Rhizobium as Biotechnological Tools for Green Solutions: An Environment-Friendly Approach for Sustainable Crop Production in the Modern Era of Climate Change.

Modern and industrialized agriculture enhanced farm output during the last few decades, but it became possible at the cost of agricultural sustainability. Industrialized agriculture focussed only on the increase in crop productivity and the technologies involved were supply-driven, where enough synthetic chemicals were applied and natural resources were overexploited with the erosion of genetic diversity and biodiversity. Nitrogen is an essential nutrient required for plant growth and development. Even though nitrogen is available in large quantities in the atmosphere, it cannot be utilized by plants directly with the only exception of legumes which have the unique ability to fix atmospheric nitrogen and the process is known as biological nitrogen fixation (BNF). Rhizobium, a group of gram-negative soil bacteria, helps in the formation of root nodules in legumes and takes part in the BNF. The BNF has great significance in agriculture as it acts as a fertility restorer in soil. Continuous cereal-cereal cropping system, which is predominant in a major part of the world, often results in a decline in soil fertility, while legumes add nitrogen and improve the availability of other nutrients too. In the present context of the declining trend of the yield of some important crops and cropping systems, it is the need of the hour for enriching soil health to achieve agricultural sustainability, where Rhizobium can play a magnificent role. Though the role of Rhizobium in biological nitrogen fixation is well documented, their behaviour and performance in different agricultural environments need to be studied further for a better understanding. In the article, an attempt has been made to give an insight into the behaviour, performance and mode of action of different Rhizobium species and strains under versatile conditions.

Weed Management and Crop Establishment Methods in Rice (Oryza sativa L.) Influence the Soil Microbial and Enzymatic Activity in Sub-Tropical Environment.

Weed management has become the most important and inevitable aspect of crop management for achieving a higher rice yield. Nowadays, chemical herbicide application has become a popular practice for managing weeds in different rice cultures. However, herbicide application can have qualitative and quantitative impacts on soil microorganisms and soil enzymes, particularly in the case of new herbicide molecules and their indiscriminate use for a longer period. Further, different rice establishment methods also play a significant role in soil microbial population dynamics as well as soil biological properties. Keeping these in view, a field experiment was conducted at the Agronomy Main Research Farm, Orissa University of Agriculture and Technology (OUAT), India, during the kharif season of 2016 and 2017, on the impact of crop establishment methods and weed management practices on soil microbial and enzymatic status. The field experiment was laid out in a split-plot design with three replications with four crop establishment methods in the main plot, viz., M1, Direct Seeded Rice (DSR); M2, Wet Seeded Rice (WSR); M3,Unpuddled Transplanted Rice (NPTR); M4, Puddled Transplanted Rice (PTR), and six weed management practices in the sub-plot, viz., W1, Weedy check; W2, Bensulfuron methyl 0.6% + Pretilachlor 6% (pre-emergence (PE)) 0.660 kg ha-1 + Hand weeding (HW) at 30 days after sowing/transplanting (days after sowing/transplanting (DAS/T)); W3, Bensulfuron methyl 0.6% + Pretilachlor 6% (PE) 0.495 kg ha-1 + HW at 30 DAS/T; W4, Bensulfuron methyl 0.6% + Pretilachlor 6% (PE) 0.495 kg ha-1 + Bispyribac-Sodium (post-emergence(POE)) 0.025 kg ha-1 at 15 DAS/T; W5, Cono weeding (CW) at 15 DAS/T + hand weeding 30 DAS/T, and W6, Brown manuring/Green manuring. The initial decline in the microbial population was observed due to herbicide application in NPTR and PTR up to 7 DAS/T and then it increased up to 28 DAS/T. There was a reduction in soil microbial and enzymatic status after the application of herbicides Bensulfuron methyl 0.6% + Pretilachlor 6% (PE) and Bispyribac-Sodium (POE) that again followed an upward graph with crop age. Significant variation in enzymatic activity and the microbial count was also observed among treatments involving crop establishment methods. The study revealed that improved microbial population and enzyme activity were noted in unpuddled transplanted rice under organic weed management due to favorable conditions, and chemical weed control initially affected microbial population and activities.

Integrated Nutrient Management Improves the Growth and Yield of Rice and Greengram in a Rice-Greengram Cropping System under the Coastal Plain Agro-Climatic Condition.

Continuous mono-cropping of rice has resulted in decline or stagnation of yield output due to the occurrence of multiple nutrient deficiencies and worsening of soil physicochemical properties accompanying increased pressure of insect pests and diseases. The basic concept of integrated nutrient management (INM) is maintenance or adjustment of soil fertility and supply of plant nutrients to an optimum level for sustaining the desired crop productivity through optimisation of benefits from all possible sources of plant nutrients in an integrated way. Augmenting a rice-based cropping system with pulses is a prevalent and indigenous cropping system under rainfed conditions. Considering the above facts, experiments were conducted to evaluate the impacts of integrated nutrient management on productivity of aromatic rice-greengram cropping system and nutrient balance of the post-harvest soil for agricultural sustainability under rainfed conditions in two consecutive years (2017-2018 and 2018-2019) with six main plots and three subplots. The experimental findings revealed that the treatment comprised of 50% recommended dose of fertiliser (RDF) through chemicals + 50% recommended dose of nitrogen (RDN) through farmyard manure (FYM) increased the plant height, tillers, dry matter accumulation, leaf area and leaf area duration, and yield parameters in short grain aromatic rice. Similarly, preceding application of 50% RDF + 50% RDN through FYM to rice and further application 75% RDF + Rhizobium+ phosphate solubilizing bacteria (PSB) to greengram increased the growth characteristics and yield parameters-such as pods/plant, seeds/pod, grain yield, stover yield, and harvest index-in greengram. It was concluded that the treatment consisting of 50% RDF (chemical fertiliser) + 50% RDN (FYM) to rice and 75% RDF + Rhizobium + PSB to greengram increased the productivity of the rice-greengram cropping system. Furthermore, the adoption of INM has positively impacted post-harvest soil nutrient balance.

The intertwining of Zn-finger motifs and abiotic stress tolerance in plants: Current status and future prospects.

Environmental stresses such as drought, high salinity, and low temperature can adversely modulate the field crop's ability by altering the morphological, physiological, and biochemical processes of the plants. It is estimated that about 50% + of the productivity of several crops is limited due to various types of abiotic stresses either presence alone or in combination (s). However, there are two ways plants can survive against these abiotic stresses; a) through management practices and b) through adaptive mechanisms to tolerate plants. These adaptive mechanisms of tolerant plants are mostly linked to their signalling transduction pathway, triggering the action of plant transcription factors and controlling the expression of various stress-regulated genes. In recent times, several studies found that Zn-finger motifs have a significant function during abiotic stress response in plants. In the first report, a wide range of Zn-binding motifs has been recognized and termed Zn-fingers. Since the zinc finger motifs regulate the function of stress-responsive genes. The Zn-finger was first reported as a repeated Zn-binding motif, comprising conserved cysteine (Cys) and histidine (His) ligands, in Xenopus laevis oocytes as a transcription factor (TF) IIIA (or TFIIIA). In the proteins where Zn2+ is mainly attached to amino acid residues and thus espousing a tetrahedral coordination geometry. The physical nature of Zn-proteins, defining the attraction of Zn-proteins for Zn2+, is crucial for having an in-depth knowledge of how a Zn2+ facilitates their characteristic function and how proteins control its mobility (intra and intercellular) as well as cellular availability. The current review summarized the concept, importance and mechanisms of Zn-finger motifs during abiotic stress response in plants.

Productivity and Nutrient Balance of an Intensive Rice-Rice Cropping System Are Influenced by Different Nutrient Management in the Red and Lateritic Belt of West Bengal, India.

Rice is the lifeline for more than half of the world population, and in India, in view of its huge demand in the country, farmers adopt a rice-rice cropping system where the irrigation facility is available. As rice is a nutrient-exhausting crop, sustainable productivity of rice-rice cropping system greatly depends on appropriate nutrient management in accordance with the inherent soil fertility. The application of an ample dose of fertilizer is the key factor for maintaining sustainable rice yields and nutrient balance of the soil. Considering the above facts, an experiment was conducted on nutrient management in a rice-rice cropping system at the university farm of Visva-Bharati, situated in a sub-tropical climate under the red and lateritic belt of the western part of West Bengal, India, during two consecutive years (2014-2016). The experiment was laid out in a Randomized Completely Block Design with 12 treatments and three replications, with different rates of N:P:K:Zn:S application in both of the growing seasons, namely, kharif and Boro. The recommended (ample) dose of nutrients was 80:40:40:25:20 and 120:60:60:25:20 kg ha-1 of N:P2O5:K2O:Zn:S in the Kharif and Boro season, respectively. A high yielding variety, named MTU 7029, and a hybrid, Arize 6444 GOLD, were taken in the Kharif and Boro seasons, respectively. The results clearly indicated that the application of a recommended dose of nutrients showed its superiority over the control (no fertilizer application) in the expression of growth characters, yield attributes, yields, and nutrient uptake of Kharif as well as Boro rice. Out of the all treatments, the best result was found in the treatment where the ample dose of nutrients was applied, resulting in maximum grain yield in both the Kharif (5.6 t ha-1) and Boro (6.6 t ha-1) season. The corresponding yield attributes for the same treatment in the Kharif (panicles m-2: 247.9; grains panicle-1: 132.0; spikelets panicle-1: 149.6; test weight: 23.8 g; and panicle length: 30.6 cm) and Boro (panicles m-2: 281.6; grains panicle-1: 142.7; spikelets panicle-1: 157.2; test weight: 24.8 g; and panicle length: 32.8 cm) season explained the maximum yield in this treatment. Further, a reduction or omission of individual nutrients adversely impacted on the above traits and resulted in a negative balance of the respective nutrients. The study concluded that the application of a recommended dose of nutrients was essential for proper nutrient balance and sustainable yields in the rice-rice cropping system.

Zinc Biofortification in Food Crops Could Alleviate the Zinc Malnutrition in Human Health.

Micronutrient malnutrition is a global health issue and needs immediate attention. Over two billion people across the globe suffer from micronutrient malnutrition. The widespread zinc (Zn) deficiency in soils, poor zinc intake by humans in their diet, low bioavailability, and health consequences has led the research community to think of an economic as well as sustainable strategy for the alleviation of zinc deficiency. Strategies like fortification and diet supplements, though effective, are not economical and most people in low-income countries cannot afford them, and they are the most vulnerable to Zn deficiency. In this regard, the biofortification of staple food crops with Zn has been considered a useful strategy. An agronomic biofortification approach that uses crop fertilization with Zn-based fertilizers at the appropriate time to ensure grain Zn enrichment has been found to be cost-effective, easy to practice, and efficient. Genetic biofortification, though time-consuming, is also highly effective. Moreover, a Zn-rich genotype once developed can also be used for many years without any recurring cost. Hence, both agronomic and genetic biofortification can be a very useful tool in alleviating Zn deficiency.

Bioinoculants-Natural Biological Resources for Sustainable Plant Production.

Agricultural sustainability is of foremost importance for maintaining high food production. Irresponsible resource use not only negatively affects agroecology, but also reduces the economic profitability of the production system. Among different resources, soil is one of the most vital resources of agriculture. Soil fertility is the key to achieve high crop productivity. Maintaining soil fertility and soil health requires conscious management effort to avoid excessive nutrient loss, sustain organic carbon content, and minimize soil contamination. Though the use of chemical fertilizers have successfully improved crop production, its integration with organic manures and other bioinoculants helps in improving nutrient use efficiency, improves soil health and to some extent ameliorates some of the constraints associated with excessive fertilizer application. In addition to nutrient supplementation, bioinoculants have other beneficial effects such as plant growth-promoting activity, nutrient mobilization and solubilization, soil decontamination and/or detoxification, etc. During the present time, high energy based chemical inputs also caused havoc to agriculture because of the ill effects of global warming and climate change. Under the consequences of climate change, the use of bioinputs may be considered as a suitable mitigation option. Bioinoculants, as a concept, is not something new to agricultural science, however; it is one of the areas where consistent innovations have been made. Understanding the role of bioinoculants, the scope of their use, and analysing their performance in various environments are key to the successful adaptation of this technology in agriculture.