱地农田有机替代能有效降低氨挥发损失,但在氨挥发损失较高年份有机替代的减排潜力会减弱,因此,有机替代氨挥发减排潜力的估算需要考虑年际间的变化。     

河南省玉米施肥效应对基础地力的响应

[目的]整理2005 2013年在河南省布置的885个玉米“3414”田间试验,分析不同地力水平下玉米施肥后的增产效果、经济效益及氮、磷、钾肥利用效率,明确不同地力水平下河南省玉米施肥效应,为科学施肥提供理论依据。[方法]选取其中5个处理CK(N0P0K0)、N(N0P2K2)、P(N2P0K2)、K(N2P2K0)和NPK(N2P2K2)的试验结果。按CK处理产量将供试885个试验地土壤基础地力划分为<4 t/hm^2、4~6 t/hm^2、6~8t/hm^2、>8 t/hm^2四个水平,收集了玉米施用氮、磷、钾肥的增产量、增产率、产值、施肥成本、施肥利润和产投比,计算了各施肥处理的农学效率、偏生产力、肥料贡献率、地力贡献率。[结果]四个地力水平的试验地样本量分别占总样本的15.35%、49.42%、29.42%、5.81%。NPK处理的增产量在四个地力水平下依次为3.04、2.49、1.88和1.12 t/hm^2,且各地力水平间差异显著。增产率表现出和增产量一样的变化趋势,且下降趋势更明显。基础地力产量<4 t/hm^2时,NPK处理的增产率平均达93.23%,而基础地力产量>8 t/hm^2仅为14.44%。在施肥经济效益方面,各施肥处理的产值、施肥利润及产投比均随地力水平的提高而升高,各地力水平间差异显著。其中NPK处理的产值、施肥利润及产投比在地力产量<4 t/hm^2时分别为10238元/hm^2、8862元/hm^2和5.75,在基础地力产量>8 t/hm^2时分别为15407元/hm^2、13736元/hm^2和8.05。河南省土壤地力对玉米产量的贡献率平均为69.99%,各地力水平下的地力贡献率随地力水平的提高而显著提高,四个地力水平的地力贡献率平均依次为53.24%、67.68%、78.80%和86.63%。土壤氮素、磷素、钾素地力贡献率平均分别为78.32%(40.72%~100%)、88.47%(70.40%~100%)、90.02%(78.27%~99.31%),总体以钾地力贡献率最大,磷地力贡献率次之,氮地力贡献率最小。从地力水平变化的角度来看,氮素、磷素、钾素地力贡献率均随地力水平的提高而逐渐增高,其中各地力水平下土壤氮素的地力贡献率分别为65.08%(<4 t/hm^2)、77.04%(4~6 t/hm^2)、85.32%(6~8 t/hm^2)、90.47%(>8 t/hm^2)。不同地力水平下各施肥处理的偏生产力随地力水平的提高而显著升高,农学效率和肥料贡献率总体随地力水平的提高而下降,说明提高基础地力可降低玉米产量对外源肥料的依赖性。[结论]提高土壤基础地力能够促进玉米增产、增收,降低玉米对外源肥料的依赖。河南省玉米生产中应重视土壤培肥,并根据不同地力水平合理施肥以保证玉米高产稳产、提高养分利用效率、节本增收。     

有机肥替代部分化肥对干旱区滴灌玉米养分吸收及产量影响

新疆是玉米高产区,但高产往往建立在化肥大量施用的前提下,研究有机肥替代部分化肥对新疆北疆干旱区滴灌玉米植株养分吸收及产量的影响,可为该地区化肥施用减量、生产成本降低、养分效率提高的新型施肥模式提供科学依据。通过田间小区试验,比较化肥和有机肥氮磷钾养分投入合计量相同,且生物有机肥替代8%、16%、24%化肥氮,或生物有机肥、牛粪、羊粪、玉米秸秆替代16%化肥氮对玉米养分吸收、产量、氮素效率及经济效益的影响。结果表明:与单施化肥相比,有机肥替代部分化肥可增加玉米干物质花后积累比例3.23%～11.81%,氮、钾养分花后吸收比例最大分别增加19.45%、15.44%,增加玉米产量8.50%～21.00%。有机肥替代部分化肥下总氮素表观利用率、偏生产力、生理利用率、贡献率较单施化肥最大分别增加了12.04%、9.36%、29.64%、12.63%,经济效益最大增加65.08%。较短年限内以生物有机肥氮替代8%或以牛、羊粪氮替代16%化肥氮是此研究推荐的施肥方案。     

Alleviation of drought stress in maize (Zea mays L.) by using endogenous endophyte Bacillus subtilis in North West Himalayas

ABSTRACT

In the present study, we reported the isolation and molecular characterisation of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-producing endophyte and its effect on alleviating drought stress in maize. Ten morphologically distinct indigenous plant growth-promoting rhizobacteria (PGPR) from maize roots and rhizosphere were screened for multiple plant growth-promoting (PGP) traits, and of ten, two strains (DHK and B1N1) possessing maximum PGP traits were evaluated at three water stress regimes in maize: (i) 80% field capacity (FC), (ii) 60% FC, and (iii) 40% FC for 45 days, starting 15 days after sowing to the maturity. Inoculation of DHK strain with maize at 80% FC induced a significant increase in plant biomass (root biomass, 86.67%; shoot biomass, 111.63%) together with decreased reactive oxygen species and increased activity of antioxidant enzymes (superoxide dismutase, 14.11?U/g fresh weight; peroxidase, 1.14?U/g fresh weight and catalase; 14.91?U/g fresh weight) compared to uninoculated control at same water regime (80% FC). The derivative strain also significantly accrued nutrients in maize and enhanced total chlorophyll and amino acid content in comparison with non-inoculated plants. 16S rDNA analysis of DHK strain revealed its lineage to Bacillus subtilis. Present investigations demonstrated the potential of the bacterial partner in alleviating drought stress in maize.