Phosphorus starvation response dynamics and management in plants for sustainable agriculture

Phosphorus (P) is an essential macronutrient required for the survival and reproduction of all living organisms. Its inorganic form (Pi) is taken up by the roots to support plant growth and development, and its availability directly determines agricultural productivity. The primary source of P replenishment in agriculture is chemical phosphate (Pi) fertilizers. While application of Pi-fertilizers to croplands ensures high yield agriculture, its intensive use leads to several environmental implications, including loss of soil fertility and pollution of water bodies with runoff fertilizer. Global non-renewable P-reserves are finite and would last for only a few hundred years. Therefore, a holistic approach is needed to combine Pi-use efficient germplasm with the targeted fertilization, agronomically superior fertilizer formulations for better P-management. The latest technologies to reclaim Pi from alternative sources need to be explored. In the present review, we first outline the challenges and environmental consequences of Pi-intensive fertilization, followed by plants' response and adaptive strategies to Pi starvation. Next, we discuss the role of microbes and Pi-nanofertilizer to plant Pi nutrition. Finally, a few cutting-edge technologies and innovative solutions available for reclaiming Pi from waste are argued.

     

Potentials of termite mound soil bacteria in ecosystem engineering for sustainable agriculture

The environmental deteriorating effects arising from the misuse of pesticides and chemical fertilizers in agriculture has resulted in the pursuit of eco-friendly means of producing agricultural produce without compromising the safety of the environment. Thus, the purpose of this review is to assess the potential of bacteria in termite mound soil to serve as biofertilizer and biocontrol as a promising tool for sustainable agriculture. This review has been divided into four main sections: termite and termite mound soils, bacterial composition in termite mound soil, the role of bacteria in termite mound soil as biofertilizers, and the role of bacteria in termite mound soil as biocontrol. Some bacteria in termite mound soils have been isolated and characterized by various means, and these bacteria could improve the fertility of the soil and suppress soil borne plant pathogens through the production of antibiotics, nutrient fixation, and other means. These bacteria in termite mound soils could serve as a remarkable means of reducing the reliance on the usage of chemical fertilizers and pesticides in farming, thereby increasing crop yield.     

Breeding for abiotic stresses for sustainable agriculture

Using cereal crops as examples, we review the breeding for tolerance to the abiotic stresses of low nitrogen, drought, salinity and aluminium toxicity. All are already important abiotic stress factors that cause large and widespread yield reductions. Drought will increase in importance with climate change, the area of irrigated land that is salinized continues to increase, and the cost of inorganic N is set to rise. There is good potential for directly breeding for adaptation to low N while retaining an ability to respond to high N conditions. Breeding for drought and salinity tolerance have proven to be difficult, and the complex mechanisms of tolerance are reviewed. Marker-assisted selection for component traits of drought in rice and pearl millet and salinity tolerance in wheat has produced some positive results and the pyramiding of stable quantitative trait locuses controlling component traits may provide a solution. New genomic technologies promise to make progress for breeding tolerance to these two stresses through a more fundamental understanding of underlying processes and identification of the genes responsible. In wheat, there is a great potential of breeding genetic resistance for salinity and aluminium tolerance through the contributions of wild relatives.     

The role of conservation agriculture in sustainable agriculture

The paper focuses on conservation agriculture (CA), defined as minimal soil disturbance (no-till, NT) and permanent soil cover (mulch) combined with rotations, as a more sustainable cultivation system for the future. Cultivation and tillage play an important role in agriculture. The benefits of tillage in agriculture are explored before introducing conservation tillage (CT), a practice that was borne out of the American dust bowl of the 1930s. The paper then describes the benefits of CA, a suggested improvement on CT, where NT, mulch and rotations significantly improve soil properties and other biotic factors. The paper concludes that CA is a more sustainable and environmentally friendly management system for cultivating crops. Case studies from the rice-wheat areas of the Indo-Gangetic Plains of South Asia and the irrigated maize-wheat systems of Northwest Mexico are used to describe how CA practices have been used in these two environments to raise production sustainably and profitably. Benefits in terms of greenhouse gas emissions and their effect on global warming are also discussed. The paper concludes that agriculture in the next decade will have to sustainably produce more food from less land through more efficient use of natural resources and with minimal impact on the environment in order to meet growing population demands. Promoting and adopting CA management systems can help meet this goal.     

Advanced agricultural biotechnologies and sustainable agriculture

Agricultural biotechnologies are anchored to a scientific paradigm rooted in experimental biology, whereas sustainable agriculture rests on a biological paradigm that is best described as ecological. Both biotechnology and sustainable agriculture are associated with particular social science paradigms: biotechnology has its foundation in neoclassical economics, but sustainability is framed by an emerging community-centered, problem-solving perspective. Fundamentally, biotechnology and neoclassical economics are reductionist in nature. Sustainability and community problem-solving, however, are nonreductionist. Given these differences, we might see the development of two rather distinct systems of food production in the near future.     

Methylotrophic bacteria in sustainable agriculture

Excessive use of chemical fertilizers to increase production from available land has resulted in deterioration of soil quality. To prevent further soil deterioration, the use of methylotrophic bacteria that have the ability to colonize different habitats, including soil, sediment, water, and both epiphytes and endophytes as host plants, has been suggested for sustainable agriculture. Methylotrophic bacteria are known to play a significant role in the biogeochemical cycle in soil ecosystems, ultimately fortifying plants and sustaining agriculture. Methylotrophs also improve air quality by using volatile organic compounds such as dichloromethane, formaldehyde, methanol, and formic acid. Additionally, methylotrophs are involved in phosphorous, nitrogen, and carbon cycling and can help reduce global warming. In this review, different aspects of the interaction between methylotrophs and host plants are discussed, including the role of methylotrophs in phosphorus acquisition, nitrogen fixation, phytohormone production, iron chelation, and plant growth promotion, and co-inoculation of these bacteria as biofertilizers for viable agriculture practices.     

生态系统原理与可持续农业

论述了农业生态系统的能量流动物质循环原理、系统相关原理、相生相克原理、忍耐极限原理、结构功能原理、系统开放原理、限制因子原理、非加和原理、生物竞争原理和竞争排斥原理 ;认为中国生态农业是一种较为典型的可持续发展的农业系统类型 ,建议在国家持续农业发展进程中要积极推行生态农业 .     

Phosphorus and phosphate solubilizing bacteria: Keys for sustainable agriculture

Abstract

Phosphorus (P) is one of the most important minerals required for plant growth occupying a strong position among soil macro nutrients. Soil P deficiency is often fulfilled by phosphate fertilizers. P deficiency in soils is due to less total P contents in the soil and fixation of added P from chemical fertilizers as well as other organic sources like manures. The response of plant under P stress or even when it is present in adequate amount is very mild. The basic constraint in the availability of P is its solubilization as it gets fixed both in acidic and alkaline soil. Soil fixed P can only be solubilized by phosphate solubilizing microorganisms (PSMs).These bacteria released different types of organic acids in the soil which make P soluble and available to plants. The potential of these PSMs to solubilize P varies and mainly depends upon mechanism adopted for solubilization, their molecular genetics as well as their ability to release P in soil. The PSMs, having all the characteristics of phytohormone production, nitrogen fixation, as well as, heavy metal decontamination and creating salt stress tolerance in plants, are quite rare for sustainable agriculture. Application of this environment friendly approach for increasing crop productivity as well as its impact on soil and plant health is discussed in this review which will not only open new avenues of research but also provide fruitful information about phosphate solubilizing microbes for sustainable agriculture development.     

Creating future crops: a revolution for sustainable agriculture

正Despite the remarkable increase in food supply over the past halfcentury, global food security is facing unprecedented challenges as a result of a blooming human population, a shortage of arable land, and the significant threat posed by climate change (Bailey-Serres et al.,2019; Tian et al., 2020). Current crop production strategies are insufficient to nourish the world population. To ensure food security and the development of sustainable abuilding to explore emerging strategies and design novel crops with high productivity and efficiency, which are also more resilient to climate variability and natural disasters.     

Cyanobacteria as a source of biofertilizers for sustainable agriculture

Continuous increase in global human population and depletion of natural resources of energy posing threat to environment needs, sustainable supply of food and energy. The most ecofriendly approach ‘green technology’ has been exploited for biofertilizer preparation. Cyanobacteria are the most successful and sustained prokaryotic organism during the course of evolution. They are considered as one of the primitive life forms found on our planet. Cyanobacteria are emerging candidates for efficiently conversion of radiant energy into chemical energy. This biological system produces oxygen as a by-product. Cyanobacterial biomass can also be used for the large scale production of food, energy, biofertilizers, secondary metabolites, cosmetics and medicines. Therefore, cyanobacteria are used in ecofriendly sustainable agricultural practice for production of biomass of very high value and decreasing the level of CO_2. This review article describes the methods of mass production of cyanobacterial biofertilizers and their applications in agriculture and industrial level.     

Biological nitrogen fixation for sustainable agriculture: A perspective

The economic and environmental costs of the heavy use of chemical N fertilizers in agriculture are a global concern. Sustainability considerations mandate that alternatives to N fertilizers must be urgently sought. Biological nitrogen fixation (BNF), a microbiological process which converts atmospheric nitrogen into a plant-usable form, offers this alternative. Nitrogen-fixing systems offer an economically attractive and ecologically sound means of reducing external inputs and improving internal resources. Symbiotic systems such as that of legumes and Rhizobium can be a major source of N in most cropping systems and that of Azolla and Anabaena can be of particular value to flooded rice crop. Nitrogen fixation by associative and free-living microorganisms can also be important. However, scientific and socio-cultural constraints limit the utilization of BNF systems in agriculture. While several environmental factors that affect BNF have been studied, uncertainties still remain on how organisms respond to a given situation. In the case of legumes, ecological models that predict the likelihood and the magnitude of response to rhizobial inoculation are now becoming available. Molecular biology has made it possible to introduce choice attributes into nitrogen-fixing organisms but limited knowledge on how they interact with the environment makes it difficult to tailor organisms to order. The difficulty in detecting introduced organisms in the field is still a major obstacle to assessing the success or failure of inoculation. Production-level problems and socio-cultural factors also limit the integration of BNF systems into actual farming situations. Maximum benefit can be realized only through analysis and resolution of major constraints to BNF performance in the field and adoption and use of the technology by farmers.     

Soil nitrogen balance assessment and its application for sustainable agriculture and environment

Soil nitrogen balance assessment (SNBA) serves as an effective tool for estimating the magnitude of nitrogen loss/gain of the agro-eco systems and to appraise their sustainability. SNBA brings forth awareness of soil fertility problems, besides providing information relating to the resultant release of nitrogen into the environment consequent to agricultural practices. Quantitative information relating to nitrogen escape into the environment through such exercises can be gainfully utilized for identification of causative factors, enhancing fertilizer use efficiency and formulating programmes aimed at plugging N leakages. An overview of nitrogen balance approaches and methodologies is presented. A deeper understanding and insight into the agro-eco systems provided by the SNBA exercises can lay the basis for the formulation of effective agronomic interventions and policies aimed at promoting sustainable agriculture and a benign environment.     

Soil nitrogen balance assessment and its application for sustainable agriculture and environment

Soil nitrogen balance assessment (SNBA) serves as an effective tool for estimating the magnitude of nitrogen loss/gain of the agro-eco systems and to appraise their sustainability. SNBA brings forth awareness of soil fertility problems, besides providing information relating to the resultant release of nitrogen into the environment consequent to agricultural practices. Quantitative information relating to nitrogen escape into the environment through such exercises can be gainfully utilized for identification of causative factors, enhancing fertilizer use efficiency and formulating programmes aimed at plugging N leakages. An overview of nitrogen balance approaches and methodologies is presented. A deeper understanding and insight into the agro-eco systems provided by the SNBA exercises can lay the basis for the formulation of effective agronomic interventions and policies aimed at promoting sustainable agriculture and a benign environment.