Statistical Methods For Agricultural Workers

Reactive oxygen species (ROS) were initially recognized as toxic by-products of aerobic metabolism. In recent years, it has become apparent that ROS plays an important signaling role in plants, controlling processes such as growth, development and especially response to biotic and abiotic environmental stimuli. The major members of the ROS family include free radicals like O2● −, OH● and non-radicals like H2O2 and 1O2. The ROS production in plants is mainly localized in the chloroplast, mitochondria and peroxisomes. There are secondary sites as well like the endoplasmic reticulum, cell membrane, cell wall and the apoplast. The role of the ROS family is that of a double edged sword; while they act as secondary messengers in various key physiological phenomena, they also induce oxidative damages under several environmental stress conditions like salinity, drought, cold, heavy metals, UV irradiation etc., when the delicate balance between ROS production and elimination, necessary for normal cellular homeostasis, is disturbed. The cellular damages are manifested in the form of degradation of biomolecules like pigments, proteins, lipids, carbohydrates and DNA, which ultimately amalgamate in plant cellular death. To ensure survival, plants have developed efficient antioxidant machinery having two arms, (i) enzymatic components like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR); (ii) non-enzymatic antioxidants like ascorbic acid (AA), reduced glutathione (GSH), α-tocopherol, carotenoids, flavonoids and the osmolyte proline. These two components work hand in hand to scavenge ROS. In this review, we emphasize on the different types of ROS, their cellular production sites, their targets, and their scavenging mechanism mediated by both the branches of the antioxidant systems, highlighting the potential role of antioxidant

Reactive oxygen species (ROS) and response of antioxidants as ROS-scavengers during environmental stress in plants

Global climate change and associated adverse abiotic stress conditions, such as drought, salinity, heavy metals, waterlogging, extreme temperatures, oxygen deprivation, etc., greatly influence plant growth and development, ultimately affecting crop yield and quality, as well as agricultural sustainability in general. Plant cells produce oxygen radicals and their derivatives, so-called reactive oxygen species (ROS), during various processes associated with abiotic stress. Moreover, the generation of ROS is a fundamental process in higher plants and employs to transmit cellular signaling information in response to the changing environmental conditions. One of the most crucial consequences of abiotic stress is the disturbance of the equilibrium between the generation of ROS and antioxidant defense systems triggering the excessive accumulation of ROS and inducing oxidative stress in plants. Notably, the equilibrium between the detoxification and generation of ROS is maintained by both enzymatic and nonenzymatic antioxidant defense systems under harsh environmental stresses. Although this field of research has attracted massive interest, it largely remains unexplored, and our understanding of ROS signaling remains poorly understood. In this review, we have documented the recent advancement illustrating the harmful effects of ROS, antioxidant defense system involved in ROS detoxification under different abiotic stresses, and molecular cross-talk with other important signal molecules such as reactive nitrogen, sulfur, and carbonyl species. In addition, state-of-the-art molecular approaches of ROS-mediated improvement in plant antioxidant defense during the acclimation process against abiotic stresses have also been discussed.

Reactive Oxygen Species and Antioxidant Defense in Plants under Abiotic Stress: Revisiting the Crucial Role of a Universal Defense Regulator

Principles of Plant Breeding

Abiotic stress is a primary threat to fulfill the demand of agricultural production to feed the world in coming decades. Plants reduce growth and development process during stress conditions, which ultimately affect the yield. In stress conditions, plants develop various stress mechanism to face the magnitude of stress challenges, although that is not enough to protect them. Therefore, many strategies have been used to produce abiotic stress tolerance crop plants, among them, ABA (abscisic acid) phytohormone engineering could be one of the methods of choice. ABA is an isoprenoid phytohormone, which regulates various physiological processes ranging from stomatal opening to protein storage and provides adaptation to many stresses like drought, salt, and cold stresses. ABA is also called an important messenger that acts as the signaling mediator for regulating the adaptive response of plants to different environmental stress conditions. In this review, we will discuss the role of ABA in response to abiotic stress at the molecular level and ABA signaling. The review also deals with the effect of ABA in respect to gene expression.

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Abscisic Acid and Abiotic Stress Tolerance in Crop Plants

High temperature (HT) stress is a major environmental stress that limits plant growth, metabolism, and productivity worldwide Plant growth and development involve numerous biochemical reactions that are sensitive to temperature Plant responses to HT vary with the degree and duration of HT and the plant type HT is now a major concern for crop production and approaches for sustaining high yields of crop plants under HT stress are important agricultural goals Plants possess a number of adaptive, avoidance, or acclimation mechanisms to cope with HT situations In addition, major tolerance mechanisms that employ ion transporters, proteins, osmoprotectants, antioxidants, and other factors involved in signaling cascades and transcriptional control are activated to offset stress-induced biochemical and physiological alterations Plant survival under HT stress depends on the ability to perceive the HT stimulus, generate and transmit the signal, and initiate appropriate physiological and biochemical changes HT-induced gene expression and metabolite synthesis also substantially improve tolerance The physiological and biochemical responses to heat stress are active research areas, and the molecular approaches are being adopted for developing HT tolerance in plants This article reviews the recent findings on responses, adaptation, and tolerance to HT at the cellular, organellar, and whole plant levels and describes various approaches being taken to enhance thermotolerance in plants

Physiological, biochemical, and molecular mechanisms of heat stress tolerance in plants

The Deuteromycetes fungal genus Alternaria comprises of different saprophytic as well as endophytic species and is well known for its notoriously destructive plant pathogen members. It has been found to have a drastic effect on the members belonging to the plant families such as Cucurbitaceae, Brassicaceae, Solanaceae which are having nutritional as well as economical food value. Majority of the members of Alternaria lack sexuality altogether, although few species have been found to have sexual stage in their life cycles. Several types of genes ranging from protein encoding genes to those involved in signal transduction cascades are found to be responsible for the pathogenesis. Production of host-specific toxins (HSTs) is found to be an affirming factor of pathogenesis. Most fungal host-specific toxins are metabolites although toxic substances including despipeptides and fucicoccin-like compounds. Genes encoding the biosynthesis of these HSTs are often contained on mostly conditionally dispensable chromosomes. The necrotrophic nature of Alternaria species typically leads to extensive damage of the plant and harvest product, with seedlings seldom surviving an attack. Apart from the role of toxins in Alternaria pathogenesis, few genes and /or gene products have been found to have a propounding effect as a pre-requisite for pathogenicity. For controlling the diseases, numbers of new chemicals are evaluated along with various biological control agents including bacteria, actinomycetes and fungi. Some plants and plant products are also found to be useful in controlling Alternaria infection.

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Alternaria pathogenicity and its strategic controls

Global environmental dissociative changes are now in steady state. Its negative impacts were gradually imposed on a wide range of crops and thus crop improvement was hindered as well. Given this challenge, existing and new, appropriate technologies need to be integrated for global crop improvement. Among the different present approaches, mutagenesis and mutation breeding and the isolation of improved or novel phenotypes in conjunction with conventional breeding programmes can result in mutant varieties endowed with new and desirable variation of agrometrical traits. Induced mutations and its related technologies play very well in this ground and this overall strategy helps to trace the crop genetic diversity along with its biodiversity maintenance. Such induced mutagenesis, a crucial step in crop improvement programme, is now successful in application due to the advancement and incorporation of large-scale selection techniques, micropropagation and other in vitro culture methods, molecular biology tools and techniques in modern crop breeding performance. Time to time, different mutation techniques and their application processes are changing significantly; in this perspective, insertional mutagenesis and retrotransposons are taking more supports for mutational tagging and new mutation generation. For details investigation on plant structure and function, mutagenic agents and their precise role are much essential as it can produce mutants with some phenotypic changes. Functional genomics studies make the ultimatum platform on this field of study where few crop plants were used for mutational experimentation on some prime agronomic traits till now. This is a prerequisite step and is applying on diverse crop for further improvement. High throughput DNA technologies for mutation screening such as TILLING (Targeting Induced Limited Lesions IN Genomes), high-resolution melt analysis (HRM) , ECOTILLING etc. are the key techniques and resources in molecular mutation breeding. Molecular mutation breeding will significantly increase both the efficiency and efficacy of mutation techniques in crop breeding. Such modern and classical technologies are using for the development of mutation induction with the objective of using a set of globally important crops to validate identified relevant novel techniques and build these into modular pipelines to serve as technology packages for induced crop mutations. Thus, mutation assisted plant breeding will play a crucial role in the generation of ‘designer crop varieties’ to address the uncertainties of global climate variability and change, and the challenges of global plant-product insecurity.

Mutagenesis—A Potential Approach for Crop Improvement

In the present study, pure line seeds of mungbean (Vigna radiata L. Wilczek) were treated with four doses (0.2%, 0.4%, 0.6% and 0.8% as w/v) of ethyl methane sulphonate (EMS) to analyse the genetic variability and heritability for some prime agro-metrical traits in second mutant (M2) generation. The analysis of variance revealed highly significant differences among the studied characters. The phenotypic coefficient of variation (PCV) was higher than its genotypic counterpart (GCV) for all the studied traits. The highest GCV (0.537) for number of seeds per pods and highest PCV (0.635) for plant height were recorded in 0.4% EMS treatment. The lowest GCV (0.179) and PCV (0.214) were recorded in the control set for number of pods per plant. The highest broad sense heritability estimate (92.33%) was recorded on 0.4% EMS for plant height. The expected genetic advance was high (42.39%) in 0.4% dose for days to flowering. The lowest heritability (38.43) and genetic advance (5.37) were noticed in control for the total seed yield per plant. EMS at 0.4% and 0.6% concentration gave the maximum values of all the genetic parameters. The increased genetic variability in treated population for these traits has a high scope for selection and can be exploited for the further improvement of mungbean.

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Analysis of Genetic Parameters on Mutant Populations of Mungbean (Vigna radiata L.) after Ethyl Methane Sulphonate Treatment

Sustainable development has caught the imagination and action of the world for more than a decade. Sustainable agriculture is necessary to attain the goal of sustainable development. According to the F ood and Agriculture Organization (FAO), sustainable agr iculture is the successful management of resources to satisfy the changing human needs while maintaining or enhancing the quality of environment and conserving natural resources. All definitions of su stainable agriculture lay great emphasis on maintai ning an agricultural growth rate, which can meet the demand for food of all living beings without draining the basic resources towards crop improvement. Organic farming is one of the several approaches found to meet the objectives of sustainable agriculture. Most of the techniques used in organic farming like intercropping, mulching and integration of crops and liv estock are not alien to agriculture systems including the traditional agricultural practices. H owever, organic farming is based on various laws an d certification programmes, which prohibit the use of almost all synthetic inputs and the central theme of this method is the health of soil. The adverse effe cts of modern agricultural practices on the farm an d also on the health of living beings and thus on the environment has been well documented all over the world. Application of technology, particularly the use of chemical fertilizers and pesticides all arou nd us has persuaded people to think aloud. As a result of global climatic changes, their negative effects on the environment are manifested through soil erosion , water shortages, salination, soil contamination, genetic erosion, Organic farming is one of the wide ly used methods, which is thought as the best alternative to avoid the ill effects of chemical fa rming. It also has far more advantages over the conventional and other modern agricultural practice s that are available today.

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Rajib Roychowdhury

Papers

Physiological, biochemical, and molecular mechanisms of heat stress tolerance in plants

Alternaria pathogenicity and its strategic controls

Mutagenesis—A Potential Approach for Crop Improvement

Analysis of Genetic Parameters on Mutant Populations of Mungbean (Vigna radiata L.) after Ethyl Methane Sulphonate Treatment

Organic farming for crop improvement and sustainable agriculture in the era of climate change