Enhancement of Drought Tolerance in Cucumber Plants by Natural Carbon Materials

Carbon nanotubes in plant dynamics: Unravelling multifaceted roles and phytotoxic implications

Carbon nanotubes (CNTs) have emerged as a promising frontier in plant science owing to their unique physicochemical properties and versatile applications. CNTs enhance stress tolerance by improving water dynamics and nutrient uptake and activating defence mechanisms against abiotic and biotic stresses. They can be taken up by roots and translocated within the plant, impacting water retention, nutrient assimilation, and photosynthesis. CNTs have shown promise in modulating plant-microbe interactions, influencing symbiotic relationships and mitigating the detrimental effects of phytopathogens. CNTs have demonstrated the ability to modulate gene expression in plants, offering a powerful tool for targeted genetic modifications. The integration of CNTs as sensing elements in plants has opened new avenues for real-time monitoring of environmental conditions and early detection of stress-induced changes. In the realm of agrochemicals, CNTs have been explored for their potential as carriers for targeted delivery of nutrients, pesticides, and other bioactive compounds. CNTs have the potential to demonstrate phytotoxic effects, detrimentally influencing both the growth and developmental processes of plants. Phytotoxicity is characterized by induction of oxidative stress, impairment of cellular integrity, disruption of photosynthetic processes, perturbation of nutrient homeostasis, and alterations in gene expression. This review aims to provide a comprehensive overview of the current state of knowledge regarding the multifaceted roles of CNTs in plant physiology, emphasizing their potential applications and addressing the existing challenges in translating this knowledge into sustainable agricultural practices.

Attenuation of Zucchini mosaic virus disease in cucumber plants by mycorrhizal symbiosis

KEY MESSAGE

Arbuscular mycorrhizal fungi generated systemic acquired resistance in cucumber to Zucchini yellow mosaic virus, indicating their prospective application in the soil as a sustainable, environmentally friendly approach to inhibit the spread of pathogens. The wide spread of plant pathogens affects the whole world, causing several plant diseases and threatening national food security as it disrupts the quantity and quality of economically important crops. Recently, environmentally acceptable mitigating practices have been required for sustainable agriculture, restricting the use of chemical fertilizers in agricultural areas. Herein, the biological control of Zucchini yellow mosaic virus (ZYMV) in cucumber (Cucumis sativus L.) plants using arbuscular mycorrhizal (AM) fungi was investigated. Compared to control plants, ZYMV-infected plants displayed high disease incidence (DI) and severity (DS) with various symptoms, including severe yellow mosaic, mottling and green blisters of leaves. However, AM fungal inoculation exhibited 50% inhibition for these symptoms and limited DS to 26% as compared to non-colonized ones. The detection of ZYMV by the Enzyme-Linked Immunosorbent Assay technique exhibited a significant reduction in AM-inoculated plants (5.23-fold) compared with non-colonized ones. Besides, mycorrhizal root colonization (F%) was slightly reduced by ZYMV infection. ZYMV infection decreased all growth parameters and pigment fractions and increased the malondialdehyde (MDA) content, however, these parameters were significantly enhanced and the MDA content was decreased by AM fungal colonization. Also, the protein, proline and antioxidant enzymes (POX and CAT) were increased with ZYMV infection with more enhancements due to AM root colonization. Remarkably, defence pathogenesis-related (PR) genes such as PR-a, PR-b, and PR-10 were quickly expressed in response to AM treatment. Our findings demonstrated the beneficial function of AM fungi in triggering the plant defence against ZYMV as they caused systemic acquired resistance in cucumber plants and supported their potential use in the soil as an environment-friendly method of hindering the spread of pathogenic microorganisms sustainably.

Multiple Stressors in Vegetable Production: Insights for Trait-Based Crop Improvement in Cucurbits

Vegetable production is a key determinant of contribution from the agricultural sector toward national Gross Domestic Product in a country like India, the second largest producer of fresh vegetables in the world. This calls for a careful scrutiny of the threats to vegetable farming in the event of climate extremes, environmental degradation and incidence of plant pests/diseases. Cucurbits are a vast group of vegetables grown almost throughout the world, which contribute to the daily diet on a global scale. Increasing food supply to cater to the ever-increasing world population, calls for intensive, off-season and year-round cultivation of cucurbits. Current situation predisposes these crops to a multitude of stressors, often simultaneously, under field conditions. This scenario warrants a systematic understanding of the different stress specific traits/mechanisms/pathways and their crosstalk that have been examined in cucurbits and identification of gaps and formulation of perspectives on prospective research directions. The careful dissection of plant responses under specific production environments will help in trait identification for genotype selection, germplasm screens to identify superior donors or for direct genetic manipulation by modern tools for crop improvement. Cucurbits exhibit a wide range of acclimatory responses to both biotic and abiotic stresses, among which a few like morphological characters like waxiness of cuticle; primary and secondary metabolic adjustments; membrane thermostability, osmoregulation and, protein and reactive oxygen species homeostasis and turnover contributing to cellular tolerance, appear to be common and involved in cross talk under combinatorial stress exposures. This is assumed to have profound influence in triggering system level acclimation responses that safeguard growth and metabolism. The possible strategies attempted such as grafting initiatives, molecular breeding, novel genetic manipulation avenues like gene editing and ameliorative stress mitigation approaches, have paved way to unravel the prospects for combined stress tolerance. The advent of next generation sequencing technologies and big data management of the omics output generated have added to the mettle of such emanated concepts and ideas. In this review, we attempt to compile the progress made in deciphering the biotic and abiotic stress responses of cucurbits and their associated traits, both individually and in combination.

Productivity Enhancement of Cucumber (Cucumis sativus L.) through Optimized Use of Poultry Manure and Mineral Fertilizers under Greenhouse Cultivation

Cucumber, a widely cultivated vegetable, is mostly grown under greenhouse conditions. In recent years, the overuse of inorganic fertilizers for higher yield attainment adversely has affected human health and the environment. Therefore, a greenhouse experiment was designed to evaluate the effects of different nutrient sources (poultry manure (PM) and mineral fertilizer (MF)) on productivity-enhancing parameters of cucumber via univariate and multivariate analyses. Amounts of PM and MF (NPK15:15:15) were added to coco-peat per cubic meter by weight/volume (w/v) ratios as follows: T1 (control), 60 kg PM; T2, 30 kg PM + 3 kg MF; T3, 30 kg PM + 5 kg MF, and T4, 30 kg PM + 7 kg MF. The univariate analysis performed on the collected data illustrated the significant enhancement in growth and productivity for the integrated use of PM and MF. Multivariate analyses (correlation, clustering, and Principal Component Analysis) validated the results of univariate analysis by differentiating treatments into two groups. The three treatments obtained a distinguished group from T1 (Control) and did not show significant differences among each other, with a maximum yield increase by T2 (74.6%). According to these results, T2 could improve cucumber productivity under greenhouse conditions. It can be taken as recommendations for better quality and yield enhancement in future improvement programs and cucumber-related farming communities.

Crop Enhancement of Cucumber Plants under Heat Stress by Shungite Carbon

Heat stress negatively impacts plant growth and yield. The effects of carbon materials on plants in response to abiotic stress and antioxidant activity are poorly understood. In this study, we propose a new method for improving heat tolerance in cucumber (Cucumis sativus L.) using a natural carbon material, shungite, which can be easily mixed into any soil. We analyzed the phenotype and physiological changes in cucumber plants maintained at 35 °C or 40 °C for 1 week. Our results show that shungite-treated cucumber plants had a healthier phenotype, exhibiting dark green leaves, compared to the plants in the control soil group. Furthermore, in the shungite-treated plants, the monodehydroascorbate content (a marker of oxidative damage) of the leaf was 34% lower than that in the control group. In addition, scavengers against reactive oxygen species, such as superoxide dismutase, catalase, and peroxidase were significantly upregulated. These results indicate that the successive pre-treatment of soil with a low-cost natural carbon material can improve the tolerance of cucumber plants to heat stress, as well as improve the corresponding antioxidant activity.