逆境胁迫下的农业管理中土壤-植物-微生物相互作用研究进展

The expected rise in temperature and decreased precipitation owing to climate change and unabated anthropogenic activities add complexity and uncertainty to agro-industry.The impact of soil nutrient imbalance,mismanaged use of chemicals,high temperature,flood or drought,soil salinity,and heavy metal pollutions,with regard to food security,is increasingly being explored worldwide.This review describes the role of soil-plant-microbe interactions along with organic manure in solving stressed agriculture problems.Beneficial microbes associated with plants are known to stimulate plant growth and enhance plant resistance to biotic (diseases) and abiotic (salinity,drought,pollutions,etc.) stresses.The plant growth-promoting rhizobacteria (PGPR) and mycorrhizae,a key component of soil microbiota,could play vital roles in the maintenance of plant fitness and soil health under stressed environments.The application of organic manure as a soil conditioner to stressed soils along with suitable microbial strains could further enhance the plant-microbe associations and increase the crop yield.A combination of plant,stress-tolerant microbe,and organic amendment represents the tripartite association to offer a favourable environment to the proliferation of beneficial rhizosphere microbes that in turn enhance the plant growth performance in disturbed agro-ecosystem.Agriculture land use patterns with the proper exploitation of plant-microbe associations,with compatible beneficial microbial agents,could be one of the most effective strategies in the management of the concerned agriculture lands owing to climate change resilience.However,the association of such microbes with plants for stressed agriculture management still needs to be explored in greater depth.     

Lantana invasion: An overview

We review the key features of Lantana ( Lantana camara L.), an invasive plant species considered to be among the world's 10 worst weeds. Lantana occurs in diverse habitats and on a variety of soil types, and its spread is encouraged by animal activities and by human disturbances, such as cultivation, road construction, and changes in fire regimes. Lantana is morphologically distinct in the different regions of its invasive range compared to those regions in its native range. The biological attributes contributing to the success of Lantana as an invader species include: fitness homeostasis, phenotypic plasticity, dispersal benefits from destructive foraging activities, widespread geographic range, vegetative reproduction, fire tolerance, better competitive ability compared to native flora, and allelopathy. Mechanical, chemical and biological options for the eradication and control of Lantana are available. It is emphasized that ecosystem-level consequences of Lantana invasion, particularly on the biodiversity of native flora, are little understood and studies are needed to fulfill this knowledge gap.     

Co-inoculation of indigenous Pseudomonas oryzihabitans and Bradyrhizobium sp. modulates the growth, symbiotic efficacy, nutrient acquisition, and grain yield of soybean

Soil microbes play a vital role in improving plant growth, crop productivity, and soil health through solubilization of essential nutrients. Present investigation was conducted to access the efficacy of Bradyrhizobium sp. LSBR-3 and the indigenous phosphate-solubilizing Pseudomonas oryzihabitans LSE-3 in improving the symbiosis, nutrient accumulation, and yield of soybean. The isolate LSE-3, selected on the basis of phosphate solubilization, was screened for beneficial traits, antagonistic activities, and pathogenicity. The levels of indole acetic acid production (50.34 ±2.35 μg mL^-1), phosphate solubilization (184.4 ±7.4 mg L^-1), biofilm formation (optical density at 560 mm, 1.389 6 ±0.04), siderophore production (121.46 ±1.61 μg mL^-1), and 1-aminocyclopropane-1-carboxylate deaminase activity (0.51 ±0.07 mmol α-ketobutyrate μg^-1 protein h^-1) were significantly higher with the dual inoculants (LSBR-3 and LSE-3) than with the single inoculant LSBR-3. The plant growth-promoting traits of single and dual inoculants were evaluated for the synergistic effects on soybean under field conditions. Soybean plots treated with LSBR-3 + LSE-3 exhibited improvement in seed germination, plant height, plant biomass, and chlorophyll content compared with the uninoculated control. Dual inoculant treatments resulted in significantly higher symbiotic efficacy evidenced by increased nodulation (40.0 ±0.75 plant^-1), nodule biomass (188.52 ±6.29 mg plant^-1), and leghemoglobin content (11.02 ±0.83 mg g^-1 fresh nodule), and significantly increased activities of phosphatase (75.16 ±3.17 and 58.77 ±6.08 μg p-nitrophenol g^-1 h^-1 for alkaline and acid phosphatase, respectively) and dehydrogenase (32.66 ±1.92 μg triphenylformazan g^-1 h^-1) compared with the control. Dual inoculation with LSBR-3 and LSE-3 enhanced the uptake of macro- and micronutrients, reduced Na content in shoots, and resulted in 10.85% higher grain yield and ca. US$96.80 ha^-1 higher profit compared with the control. This is the first report on the effectiveness of combined inoculation of LSE-3 and LSBR-3 in promoting the growth, symbiotic efficacy, and yield of soybean for sustainable agriculture.     

Improving Rice-Based Cropping Pattern Through Soil Moisture and Integrated Nutrient Management in Mid-Tropical Plain Zone of Tripura,India

An experiment was conducted in three fallow paddy fields situated on the mid-tropical plain zone of a northeastern Indian state(Tripura) to provide rice fallow management options using leftover soil moisture and nutrients. The three experimental fields were managed by growing rice under the system of rice intensification as the rainy season crop and then groundnut, lentil, rapeseed and potato as the post-rainy season crops. Fertilization under the integrated nutrient management system and lifesaving irrigation at critical stages of each post-rainy season crop were provided. Results showed that the field water use efficiency values were 5.93, 2.39, 2.37 and 59.76 kg/(hm2·mm) and that the yield of these crops increased by approximately 20%, 34%, 40% and 20% after applying two lifesaving irrigations in groundnut, lentil, rapeseed and potato, respectively. Therefore, fallow paddy field can provide possible profitable crops during the post-rainy season by utilizing the residual moisture and minimum supplemental irrigation under improved nutrient management practices.     

印度热带森林干旱扰动土壤的微生物碳, 氮, 磷的研究

Variations in microbial biomass C (MB-C),N (MB-N) and P (MB-P) along a gradient of different dominant vegeta- tion covers (natural forest,mixed deciduous forest,disturbed savanna and grassland ecosystems) in dry tropical soils of Vindhyan Plateau,India were studied from January 2005 to December 2005.The water holding capacity,organic C,total N,total P and soil moisture content were comparatively higher in forest soils than in the savanna and grassland sites.Across different study sites the mean annual MB-C,MB-N and MB-P at 0-15 cm soil depth varied from 312.05 ± 4.22 to 653.40 ± 3.17,32.16 ± 6.25 to 75.66 ± 7.21 and 18.94 ± 2.94 to 30.83 ± 23.08 μg g ?1 dry soil,respectively.At all the investigated sites,the maximum MB-C,MB-N and MB-P occurred during the dry period (summer season) and the minimum in wet period (rainy season).In the present study,soil MB-C,MB-N and MB-P were higher at the forest sites compared to savanna and grassland sites.The differences in MB-C,MB-N and MB-P were significant (P 0.001) among sites and seasons.The MB-C (P 0.0001),MB-N (P 0.001) and MB-P (P 0.0001) were positively correlated with organic C,while the relationship between soil moisture and MB-C,MB-N and MB-P (P 0.001,P 0.01 and P 0.0001,respectively) was negative.The decreasing order of MB-C,MB-N and MB-P along study ecosystems was natural forest mixed deciduous forest savanna grassland.The results suggested that deforestation and land use practices (conversion of forest into savanna and grassland) caused the alterations in soil properties,which as a consequence,led to reduction in soil nutrients and MB-C,MB-N and MB-P in the soil of disturbed sites (grassland and savanna) compared to undisturbed forest ecosystems.     

Influence of Crop Nutrition on Grain Yield, Seed Quality and Water Productivity under Two Rice Cultivation Systems

The system of rice intensification (SRI) is reported to have advantages like lower seed requirement,less pest attack,shorter crop duration,higher water use efficiency and the ability to withstand higher degree of moisture stress than traditional method of rice cultivation.With this background,SRI was compared with traditional transplanting technique at Indian Agricultural Research Institute,New Delhi,India during two wet seasons (2009-2011).In the experiment laid out in a factorial randomized block design,two methods of rice cultivation [conventional transplanting (CT) and SRI] and two rice varieties (Pusa Basmati 1 and Pusa 44) were used under seven crop nutrition treatments,viz.T 1,120 kg/hm2 N,26.2 kg/hm2 P and 33 kg/hm2 K;T 2,20 t/hm2 farmyard manure (FYM);T 3,10 t/hm2 FYM+ 60 kg/hm2 N;T 4,5 t/hm2 FYM+ 90 kg/hm2 N;T 5,5 t/hm2 FYM+ 60 kg/hm2 N+ 1.5 kg/hm2 blue green algae (BGA);T 6,5 t/hm2 FYM+ 60 kg/hm2 N+ 1.0 t/hm2 Azolla,and T 7,N 0 P 0 K 0 (control,no NPK application) to study the effect on seed quality,yield and water use.In SRI,soil was kept at saturated moisture condition throughout vegetative phase and thin layer of water (2-3 cm) was maintained during the reproductive phase of rice,however,in CT,standing water was maintained in crop growing season.Results revealed that CT and SRI gave statistically at par grain yield but straw yield was significantly higher in CT as compared to SRI.Seed quality was superior in SRI as compared to CT.Integrated nutrient management (INM) resulted in higher plant height with longer leaves than chemical fertilizer alone in both the rice varieties.Grain yield attributes such as number of effective tillers per hill,panicle length and panicle weight of rice in both the varieties were significantly higher in INM as compared to chemical fertilizer alone.Grain yields of both the varieties were the highest in INM followed by the recommended doses of chemical fertilizer.The grain yield and its attributes of Pusa 44 were significantly higher than those of Pusa Basmati 1.The seed quality parameters like germination rate and vigor index as well as N uptake and soil organic carbon content were higher in INM than those in chemical fertilizer alone.CT rice used higher amount of water than SRI,with water saving of 37.6% to 34.5% in SRI.Significantly higher water productivity was recorded in SRI as compared to CT rice.     

Contribution of microbial phytases to the improvement of plant growth and nutrition: A review

Phytases belong to the class of phosphohydrolases that begin the step-wise hydrolysis of phosphates from phytates. Phytates are a derivative of myo-inositol, which is the primary storage form of organic phosphorus in plant cells. Phytase has been used globally to diminish phosphorus pollution and to enhance nutrition in monogastrics. In this review, the classification, sources, and diversity of microbial phytases, and their practical applications, as well as supplementation of the soil with transgenic and wild types of microbial strains, which can release phytase to enhance phosphorus availability for plant uptake and reduce the need for fertilizers, are discussed. The overexpressed microbial phytases in transgenic plants enhance the growth capacity of co-cultivated plants and can therefore be employed in agricultural and biotechnological practices, such as intercropping. The introduction of phytases into the soil for improved plant growth and enhanced crop yield can be accomplished without extra cost. A diverse group of photoautotrophic microalgae can synthesize phytase and will likely be useful in many human food and animal industries.     

Dynamics of the functional groups in the weed flora of dryland and irrigated agroecosystems in the Gangetic plains of India

The relative abundance of the weed functional types in dryland and irrigated rice in the Kharif (summer) crop field and dryland lentil and wheat in the irrigated Rabi (winter) crop field was studied at the agricultural farm of Banaras Hindu University, Varanasi, India. A total of 22 species, belonging to 17 families, was recorded in the dryland and irrigated rice ecosystems and 18 species, belonging to eight families, were recorded in the dryland lentil and irrigated wheat ecosystems. The Importance Value Index (IVI) of the hemicryptophytes showed an increasing trend with the crop growth period in the case of the dryland rice, whereas in the irrigated rice plots, a reduction in the IVI of the hemicryptophytes, with a related increase in the importance of the therophytes, was observed as the crop attained maturity. Also, the trend of a decreased IVI was observed for the geophytes in the fertilized dryland rice plots. The principal components analysis (PCA) ordination showed the uniqueness of the crop plot in terms of weed species composition. The PCA analysis of the functional types on the basis of the crop plots indicated that the hemicryptophyte and therophyte weed species composition was heavily altered at the initial and final sampling, although the weed flora was dominated by the therophytes and geophytes. These results suggest the prioritization of hierarchical temporal management options for the functional weed types in different crop plots and that this approach warrants further investigation.