Abiotic Stress in Rice: Visiting the Physiological Response and Its Tolerance Mechanisms

Rice (Oryza sativa L.) is one of the most significant staple foods worldwide. Carbohydrates, proteins, vitamins, and minerals are just a few of the many nutrients found in domesticated rice. Ensuring high and constant rice production is vital to facilitating human food supplies, as over three billion people around the globe rely on rice as their primary source of dietary intake. However, the world’s rice production and grain quality have drastically declined in recent years due to the challenges posed by global climate change and abiotic stress-related aspects, especially drought, heat, cold, salt, submergence, and heavy metal toxicity. Rice’s reduced photosynthetic efficiency results from insufficient stomatal conductance and natural damage to thylakoids and chloroplasts brought on by abiotic stressor-induced chlorosis and leaf wilting. Abiotic stress in rice farming can also cause complications with redox homeostasis, membrane peroxidation, lower seed germination, a drop in fresh and dry weight, necrosis, and tissue damage. Frequent stomatal movements, leaf rolling, generation of reactive oxygen radicals (RORs), antioxidant enzymes, induction of stress-responsive enzymes and protein-repair mechanisms, production of osmolytes, development of ion transporters, detoxifications, etc., are recorded as potent morphological, biochemical and physiological responses of rice plants under adverse abiotic stress. To develop cultivars that can withstand multiple abiotic challenges, it is necessary to understand the molecular and physiological mechanisms that contribute to the deterioration of rice quality under multiple abiotic stresses. The present review highlights the strategic defense mechanisms rice plants adopt to combat abiotic stressors that substantially affect the fundamental morphological, biochemical, and physiological mechanisms

Frankia‑actinorhizal symbiosis: A non‑chemical biological assemblage for enhanced plant growth, nodulation and reclamation of degraded soils

Actinorhizal symbiosis naturally harbours beneficial categories of diverse plant growth promoting microorganisms (PGPMs), including the Frankia species. The beneficial microorganisms can be used as efficient, non-chemical and sustainable alternatives for adopting effective soil restoration programmes and revegetation schedules in chemical and industrial-contaminated sites, including treating degraded lands contaminated with toxic chemicals and pesticides. It has been proposed that the interactions between the microbial gene pool are of immense agricultural significance that would facilitate an improvement in the health, hygiene and nutrient acquisition pathway of native soil. The present review is focused on exploiting the hitherto-unexplored Frankia-actinorhizal symbiosis with due interest for their application in soil restoration programmes, including the reclamation of degraded lands. This opens up new insights for the development of sustainability in forestry and plantation research. Additionally, it would promise an improvement in plant growth and vigour, hygiene, and other parameters related to crop yield, such as plant biomass, root/shoot ratio, crop yield, and so on. Novel and putative microorganisms isolated from the actinorhizal may be used for bio-transformation of allelochemicals and toxic heavy metals into compounds with modified biological properties, opening up novel avenues for mediating microbial degradation of putative allelochemicals that would otherwise accumulate at phytotoxic levels in soil. Endophyte-host specificities, the phylogeny of Frankia, and the conservation of unique endemic plant genetic resources like actinorhizal plants, are of paramount significance in the advancement of genomics, metabolomics and phenomics

Residue and soil dissipation kinetics of chloroacetanilide herbicides on rice (Oryzae sativa L.) and assessing the impact on soil microbial parameters and enzyme activity

The present investigation determines the persistence of herbicides like butachlor and pretilachlor in Indian soil, and their impact on soil biological properties including microbial biomass carbon (MBC), total microbial population numbers, and enzyme activities. Butachlor was degraded faster in autumn rice soil (t1/2 of 10–13 days) than in winter rice soil (half-life of 16–18 days). The t1/2 of pretilachlor in winter rice was 12–16 days. Regardless of the seasons under cultivation, no pesticide residue was detected in rice at harvest. Herbicides induced an initial decline (0–14th days after application) in MBC (averages of 332.7–478.4 g g−1 dry soil in autumn rice and 299.6–444.3 g g−1 dry soil in winter rice), microbial populations (averages of 6.4 cfu g−1 in autumn rice and 4.6 cfu g−1 in winter rice), and phosphatase (averages of 242.6–269.3 μg p-nitrophenol g−1 dry soil h−1 in autumn rice and 188.2–212.2 μg p-nitrophenol g−1 dry soil h−1 in winter rice). The application of herbicides favored dehydrogenase (averages of 123.1–156.7 g TPF g−1 dry soil in autumn and 126.7–151.1 g TPF g−1 dry soil in winter) and urease activities (averages of 279.0–340.4 g NH4 g−1 soil 2 h−1 in autumn and 226.7–296.5 g NH4 g−1 soil 2 h−1 in winter) in rice soil at 0–14th DAA. The study suggests that applications of butachlor and pretilachlor at the rates of 1000 g ha−1 and 750 g ha−1, respectively, to control the weeds in the transplanted rice fields do not have any negative impact on the harvested rice and associated soil environment

Biochar as Soil Amendment in Climate-Smart Agriculture: Opportunities, Future Prospects, and Challenges

International audienceThere appears to be an increasing demand for quality food and fodder to ensure environmental safety. Although chemical fertilizers and pesticides are widely used to increase crop yield and plant protection, the unauthorized and injudicious use of chemicals negatively affects native flora and fauna and depletes natural soil fertility, culminating in quality loss, climate crisis, and global warming. Recently, there has been a lot of focus on using biochar to improve soil health, mitigate soil degradation, and control soil and water pollution because biochar restores ecosystems and enhances soil quality. Biochar is a solid, carbon-rich material with a high surface area and improved nutrient content that exhibits slow nutrient release properties obtained through the pyrolysis of various biochar-based environmental materials. Sustainable biochar release in the soil can improve plant growth through nutrient use efficiencies, enhancing beneficial plant-microbe interactions, and plant protection. The current review summarizes the properties and cost-effective production technologies of quality biochar, sustainable application, action mechanisms for improving soil properties, and prominent plant-microbe interactions for enhanced plant growth and survival under climate-smart agriculture. Biochar's agronomic potential in the soil is affected by physical and chemical properties, such as surface area, particle density, and pore size distribution, as well as pH, electrical conductivity, total and plant-available concentrations of carbon, nitrogen, potassium, and phosphorus, cation exchange capacity, and certain minor nutrients. Additionally, the essential requirements of healthy soil and associated attributes of good agricultural practices are addressed, along with the key benefits, limitations, and opportunities of biochar application for enhancing sustainability in agriculture