Under filed conditions,mycorrhizal inoculum effectiveness depends on plant species and phosphorus nutrition

Abstract

The cultivation of horticultural crops, such as green peppers, tomatoes, eggplants and bell peppers is very common in semi-arid Mediterranean climate conditions. Two field experiments were performed to determine the effect of mycorrhizal species, plant species and phosphorus levels on mycorrhizal effectiveness and phosphorus (P) and zinc (Zn) nutrient uptake. In the first experiment, under field conditions, four plants species were inoculated with five arbuscular mycorrhizae (AM) species. In the second field experiment, under the same soil conditions, the same plant species were treated with three levels of phosphorus (P), i.e., control; 50?kg and 100?kg P₂O₅ ha^?1. The most effective mycorrhiza species Claroideoglomus etunicatum selected in the first experiment was used in the second field first experiment. In the first experiment, fruit yield enhancement, yield increase, inoculation effectiveness and nutrient concentration in the plant leaves were analyzed. Under field conditions, plant species growth is strongly dependent on the species of AM fungi. Tomato and green pepper plants were inoculated with Cl. etunicatum, eggplants were inoculated with Funneliformis mosseae and bell peppers were inoculated with Rhizophagus clarus, which are high fruit-yielding plant species. In general, Fu. mosseae and Cl. etunicatum increased the yield of the tomatoes, green peppers and eggplants. It seems mycorrhiza species specific to plant species. In the second experiment, mycorrhizal inoculation with P fertilizer application, in particular a moderate amount of P (50?kg ha^?1 P₂O₅) fertilizer increased the green pepper, bell pepper and tomato fruit yield compared with non-inoculated plants and non-P fertilizer application treatments. Increasing the application of P level reduced the mycorrhizal inoculation effectiveness (MIE). The results indicate that for all four solanaceae family plants 50?kg ha^?1 P₂O₅ is a P level threshold for mycorrhizal development, which enhanced plant growth and addition of fertilizer over 50?kg ha^?1 P₂O₅ reduced MIE. P and Zn uptake were significantly increased with mycorrhizal inoculation. These findings are supported by our hypothesis that mycorrhiza inoculation can reduce mycorrhizal dependent horticultural plants P fertilizer requirement.     

Rhizobium and phosphorus influence on lentil seed protein and lipid

Root nodulation by rhizobial bacteria and P fertilization may affect seed protein and lipid composition in plants by altering nitrogen (N) and phosphorus (P) nutrition or by eliciting metabolic responses by the host plant. This study was conducted to determine the effects of rhizobium and P fertilization on seed protein and lipid contents and yield of lentil (Lens culinaris Medik). Lentil was grown to maturity in a greenhouse with P levels of 0 (low) and 50 (high) mg kg^‐1 soil with or without inoculation with Rhizobium bacteria. At the low level of P, protein and lipid concentrations and protein contents were significantly higher in inoculated than in uninoculated plants. Seed dry weight and protein concentrations and contents were higher in inoculated than in uninoculated plants at the high level of P. Seed protein/lipid (Pro/L) concentration ratios varied between inoculated and uninoculated plants at both P levels, and was related to the intensity of root nodulation. Lipid and protein contents were highly correlated with P content in lentil seeds. Seed lipid and protein contents were lower at the high level of P in uninoculated than inoculated plants. The data indicate different patterns of seed P accumulation and different relationships between seed P content and protein and lipid contents in inoculated and uninoculated plants. This might indicate that the intensity of nodulation altered the response of seed protein and lipid metabolism to increasing P availability, which affected protein and lipid ratios.     

Effect of soil pH on plant growth and nodulation of cowpea

Abstract

A study was conducted to evaluate the effect of soil pH on rhizobium inoculation, plant growth and nodulation of cowpea (Vigna unguiculata). Both inoculated and non‐inoculated seeds of the cultivar ‘California Blackeye No. 5’ were grown in the greenhouse in plastic pots with growth medium being a Norfolk sandy loam (Fine, loamy siliceous, thermic, Typic Palendult) soil under different pH levels. Both soil pH and rhizobium inoculation significantly affected root length, plant height, nodule and pod number per plant. Within the pH range of 6.6 to 7.6, these growth parameters generally were at their maximum, decreasing above or below this pH range. Non‐inoculated plants produced some nodules, indicating failure of the methyl bromide to totally destroy all residual soil rhizobta before inoculation treatment.

The inoculated plants produced more seeds and the increased number of nodules of treated plants was directly related to increased seed weight. Since nodule number was highest at the approximate pH range of 6.6 to 7.6, this range was considered optimum for nodulation of cowpea by this strain of rhizobium under greenhouse conditions. At pH 7.5 and above, roots tended to be more fibrous and nodules were generally smaller in size.     

Discrimination between Japanese and Chinese Products using trace elements concentration of kernel in pickled Japanese apricot

pp. 881–889
In order to understand the influences of nitrogen and silicate fertilizer application on anther length and percentage of the sterility of the rice plant, we investigated by field experiment in Hokkaido Kamikawa Agric. Exp. Stn. (Brown Lowland soil) and by air-conditioned room experiment.
  The results are summarized as follows.
1) Application of silicate fertilizer decreased percentage of sterility. Compared with basal application, topdressing of silicate fertilizer was more effective in increasing carbohydrate content and anther length, decreasing percentage of sterility.
2) The anther length was negatively correlated to percentage of sterility and was positively correlated to carbohydrate content in the rice plant. Similar regression curves were plotted between the field experiment and the air-conditioned room experiment.
3) Silicate content in rice plants was increased at the flag leaf stage by applying both basal and topdressing silicate fertilizer. Furthermore, silicate content was correlated to carbohydrate content. Nitrogen content was negatively correlated to carbohydrate content.
4) Protein content in polished rice was decreased by silicate fertilizer application.     

解磷细菌、磷酸岩和化肥对玉米和小麦轮作及其经济收入的影响

A two-year field study was conducted to test the effects of two phosphate-solubilizing bacteria (PSB), Pantoea cypripedii (PSB-3) and Pseudomonas plecoglossicida (PSB-5), inoculated singly or together with rock phosphate (RP) fertilization on maize and wheat cropping cycle by comparing with chemical P fertilizer (diammonium phosphate, DAP), mainly in the crop yield, soil fertility and economic returns. Inoculation of PSB together with RP fertilization increased the crop growth in terms of shoot height, shoot and root dry biomass, grain yield and total P uptake in both maize and wheat crops compared to the other treatments. Soil fertility in the context of available P, enzyme activities and PSB population in both maize and wheat crops was significantly improved with PSB inoculation together with RP fertilization compared to DAP treatment. The combined use of PSB inoculation and RP fertilization was more economical due to minimal cost and maximum returns. These results suggested that PSB inoculation along with RP fertilization would be an appropriate substitute for chemical phosphate fertilizer application in sustainable agriculture systems.     

有机肥、化肥及接种微生物对甜玉米生理和生长的影响

A pot culture experiment was carried out in a glasshouse to compare the physiology and growth of sweet corn plants(Zea mays L.cv,Honey Bantam) grown under orgainc and chemical fertilizations with or without microbial inoculation(MI).The organic fertilizer used was fermented mainly using rice bran and oil mill sludge,and the MI was a liquid product containing many eneficial microbes such as lactic acid bacteria,yeast,photosynthetic bacteria and actinomycetes.The application amounts of the organic fertilizer and chemical fertilizers were based on the same rate of nitrogen,phosphorus and potassium.Sweet corn plants fertilized with organic materials inoculated with beneficial microbes grew better than those without inoculation.There were no significant differences in physiology and growth of the sweet corn plants between treatments of chemical fertilizers with and without MI.Among the organic fertilization treatments.only the sweet corn plants with organic fertilizer and MI applied 4 weeks before sowing had simlilar photosyntheitic capacity,total dry matter yield and ear yield to those with chemical fertilizers.Sweet corn plants in other organic fertilization treatments were weaker in physiology and grown than those in chemical fertilization treatments.There was no significant variance among chemical fertilization treatments at differenct time.It is concluded form this research that this organic fertilizer would be more effective if it was inoculated with the beneficial microbes.Early application of the organic fertilizer with beneficial microbes before sowing was recommended to make the nutrients available before the rapid growth at the eraly stage and obtain a yield simlar to or higher than that with chemical fertilizations.     

The effect of nitrogen and silica nutrition on percentage of sterility by rice plant

pp. 881–889

In order to understand the influences of nitrogen and silicate fertilizer application on anther length and percentage of the sterility of the rice plant, we investigated by field experiment in Hokkaido Kamikawa Agric. Exp. Stn. (Brown Lowland soil) and by air-conditioned room experiment.

The results are summarized as follows.

1) Application of silicate fertilizer decreased percentage of sterility. Compared with basal application, topdressing of silicate fertilizer was more effective in increasing carbohydrate content and anther length, decreasing percentage of sterility.

2) The anther length was negatively correlated to percentage of sterility and was positively correlated to carbohydrate content in the rice plant. Similar regression curves were plotted between the field experiment and the air-conditioned room experiment.

3) Silicate content in rice plants was increased at the flag leaf stage by applying both basal and topdressing silicate fertilizer. Furthermore, silicate content was correlated to carbohydrate content. Nitrogen content was negatively correlated to carbohydrate content.

4) Protein content in polished rice was decreased by silicate fertilizer application.     

Improvement of wheat and maize crops by inoculating Aspergillus spp. in alkaline soil fertilized with rock phosphate

Aspergillus tubingensis and A. niger were isolated from the landfills of rock phosphate mines and tested for their efficacy to solubilize rock phosphate (RP), and improve plant growth and phosphate (P) uptake by plants grown in soil amended with RP. The results showed that they effectively solubilized RP in Pikovskaya's (PKV) liquid medium and released significantly higher amounts of P into the medium. A. tubingensis solubilized and released 380.8 μg P mL^?1, A. niger showed better efficiency and produced 403.8 μg P mL^?1. Field experiments with two consecutive crops in alkaline agricultural soil showed that inoculation of these fungi along with RP fertilization significantly increased yield and nutrient uptake of wheat and maize plants compared with control soil. P uptake by wheat and maize plants and the available P increased significantly in the RP-amended soil inoculated with fungi compared with control. These results suggest that the fertilizer value of RP can be increased, especially in alkaline soils, by inoculating P-solubilizing fungi.     

Increase of secondary metabolite content in marigold by inoculation with plant growth-promoting rhizobacteria

The effects of single inoculation and co-inoculation of two plant growth-promoting rhizobacteria (PGPR) (Pseudomonas fluorescens, Azospirillum brasilense) on growth and essential oil (EO) composition and phenolic content were evaluated in marigold (Tagetes minuta). Plant growth parameters (shoot fresh weight, root dry weight, leaf number, node number) were measured. EO yield increased 70% in P. fluorescens-inoculated and co-inoculated plants in comparison with control (non-inoculated) plants, without altering EO composition. The biosynthesis of the major EO components was increased in the inoculated plants. Shoot fresh weight and EO yield were significantly higher in P. fluorescens-inoculated and in co-inoculated plants than in control plants. The total phenolic content was 2-fold higher in singly-inoculated or co-inoculated treatments than in controls. In view of the economic importance of monoterpenes and phenolic compounds for a variety of applications in the food and cosmetic industries, P. fluorescens and other PGPR have clear potential for improving the productivity of cultivated aromatic plants. Better understanding of the processes that affect the accumulation of secondary metabolites will lead to increased yields of these commercially valuable natural products.     

膜下滴灌花生适宜追肥时期和次数研究

[目的]为建立节水省肥高效花生栽培技术体系,本文研究了膜下滴灌追肥时期和次数对花生生长发育和产量的影响,明确膜下滴灌条件下花生高产栽培适宜的追肥时期和次数,探究出适用于花生生产的高效水肥一体化管理方式。[方法]于2017年在青岛农业大学胶州现代科技示范园,以花生品种青花7号为试材,进行了一垄双行膜下滴灌施肥田间试验。以不灌水不追肥为对照(CK),在花生生育期间施肥总量相同的前提下,设置7种追肥方式,分别为:花针期追施1次肥(N),结荚期追施1次肥(P),饱果期追施1次肥(F),花针期和结荚期分别追施1次肥(NP),花针期和饱果期分别追施1次肥(NF),结荚期和饱果期分别追施1次肥(PF),花针期、结荚期和饱果期分别追施1次肥(NPF),共8个处理。分别于花针期施肥前1天和施肥后12天、结荚期施肥前1天和施肥后12天、饱果期施肥前1天和施肥后12天、收获期取样,调查入土果针数和未入土果针数、单株荚果数。在收获期测定荚果产量、百果重、百仁重、荚果数、籽仁重、出仁率。[结果]就追肥时期而言,追肥效果为花针期>结荚期>饱果期;就追肥次数而言,2~3次追肥效果优于1次追肥。花生生育期间只追肥1次的情况下,以花针期追肥增产幅度最高,结荚期追肥次之,饱果期追肥最低,分别较对照增产18%、15%和8%;花生生育期间追肥2次,则以花针期和结荚期追肥增产幅度最高,花针期和饱果期追肥次之,结荚期和饱果期追肥最低,分别较对照增产38%、24%和20%;花生生育期间追肥3次(花针期、结荚期和饱果期),较对照增产27%。各处理比对照花生百果重分别增加5%、6%、7%、15%、11%、11%、15%;百仁重分别增加1%、3%、2%、5%、5%、6%和7%;荚果数分别提高23%、21%、17%、51%、30%、36%和49%;籽仁重分别提高14%、21%、18%、43%、23%、27%和30%;出仁率分别提高5%、2%、2%、5%、3%、3%和5%。[结论]在本试验条件下,追肥时期越早、前期追肥量越大越有利于促进花生果针的形成、入土和结果。综合考虑滴灌追肥成本及效益,花生生育期内追肥2次,即在花针期和结荚期追肥对花生生长和产量表现最优,可作为花生水肥一体高效施肥管理措施。     

Effect of Arbuscular Mycorrhizal Fungi and Phosphate-Solubilizing Bacteria Consortia Associated with Phospho-Compost on Phosphorus Solubilization and Growth of Tomato Seedlings (Solanum lycopersicum L.)

ABSTRACT

The exploitation of phosphate mines generates an important quantity of phosphate sludge that remains accumulated and not valorized. In this context, composting with organic matter and rhizospheric microorganisms offers an interesting alternative and that is more sustainable for agriculture. This work aims to investigate the synergetic effect of arbuscular mycorrhizal fungi (AMF), phosphate-solubilizing bacteria (PSB) and phospho-compost (PC), produced from phosphate-laundered sludge and organic wastes, and their combination on plant growth, phosphorus solubilization and phosphatase activities (alkaline and acid). Inoculated mycorrhizae and bacteria strains used in this study were selected from plant rhizosphere grown on phosphate-laundered sludge. Significant (p < .05) increases in plant growth was observed when inoculated with both consortia and PC (PC+ PSB+ AMF) similar to those recorded in plants amended with chemical fertilizer. Tripartite inoculated tomato had a significantly (p < .05) higher shoot height; shoot and root dry weight, root colonization and available P content, than the control. Co-inoculation with PC and AMF greatly increased alkaline phosphatase activity and the rate of mycorrhizal intensity. We conclude that PC and endophytic AMF and PSB consortia contribute to a tripartite inoculation in tomato seedlings and are coordinately involved in plant growth and phosphorus solubilization. These results open up promising prospects for using formulate phospho-compost enriched with phosphorus-solubilizing microorganisms (PSM) in crop cultivation as biofertilizers to solve problems of phosphate-laundered sludge accumulation.     

Cultivar selection as a tool for managing soil phosphorus and faba bean yield ‎sustainability

ABSTRACT

A sustainable agricultural tactics for countering a possible phosphate shrinking should comprise the releasing of legacy soil phosphorus (P), in parallel to lowering P fertilizer load, and increasing the use of recycled P sources with economic crop yield in mind. Therefore, a field trail was conducted to estimate the possibility of choosing the appropriate cultivar as a tool to raise the use efficiency of reserved soil P. Herein, three faba bean cultivars (Sakha-3, Nubaria-1 and Giza-843) were evaluated under five applications of P fertilizer (rock phosphate, super phosphate, Bacillus megaterium, rock phosphate+B. megaterium, and super phosphate+B. megaterium). Findings showed that the lowest value of estimated available P in soil after harvest was obtained from plots sown by Sakha-3 plants and fertilized with super phosphate+B. megaterium. Plots sown with Nubaria-1 and fertilized by rock phosphate+B. megaterium or B. megaterium (for weight of 100 seeds and seed yield) in addition to super phosphate+B. megaterium (for seed yield) produced the maximum increases. The highest P recovery efficiency was achieved with Nubaria-1 inoculated by B. megaterium alone. In conclusion, super phosphate+B. megaterium × Nubaria-1 achieve maximum crop returns and secure high short-term recovery of applied P.     

Inoculation of tomato plants with selected PGPR represents a feasible alternative to chemical fertilization under salt stress

Plant growth‐promoting rhizobacteria (PGPR) are soil bacteria that colonize the rhizosphere of plants, enhance plant growth, and may alleviate environmental stress, thus constituting a powerful tool in sustainable agriculture. Here, we compared the capacity of chemical fertilization to selected PGPR strains to promote growth and alleviate salinity stress in tomato plants (Solanum lycopersicum L.). A pot experiment was designed with two main factors: fertilization (chemical fertilization, bacterial inoculation with seven PGPR, or a non‐fertilized non‐inoculated control) and salt stress (0 or 100 mM NaCl). In the absence of stress, a clear promotion of growth, a positive effect on plant physiology (elevated F_v/F_m), and enhanced N, P, and K concentrations were observed in inoculated plants compared to non‐fertilized controls. Salinity negatively affected most variables analyzed, but inoculation with certain strains reduced some of the negative effects on growth parameters and plant physiology (water loss and K⁺ depletion) in a moderate but significant manner. Chemical fertilization clearly exceeded the positive effects of inoculation under non‐stressed conditions, but conversely, biofertilization with some strains outperformed chemical fertilization under salt stress. The results point at inoculation with selected PGPR as a viable economical and environment‐friendly alternative to chemical fertilization in salinity‐affected soils.     

Effective Nutrient Sources for Plant Growth on Bauxite Residue: II. Evaluating the Response to Inorganic Fertilizers

An integral part of managing dust emissions from bauxite residue storage areas in Western Australia is the establishment of native vegetation and dust control crops. Recent changes to local health department regulations preclude the routine use of poultry manure, the previous standard fertilizer for growing dust control crops on bauxite residue sand. This paper reports on a field evaluation of different forms of inorganic fertilizer, to assess their effectiveness as alternatives to poultry manure for supplying nutrients to dust control crops. We compared plant growth and nutrient uptake under different forms of nitrogen (N) and phosphorus (P) fertilizers with additional potassium (K) and trace elements. A diammonium phosphate (DAP) based fertilizer blend which supplied 270 kg N ha^?1 of N and 307.5 kg P ha^?1 was found to be more effective than a superphosphate based blend containing the same amounts of these nutrients. The DAP treatment did not respond to topdressing with different N fertilizers, but plant growth in the superphosphate treatment was responsive to topdressing with N. Of the three different nitrogenous fertilizers evaluated for topdressing the superphosphate treatment (ammonium sulphate, diammonium phosphate, and urea), the ammonium based fertilizers were most effective. The DAP blend was the most cost effective of all the fertilizers studied, costing only A$1070 ha^?1 compared with A$2473 ha^?1 for the superphosphate blend and A$1600 ha^?1 for poultry manure. We concluded that the DAP fertilizer blend could be used as an effective replacement for poultry manure for growing dust control crops on bauxite residue sand.     

Mycorrhizae enhances horticultural plant yield and nutrient uptake under phosphorus deficient field soil condition

Mycorrhizae can enhance plant growth and phosphorus (P) use efficiency in horticultural plants. This research evaluated the effectiveness of mycorrhizae on increasing growth and yield of nine horticultural plants for two different rates of P fertilization under field conditions. The mycorrhizal inoculums increased the root colonization of mycorrhizal horticultural plants compared with the non-inoculated treatments. Mycorrhizal inoculation significantly increased onion, garlic, chickpea, broad bean, carrot, parsley and cress plants. Mycorrhizal effectiveness showed that without P addition the effect of mycorrhizae on plant yield is much higher than that with P fertilizer addition. Under low P fertilization inoculation effectiveness is much higher than P addition treatments. Mycorrhizal inoculums also increased tissue P and zinc (Zn) for horticultural plant. The improved growth, yield, Zn and P uptake in plants demonstrated the potential of mycorrhizal inoculation to reduce the effects P fertilization on horticultural plants grown under field conditions.     

Growth response of field-grown Siratro (Macroptilium atropurpureum Urb.) and Aeschynomene american L. to inoculation with selected vesicular-arbuscular mycorrhizal fungi

Summary The effect of inoculation with a selected isolate of Glomus etunicatum Becker and Gerdemann and one of G. intraradices Schenck and Smith on the growth and nutrient content of Macroptilium atropurpureum Urb. cv. Siratro and Aeschynomene americana L., at applied P levels of 10, 30, 60, and 120 kg ha^-1, was studied under field conditions. At all P levels and for all harvests, the shoot dry mass of Siratro and A. americana were greater for the plants inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungi than the control plants. Differences between the VAM fungus-inoculated and the control plants were most marked between 30 and 90 kg ha^-1 of applied P and diminished at 120 kg ha^-1. At the first harvest of Siratro, the plants inoculated with G. etunicatum had a greater shoot dry mass than those inoculated with G. intraradices, for all levels of applied P. However, for subsequent harvest of Siratro and for the one harvest of A. americana the response of shoot dry mass to the two VAM fungi was equivocal. Fungal inoculation gave at least a 30% saving in the amount of P fertilizer required (40 kg ha^-1) for the maximum yield. The plants inoculated with VAM fungi had a greater tissue concentration and total content of P and N than the control plants at low and intermediate levels of applied P. The percentage of root colonized by VAM fungi for the inoculated plants of the two legumes increased linearly with P additions up to 60 kg ha^-1. The conclusion is that under amended (limed and fertilized) soil conditions, inoculation with selected VAM fungi can improve the establishement and growth of forage legumes in fields that contain ineffective populations of native VAM fungi.     

石灰性土壤难溶态磷的微生物转化和利用

目前农业生产中大多通过施用可溶性磷肥为植物提供有效磷。磷酸根化学性质活泼,施入土壤后能很快与土壤中的其它成分发生反应,使植物对其利用的有效度随时间延长而降低,最终以难溶性磷酸盐或吸附态形式滞留于土壤中,难以被植物直接吸收。据估计,在石灰性土壤中约有80% 的磷肥以难溶性磷酸盐存在。为此人们采用了许多方法提高磷肥的利用率,其中利用植物根际与磷循环相关的生物学系统来调节植物根际磷的有效性是重要的途径之一。这个生物学系统包括植物本身对土壤难溶态磷的吸收与利用以及土壤中某些微生物参与的难溶态磷的释放与利用。本文论述了微生物( 细菌和真菌) 转化和利用石灰性土壤中难溶态磷的研究进展。     

Effect of mineral fertilizer,pig manure,and <Emphasis Type="Italic">Azospirillum rugosum</Emphasis> on growth and nutrient contents of <Emphasis Type="Italic">Lactuca sativa</Emphasis> L.

Benefits from the application of plant growth-promoting bacteria in agriculture largely depend on the complex interactions between several factors including the nature of fertilizers selected. This study was designed to determine the fine tuning between the inoculated bacteria and different fertilizers and their effect on the growth of lettuce plants (Lactuca sativa L.). Plant growth promotion by a novel species of the genus Azospirillum, namely A. rugosum IMMIB AFH-6, was tested by biochemical, bioassay, and greenhouse studies. The treatments used in the greenhouse study were; unfertilized control (Blank), half recommended dose of chemical fertilizer (1/2CF), full recommended dose of chemical fertilizer (1CF), pig manure fertilizer (PMF), pig manure fertilizer + half recommended dose of chemical fertilizer (PMF + 1/2CF), and pig manure fertilizer + full recommended dose of chemical fertilizer (PMF + 1CF). All these treatments when inoculated with A. rugosum IMMIB AFH-6 inoculation were, respectively, In-Blank, In-1/2CF, In-1CF, In-PMF, In-PMF + 1/2CF, and In-PMF + 1CF. Significant increase in plant biomass and shoot N, P, Ca, and Fe was shown in the In-Blank treatment. Plant growth in soil amended with PMF and A. rugosum IMMIB AFH-6 was significantly lower than in soil treated with the chemical fertilizer, but inoculation combined with chemical fertilizer significantly elevated the plant biomass. The In-PMF + 1/2CF treatment showed the highest yield. A. rugosum IMMIB AFH-6 facilitated the accumulation of trace minerals in higher concentrations when PMF was combined with 1CF. To examine the benefits of inoculation by A. rugosum IMMIB AFH-6, we have proposed a new type of data analysis which considers both biomass and nutrient content of plants. This new type of analysis has shown the importance of the mineral content of plant.     

应用~(15)N研究氮肥运筹对棉花氮素吸收利用及产量的影响

【目的】有关棉花适宜的施氮时期存在争议,国外有学者推荐最佳施氮时期为出苗后和现蕾期,也有研究认为播前和初花期各施一半较好。氮同位素示踪技术能区分作物吸收利用的肥料氮及土壤氮,并能深入细致研究施入氮肥的去向及在作物体内的分配。本文采用氮同位素示踪技术研究氮肥底追比例,施氮时期对棉花氮素吸收和产量的影响,以期为华北平原棉区氮肥管理提供理论依据。【方法】采用盆栽试验,以转Bt+Cp TI基因抗虫棉品种中棉所79(CCRI 79)、中棉所60(CCRI 60)为材料,设氮肥底施与初花期追施比例1∶1(N1)、1∶2(N2)、0∶1(N3)、氮肥底施与蕾期追施比例0∶1(N4)4个处理,研究氮肥运筹对棉花初花期、收获期15N吸收、15N回收率、生物量积累和籽棉产量的影响。【结果】初花期棉株不同器官的氮素吸收来自氮肥(Ndff)的比例随底肥氮施用量的增加而显著增加,增幅为25.88%42.45%。收获期不同处理棉花单株Ndff%随追施氮量的增加而显著增加,增幅为26.92%54.14%,N3、N4处理的棉花单株Ndff%显著高于N1和N2。N2处理的棉花单株籽棉产量高于其他处理,但与N1处理的差异不显著,N2处理单株生物量与N1、N3差异不显著。2个品种N3、N4处理的棉花收获期单株15N积累量均显著高于N1和N2处理,棉株收获期15N回收率均显著高于N1。N2处理的棉花收获期15N回收率高于N1处理,但差异未达到显著水平。棉花收获后N2处理土壤15N回收率低于N1,但差异不显著。【结论】本试验条件下,2个棉花品种氮素底追比为1∶2时的籽棉产量与15N回收率优于底追比为1∶1处理,底追比为0∶1的处理15N回收率在4个处理中最高,但未显示出产量优势,这些结果有待在大田试验中进一步验证。     

Uptake and metabolism of nitrate in mycorrhizal plants as affected by water availability and N concentration in soil

We compare the effect of arbuscular mycorrhizal (AM) colonization and PO₄^?3 fertilization on nitrate assimilation, plant growth and proline content in lettuce plants growing under well‐watered (?0.04 MPa) or drought (?0.17 MPa) conditions. We also tested how AM‐colonization and PO₄^?3 fertilization influenced N uptake (¹⁵N) and the percentage of N derived from the fertilizer (% NdfF) by plants under a concentration gradient of N in soil. Growth of mycorrhizal plants was comparable with that of P‐fertilized plants only under well‐watered conditions. Shoot nitrogen content, proline and nitrate reductase activity were greater in AM than in P‐fertilized plants under drought. The addition of 100 μg g^?1 P to the soil did not replace the AM effect under drought. Under well‐watered conditions, AM plants showed similar (at 3 mmol N), greater (at 6 mmol N) or lesser (at 9 mmol N) %NdfF than P‐fertilized plants. Comparing a control (without AM inoculation) to AM plants, differences in % NdfF ranged from 138% (3 mmol N) to 22.6% (6 mmol N) whereas no differences were found at 9 mmol N. In comparison with P fertilization, mycorrhizal effects on %NdfF were only evident at the lowest N levels, which indicated a regulatory mechanism for N uptake in AM plants affected by N availability in the soil. At the highest N level, P‐fertilized plants showed the greatest %NdfF. In conclusion, AM symbiosis is important for N acquisition and N fertilizer utilization but this beneficial mycorrhizal effect on N nutrition is reduced under large quantities of N fertilizer.