Aradhna Kumari

Constructed wetlands (CWs) are sustainable and cost-effective systems that utilise plant–microbe interactions and natural processes for wastewater treatment. Microbial communities play a pivotal role in pollutant removal by crucial processes like nitrogen transformations, phosphorus cycling, organic matter degradation and the breakdown of emerging contaminants. Dominant phyla, such as Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes, collectively orchestrate these biogeochemical functions. Advances in molecular tools, including high-throughput sequencing and metagenomics, have revealed the diversity and functional potential of wetland microbiomes, while environmental factors, i.e., temperature, pH and hydraulic retention time, strongly influence their performance. Phosphorus removal efficiency is often lower than nitrogen, and large land requirements and long start-up times restrict broader application. Microplastic accumulation, the spread of antibiotic resistance genes and greenhouse gas emissions (methane, nitrous oxide) present additional challenges. The possible persistence of pathogenic microbes further complicates system safety. Future research should integrate engineered substrates, biochar amendments, optimised plant–microbe interactions and hybrid CW designs to enhance treatment performance and resilience in the era of climate change. By acknowledging the potential and constraints, CWs can be further developed as next-generation, nature-based solutions for sustainable water management in the years to come.

Background: The rapid increase in population, urbanization and climate change have severely impacted global food production. Currently, global agriculture is facing a major threat due to erratic weather conditions, a decline in natural resources and deteriorating soil fertility. The efficient management and utilization of natural resources along with the applied fertilizers is essential at this point. Methods: Considering the nature of situation, the field experiment was conducted in the spring season of 2022 and 2023 to evaluate the influence of crop geometry and various sources of fertilizers on the morphology and yield of spring maize. The field trial was carried out in the split-plot design with three types of crop geometry i.e., 40 x 40 cm; 50 x 50 cm and 60 x 20 cm; and four different sources of fertilizers i.e., nano fertilizers, ferti-capsule, customized fertilizers and normal fertilizers. Result: The results revealed that the growth parameters like plant height (cm) and number of leaves were significantly affected under the treatment 6 (50 x 50 cm + nano fertilizers), while the grain yield and stover yield (kg/ha), were impacted by the treatment 10 i.e., 60 x 20 cm + nano fertilizers. The employment of treatment 6 aided in enhancing the productivity per plant, while the former assisted in achieving the highest production per hectare.

Background: Poor translocation of micronutrients especially zinc (Zn) within plants poses a significant constraint on the growth of cereal crops. The present study investigated the effect of various Zn application methods and plant growth regulators (gibberellic acid (GA) and cytokinin) on the growth of rice crop. Methods: The experiment was carried out using a split-split plot design with three replications to assess two rice varieties (SAVA 127 and PR 126) under three Zn application methods: no Zn application (Zn0), soil Zn application (Zn1) and soil + foliar Zn application (Zn2) along with four PGR levels: no PGR application (H0), 10 mg L-1 GA (H1), 10 mg L-1 cytokinin (H2) and 5 mg L-1 GA + 5 mg L-1 cytokinin (H3). Result: Plant height was increased by 14.4% in variety SAVA 127 with foliar spray of 10 mg L-1 GA along with soil + foliar Zn application method. Application of 10 mg L-1 cytokinin in combination with soil + foliar Zn application method significantly enhanced growth parameters, where number of leaves per plant, leaf area index (LAI) and dry matter accumulation (DMA) were increased by 18.7, 36.0 and 41.6% respectively as compared to control in the variety SAVA 127. On the other hand, the maximum number of tillers per square meter (6.7% higher than control) was noted in variety PR 126. Overall, combined approach of soil + foliar Zn application along with 10 mg L-1 cytokinin was found as a superior option in improving various growth parameters of rice varieties.

Soil microbes are microscopic organisms that inhabit the soil and play a significant role in various ecological processes. They are essential for nutrient cycling, carbon sequestration, and maintaining soil health. Importantly, soil microbes have the potential to sequester carbon dioxide (CO₂) from the atmosphere through processes like carbon fixation and storage in organic matter. Unlocking the potential of microbial-driven carbon storage holds the key to revolutionizing climate-smart agricultural practices, paving the way for sustainable productivity and environmental conservation. A fascinating tale of nature’s unsung heroes is revealed by delving into the realm of soil microbes. The guardians of the Earth are these tiny creatures that live beneath our feet and discreetly work their magic to fend off the effects of climate change. These microbes are also essential for plant growth enhancement through their roles in nutrient uptake, nitrogen fixation, and synthesis of growth-promoting chemicals. By understanding and managing soil microbial communities, it is possible to improve soil health, soil water-holding capacity, and promote plant growth in agricultural and natural ecosystems. Added to it, these microbes play an important role in biodegradation, bioremediation of heavy metals, and phytoremediation, which in turn helps in treating the contaminated soils. Unfortunately, climate change events affect the diversity, composition, and metabolism of these microbes. Unlocking the microbial potential demands an interdisciplinary endeavor spanning microbiology, ecology, agronomy, and climate science. It is a call to arms for the scientific community to recognize soil microbes as invaluable partners in the fight against climate change. By implementing data-driven land management strategies and pioneering interventions, we possess the means to harness their capabilities, paving the way for climate mitigation, sustainable agriculture, and promote ecosystem resilience in the imminent future.

Melatonin is an indoleamine that was first isolated and identified as a neurotransmitter in animals and proved to be very important in several indispensable biological processes. Scientists have now proved that this molecule is highly conserved among all the species across kingdoms. Though discovered first in animals, it was found in plants with significant physiological roles. The biosynthesis pathways, mode of action and metabolism and the regulatory mechanism of melatonin are continuously being explored. Melatonin exhibits many hormone-like activities in plants. It has significant functions in plant growth and development, such as enhancement of photosynthesis (carbon fixation), reproductive development, seed germination, root development and growth, circadian rhythms, senescence, post-harvest fruit ripening, maintenance of plant tissue structure and function, delay of senescence and responses to biotic and abiotic stresses. Its function also encompasses antioxidant activity. Recognizing its importance in highly diverse biological functions, some scientists mentioned melatonin as an autoregulatory compound and recommended the use of the name ‘Phyto melatonin’.

Melatonin, a hormone known for its role in regulating sleep–wake cycles in mammals, has been found to have diverse functions in horticultural plants. In recent years, research has revealed the involvement of melatonin in various physiological processes in plants, like regulation of growth and development, stress tolerance, and antioxidant defense. Melatonin can augment seed germination, roots, shoot growth, and biomass accumulation in horticultural crops. It also performs a vital role in regulating vegetative and reproductive growth stages, floral transition, and leaf senescence. Melatonin improves stress tolerance in crops by regulating root architecture, nutrient uptake, and ion transport. Additionally, melatonin works like a broad-spectrum antioxidant by scavenging reactive oxygen species and enhancing antioxidant activity. The mechanism of action of melatonin in horticultural plants involves gene expressions, hormone signaling pathways, and antioxidant defense pathways. Melatonin also interacts with other plant growth regulators (PGRs), comprising auxins, cytokinins, and abscisic acid to coordinate various physiological processes in plants. Melatonin has evolved as a versatile chemical entity with diverse functions in horticultural plants, and its potential applications in crop production and stress management are increasingly being explored. This review aims to provide a comprehensive insight into the present state of knowledge about melatonin and its role in horticulturally important plants and identify avenues for further research and practical applications. Further study must be conducted to fully elucidate the mechanisms of melatonin action in crops and to outline effective strategies for its practical use in horticultural practices.

Accelerating land-use change (LUC) in the Nilgiri Hill Region (NHR) has caused its land to mortify. Although this deterioration has been documented, the destruction of buried gem soil has not been reported. Therefore, this study was conducted to assess the impact of LUC on soil-carbon dynamics in the six major ecosystems in the NHR: croplands (CLs), deciduous forests (DFs), evergreen forests (EFs), forest plantations (FPs), scrublands (SLs), and tea plantations (TPs). Sampling was conducted at selected sites of each ecosystem at three depth classes (0–15, 15–30, and 30–45 cm) to quantify the carbon pools (water-soluble carbon, water-soluble carbohydrates, microbial biomass carbon, microbial biomass nitrogen, dehydrogenase, and different fractions of particulate organic carbon). We found that the LUC significantly decreased the concentration of carbon in the altered ecosystems (49.44–78.38%), with the highest being recorded at EF (10.25%) and DF (7.15%). In addition, the effects of the LUC on the aggregate size of the organic carbon were dissimilar across all the aggregate sizes. The relatively high inputs of the aboveground plant residues and the richer fine-root biomass were accountable for the higher concentration of carbon pools in the untouched EFs and DFs compared to the SLs, FPs, TPs, and CLs. The results of the land-degradation Index (LDI) depicted the higher vulnerability of TP (−72.67) and CL (−79.00). Thus, our findings highlight the global importance of LUC to soil quality. Henceforth, the conservation of carbon pools in fragile ecosystems, such as the NHR, is crucial to keep soils alive and achieve land-degradation neutrality.

Plants are a highly advanced kingdom of living organisms on the earth. They survive under all climatic and weather variabilities, including low and high temperature, rainfall, radiation, less nutrients, and high salinity. Even though they are adapted to various environmental factors, which are variable, the performance of a crop will be compensated under sub/supra optimal conditions. Hence, current and future climate change factors pose a challenge to sustainable agriculture. Photosynthesis is the primary biochemical trait of crops that are affected by abiotic stress and elevated CO₂ (eCO₂). Under eCO₂, the C₃ legumes could perform better photosynthesis over C₄ grasses. The associated elevated temperature promotes the survival of the C₄ crop (maize) over C₃ plants. In the American Ginseng, the elevated temperature promotes the accumulation of phytocompounds. Under less water availability, poor transpirational cooling, higher canopy temperatures, and oxidative stress will attenuate the stability of the membrane. Altering the membrane composition to safeguard fluidity is a major tolerance mechanism. For protection and survival under individual or multiple stresses, plants try to undergo high photorespiration and dark respiration, for instance, in wheat and peas. The redox status of plants should be maintained for ROS homeostasis and, thereby, plant survival. The production of antioxidants and secondary metabolites may keep a check on the content of oxidating molecules. Several adaptations, such as deeper rooting, epicuticular wax formation such as peas, and utilization of non-structural carbohydrates, i.e., wheat, help in survival. In addition to yield, quality is a major attribute abridged or augmented by climate change. The nutrient content of cereals, pulses, and vegetables is reduced by eCO₂; in aniseed and Valeriana sp., the essential oil content is increased. Thus, climate change has perplexing effects in a species-dependent manner, posing hurdles in sustainable crop production. The review covers various scientific issues interlinked with challenges of food/nutritional security and the resilience of plants to climate variability. This article also glimpses through the research gaps present in the studies about the physiological effects of climate change on various crops.

Rice–wheat cropping system (RWCS) is considered as the furthermost vital system in the Indo-Gangetic Plains of South-Asia, including India, Pakistan, Bangladesh, and Nepal. Recently, the deficiency of micronutrients like zinc (Zn) has emerged as one of the prime limitations for the sustainability issues of this RWCS in Zn deficient calcareous soils, particularly in India, as a result of the calcareous typic ustifluvents taxonomic nature of the soils. Therefore, a new Zn fertilization approach for soils is very much needed in the intensive RWCS. Thus, a six-year-long investigation was designed with three different modes of Zn application, viz., the application of Zn only in the first year of study, application in alternative years, and application in every year. Four different rates of Zn applications in a hectare of area for a single year, viz., 2.5, 5.0, 7.5, and 10 kg ha⁻¹ year⁻¹, and times of Zn application, viz., only at first year, alternative years, and in each year. The major aims of the study were to determine Zn concentration in soil; yield; and Zn accumulation by wheat crop under different application methods of Zn. From this study, it was found that a large portion of the applied Zn was present in the residual fraction, and it was also revealed that increasing the frequency of Zn application resulted in the increment in the crystalline fraction. Significant correlation of water-soluble and exchangeable Zn (WS+EX-Zn), complexed Zn (COM-Zn), amorphous Zn (AMO-Zn), organic Zn (ORG-Zn), total Zn (TOT-Zn), grain yield, and grain Zn uptake by wheat indicated that these Zn fractions were dominant forms in the soil to be utilized by plants under rice–wheat rotation. Concerning yield and Zn uptake by wheat, it was noted that the Zn application at 10 kg ha⁻¹ in alternate years was the best Zn application method, while application of Zn at 7.5 kg ha⁻¹ in each year also resulted in comparable yield.