Mung bean, a legume, is sensitive to abiotic stresses at different growth stages, and its yield potential is affected by drought and high-temperature stress at the sensitive stage. Melatonin is a multifunctional hormone that plays a vital role in plant stress defense mechanisms. This study aimed to evaluate the efficiency of melatonin under individual and combined drought and high-temperature stress in mung bean. An experiment was laid out with five treatments, including an exogenous application of 100 µM melatonin as a seed treatment, foliar spray, and a combination of both seed treatment and foliar spray, as well as absolute control (ambient condition) and control (stress without melatonin treatment). Stresses were imposed during the mung bean’s reproductive stage (31–40 DAS) for ten days. Results revealed that drought and high-temperature stress significantly decreased chlorophyll index, Fv/Fm ratio, photosynthetic rate, stomatal conductance, and transpiration rate through increased reactive oxygen species (ROS) production. Foliar application of melatonin at 100 µM concentration enhanced the activity of antioxidant enzymes such as superoxide dismutase, catalase, and ascorbate peroxidase and the concentration of metabolites involved in osmoregulation and ion homeostasis; thereby, it improves physiological and yield-related traits in mung bean under individual and combined stress at the reproductive stage.

In tomato (Lycopersicon esculentum L.), the effects of combined drought (D) and high temperature (HT) stress during the flowering stage had not been studied in detail. Therefore, this study was conducted with an objective of quantifying the effects of foliar spray of melatonin under individual and combined drought and HT stress. At flowering stage, D stress was imposed through withholding irrigation, while HT stress was imposed through exposing the plants to ambient temperature (AT) along with an increase of +5 °C. Under D + HT, plants were first subjected to drought followed by a + 5 °C increase in AT. The duration of individual or combined stress was ten days. At 80% available soil moisture, 100 µM melatonin was sprayed on D, HT, or D + HT treated plants. Among the stresses, D + HT stress increased the thylakoid membrane damage and decreased the photosynthetic rate and fruit yield more than D or HT stress. Foliar spray of 100 µM melatonin produced decreased thylakoid membrane damage [D: 31%, HT: 26%, and D + HT: 18%] and increased antioxidant enzyme, viz., superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, and glutathione reductase, activity over stress-control plants. The photosynthetic rate [D: 24%, HT: 22%, and D + HT: 19%] and fruit yield [D: 32%, HT: 23%, and D + HT: 16%] were increased over stress-control plants. Hence, it is evident that the increased photosynthetic rate and fruit yield in D + HT and 100 µM melatonin-sprayed plants may be associated with an increased antioxidant defense system. Melatonin as a novel biostimulator has a great potential in scavenging free radicals through increased antioxidant activity, which shields the photosynthetic membrane from damage and therefore helps in stress mitigation.

Aim: Micro encapsulation of diclosulam herbicide was done in xanthan gum based polymeric system through ionotropic gelation method to formulate a slow-release herbicide to achieve prolonged weed control in irrigated upland ecosystem. Place and Duration of Study: The slow-release formulation of diclosulam was synthesized and characterized in the Department of Nano Science & Technology, Tamil Nadu Agricultural University during January to July 2022. Methodology: Xanthan gum- alginate microsphere system was synthesized with varying concentrations of calcium chloride (CaCl₂) (2, 4 and 6 per cent) to encapsulate diclosulam through ionotropic gelation. The size, entrapment efficiency, pore volume, pore radius, surface area and swelling behavior of microspheres were assessed to achieve higher loading of diclosulam and good stability of microspheres. Results: The mean diameter of xanthan gum-alginate microsphere was higher with 6 per cent ion gelation bath followed by the concentration of 4 and 2 per cent. Higher entrapment efficiency of diclosulam was achieved with loading of two percent diclosulam in six per cent calcium crosslinked microspheres. Conclusion: Xanthan gum-alginate microsphere system offers both burst release and controlled release of active ingredients. However, controlled release polymeric templates with herbicide will synchronize the release of herbicide with the emergence of weeds in the cropped situations for better weed management.

Aim: The study was conducted to design pectin beads for achieving slow release of agrochemicals in wetlands via ion gelation method. Place and Duration of the Study: The laboratory experiment was carried out at the Department of Nano Science & Technology, Tamil Nadu Agricultural University, Tamil Nadu during March-July 2021. Methodology: Pectin beads were synthesized varying the concentrations of pectin (4, 6, 8, and 10 per cent) and calcium chloride (CaCl₂) concentrations (0.5, 1, and 2 per cent). Calcium pectinate beads of different combinations were synthesized via ion gelation method. Calcium pectinate beads were characterized based on the recovery yield of beads, while surface characterization was done through Scanning electron microscope (SEM) and optical microscope to understand the topography of beads and assess the size of the beads respectively. Pore volume and surface area were also studied using BET (Brunauer-Emmett-Teller) analyzer. Results: The yield of calcium pectinate beads were higher while using the concentration of pectin @ 4 per cent and CaCl₂ @ 2 per cent as cross-linking agent. The spherical and smooth surface of beads was achieved with the concentrations of 6 and 2 per cent pectin and CaCl₂ respectively, while beads were flat and smooth with concentration of pectin @ 4 per cent. Similarly, complete solubility of pectin was not achieved with concentrations of 8 and 10 per cent. BET results of beads showed that beads are non-porous in nature. Conclusion: Pectin and CaCl₂ concentrations @ 6 and 2 per cent respectively were found to be ideal for the delivery of agrochemical based on the yield and surface morphology.

Nanotechnology holds significant potential in agriculture, contributing to various applications such as nanofertilizers, nanopesticides, nanoherbicides, nanosensors and more recently, electrospun nanofibers. Among such advancements, electrospinning has emerged as a versatile and cost-effective technique for fabricating nanofibers, offering significant potential to enhance sustainability in agricultural practices. Recent applications of electrospun fibers have primarily focused on drug delivery, wound dressings and seed coatings infused with growth hormones. These nanofibers exhibit notable properties such as a high surface-area-to-volume ratio, excellent porosity and the ability to facilitate controlled release of active compounds. Encapsulating microorganisms and agrochemicals within electrospun fibers offers an environmentally friendly approach to improve soil health. By forming a protective layer, the electrospun nanofibers help safeguard seeds against abiotic factors such as drought and temperature fluctuations, as well as biotic threats like pathogens and pests. Furthermore, embedding natural or synthetic antimicrobial agents into electrospun films offers an eco-friendly solution for post-harvest protection by effectively minimizing spoilage and the risk of pathogen invasion. This review emphasizes the diverse roles of electrospun nanofibers in sustainable agriculture, including soil enhancement, seed improvement and post-harvest protection, while also promoting eco-friendly practices using biodegradable polymers and bioactive agents.