Mohsin Tanveer

Drought induced changes in growth, osmolyte accumulation and antioxidant metabolism of three maize hybrids

Consequences of drought stress in crop production systems are perhaps more deleterious than other abiotic stresses under changing climatic scenarios. Regulations of physio-biochemical responses of plants under drought stress can be used as markers for drought stress tolerance in selection and breeding. The present study was conducted to appraise the performance of three different maize hybrids (Dong Dan 80, Wan Dan 13, and Run Nong 35) under well-watered, low, moderate and SD conditions maintained at 100, 80, 60, and 40% of field capacity, respectively. Compared with well-watered conditions, drought stress caused oxidative stress by excessive production of reactive oxygen species (ROS) which led to reduced growth and yield formation in all maize hybrids; nevertheless, negative effects of drought stress were more prominent in Run Nong 35. Drought-induced osmolyte accumulation and strong enzymatic and non-enzymatic defense systems prevented the severe damage in Dong Dan 80. Overall performance of all maize hybrids under drought stress was recorded as: Dong Dan 80 > Wan Dan 13 > Run Nong 35 with 6.39, 7.35, and 16.55% yield reductions. Consequently, these biochemical traits and differential physiological responses might be helpful to develop drought tolerance genotypes that can withstand water-deficit conditions with minimum yield losses.

Responses of rapid viscoanalyzer profile and other rice grain qualities to exogenously applied plant growth regulators under high day and high night temperatures

High-temperature stress degrades the grain quality of rice; nevertheless, the exogenous application of plant growth regulators (PGRs) might alleviate the negative effects of high temperatures. In the present study, we investigated the responses of rice grain quality to exogenously applied PGRs under high day temperatures (HDT) and high night temperatures (HNT) under controlled conditions. Four different combinations of ascorbic acid (Vc), alpha-tocopherol (Ve), brassinosteroids (Br), methyl jasmonates (MeJA) and triazoles (Tr) were exogenously applied to two rice cultivars (IR-64 and Huanghuazhan) prior to the high-temperature treatment. A Nothing applied Control (NAC) was included for comparison. The results demonstrated that high-temperature stress was detrimental for grain appearance and milling qualities and that both HDT and HNT reduced the grain length, grain width, grain area, head rice percentage and milled rice percentage but increased the chalkiness percentage and percent area of endosperm chalkiness in both cultivars compared with ambient temperature (AT). Significantly higher grain breakdown, set back, consistence viscosity and gelatinization temperature, and significantly lower peak, trough and final viscosities were observed under high-temperature stress compared with AT. Thus, HNT was more devastating for grain quality than HDT. The exogenous application of PGRs ameliorated the adverse effects of high temperature in both rice cultivars, and Vc+Ve+MejA+Br was the best combination for both cultivars under high temperature stress.

Lithium toxicity in plants: Reasons, mechanisms and remediation possibilities – A review

Lithium (Li) is a naturally occurring element; however, it is one of the non-essential metals for life. Lithium is becoming a serious matter of discussion for the people who do research on trace metals and environmental toxicity in plants. Due to limited information available regarding its mobility from soil to plants, the adverse effects of Li toxicity to plants are still unclear. This article briefly discusses issues around Li, its role and its essentiality in plants and research directions that may assist in inter-disciplinary studies to evaluate the importance of Lis toxicity. Further, potential remediation approaches will also be highlighted in this review. Briefly, Li influenced the growth of plants in both stimulation and reduction ways, depending on the concentration of Li in growth medium. On the negative side, Li reduces the plant growth by interrupting numerous physiological processes and altering metabolism in plant. The contamination of soil by Li is becoming a serious problem, which might be a threat for crop production in the near future. Additionally, lack of considerable information about the tolerance mechanisms of plants further intensifies the situation. Therefore, future research should emphasize in finding prominent and approachable solutions to minimize the entry of Li from its sources (especially from Li batteries) into the soil and food chain.

Is lithium biologically an important or toxic element to living organisms? An overview

Industrialized world is exposing living organisms to different chemicals and metals such as lithium (Li). Due to their use in common household items to industrial applications, it is imperative to examine their bioavailability. Lithium belongs to the group IA and also has wider uses such as in batteries, air conditioners to atomic reactors. Lithium occurs naturally in soil and water, mostly at low concentrations, and enters the food chain. It is not one of the essential minerals though various studies indicate that low levels of Li have beneficial effects on living organisms, whereas high levels expose them to toxicity and related detrimental effects. This review suggests that Li could be biologically important to living organism depending upon its concentration/exposure. Little is known about its biological importance and molecular understanding of its accumulation and mode of action, which might have future implications for Li’s long-term effects on living organisms.

Relay cropping as a sustainable approach: problems and opportunities for sustainable crop production.

Climate change, soil degradation, and depletion of natural resources are becoming the most prominent challenges for crop productivity and environmental sustainability in modern agriculture. In the scenario of conventional farming system, limited chances are available to cope with these issues. Relay cropping is a method of multiple cropping where one crop is seeded into standing second crop well before harvesting of second crop. Relay cropping may solve a number of conflicts such as inefficient use of available resources, controversies in sowing time, fertilizer application, and soil degradation. Relay cropping is a complex suite of different resource-efficient technologies, which possesses the capability to improve soil quality, to increase net return, to increase land equivalent ratio, and to control the weeds and pest infestation. The current review emphasized relay cropping as a tool for crop diversification and environmental sustainability with special focus on soil. Briefly, benefits, constraints, and opportunities of relay cropping keeping the goals of higher crop productivity and sustainability have also been discussed in this review. The research and knowledge gap in relay cropping was also highlighted in order to guide the further studies in future.

Role of 24-epibrassinolide (EBL) in mediating heavy metal and pesticide induced oxidative stress in plants: A review

Industrialization and urbanization have posed serious threats to the environment. Excessive release of heavy metals from industrial effluents and overuse of pesticides in modern agriculture are limiting crop production by polluting environment and deteriorating food quality. Sustaining food quality under heavy metals and pesticide stress is crucial to meet the increasing demands for food. 24-Epibrassinolide (EBL), a ubiquitously occurring plant growth hormone shows great potential to alleviate heavy metals and pesticide stress in plants. This review sums up the potential role of EBL in ameliorating heavy metals and pesticide toxicity in plants extensively. EBL application increases plants overall growth, biomass accumulation and photosynthetic efficiency by the modulation of numerous biochemical and physiological processes under heavy metals and pesticide stress. In addition, EBL scavenges reactive oxygen species (ROS) by triggering the production of antioxidant enzymes such as SOD, CAT, POX etc. EBL also induces the production of proline and soluble proteins that helps in maintaining osmotic potential and osmo-protection under both heavy metals and pesticide stress. At the end, future needs of research about the application of 24-epibrassinolide have also been discussed.

Phyto-toxicity of chromium in maize: oxidative damage, osmolyte accumulation, anti-oxidative defense and chromium uptake

Agricultural production systems are immensely exposed to different environmental stresses in which heavy metal stress receives serious concerns. This study was conducted to explore the deleterious effects of different chromium (Cr) stress levels, i.e., 0, 30, 60, 90, 120, and 150 μmol L−1, on two maize genotypes, Wandan 13 and Runnong 35. Both genotypes were evaluated by measuring their growth and yield characteristics, Cr accumulation in different plant tissues, alterations in osmolyte accumulation, generation of reactive oxygen species (ROS), and anti-oxidative enzyme activity to scavenge ROS. The results showed that Cr stress decreased the leaf area, cob formation, 100-grain weight, shoot fresh biomass, and yield formation, while Cr accumulation in different maize tissues was found in the order of roots > leaves > stem > seeds in both genotypes. The increased Cr toxicity resulted in higher free proline, soluble sugars and total phenolic contents, and lower soluble protein contents. However, enhanced lipid peroxidation was noticed in the forms of malondialdehyde, hydrogen peroxide (H2O2) and thiobarbituric acid reactive substance accumulation, and electrolyte leakage. The hyperactivity of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, especially glutathione peroxidase and glutathione reductase indicated that these anti-oxidative enzymes had a central role in protecting maize from Cr toxicity, especially for Wandan 13. Moreover, higher uptake and less translocation of Cr contents into the grains of Wandan 13 implied its importance as a potential candidate against soil Cr pollution.

An insight into salt stress tolerance mechanisms of Chenopodium album

Salt stress is one of the most dramatic abiotic stresses that induce oxidative and osmotic stress simultaneously. Salt stress is known to be more effective in reducing growth and yield of glycophytes; however, halophytes are able to withstand salt stress. Nonetheless, variability exists among different halophytic plants species from different plant families. Chenopodium album belongs to Chenopodiacea family and is known as weed in many regions of world; however, it is a very interesting halophytic plant. Little research has conducted so far by considering C. album as model plant to study salt stress tolerance mechanisms. This article attempts to compile current literature in order to explain C. album salt stress tolerance mechanism and to highlight the knowledge gap relating to salt stress tolerance mechanism in C. album. Briefly, C. album has remarkable ability of seed dimorphism, sodium exclusion, and potassium retention. C. album further tolerates salt stress by increasing redox potential associated with high production of osmolytes and antioxidants.

Beryllium in the environment: Whether fatal for plant growth?

Beryllium could be a threatening heavy metal pollutant in the agro-ecosystem that may severely affect the performance of crops. Beryllium is used in various industries to make nuclear weapons and reactors, aircraft and space vehicle structures, instruments, and X-ray machines, and its entry into the environment is alarming for the productivity and sustainability of the ecosystem. In this review, we present a contemporary synthesis of the existing data regarding the toxic effects of beryllium on toxicity on biochemical and physiological processes in plants. Moreover, uptake, translocation, and assimilation of beryllium and its interaction with some essential mineral elements are also discussed. Although limited data are available regarding biochemical responses of plants to beryllium toxicity, we tried to clarify some basic physiological and biochemical steps that can be hampered by beryllium in plants. We linked our hypothetical concepts with previous evidence and provide a comprehensive summary of all possible remediation strategies that can be used for plants. Overall, we hope this review will be beneficial due to its practical implications and research directions.

Targeting Redox Regulatory Mechanisms for Salinity Stress Tolerance in Crops

Salinity stress is one of the major abiotic stresses that result in significant losses in agricultural crop production across the globe. Salinity stress results in osmotic stress, ionic stress, and oxidative stress; among these, oxidative stress is considered to be the most detrimental. Oxidative stress induces the production of different reactive oxygen species (ROS) at both intracellular and extracellular locations. Plants possess redox regulatory mechanisms by employing different enzymatic and nonenzymatic antioxidants to scavenge ROS. Different antioxidants have different tissue- and organelle-specific ROS-scavenging effects. However, the causal link between the amount of antioxidants and plant salinity stress tolerance is not as straightforward as one may assume, with controversial reports available in the literature. This chapter addresses those controversies and argues that there is a need for better understanding and development of tools for targeted regulation of plant redox systems in specific cellular compartments and tissues.