The objective of this study was to evaluate the applicability of soil pH and chlorophyll content as predictive indicators of damage in paddy fields affected by HCl spills, based on causal relationships. Five doses of HCl (e.g., 1, 50, 100, 200, and 500-fold of PNEC) were added to the paddy mesocosm during the rice heading stage. In the 7th week after the acid addition, rice grain quality (e.g., 1000-grain weight and filled grain ratio), soil microbial diversity (e.g., Operational Taxonomic Units (OTUs) and Shannon index), and soluble nutrients (e.g., NH4+, NO3-, SiO2, P2O5, and basic cations) were measured. Causal relationships among variables were analyzed using the Partial Least Square Path Model (PLS-PM). At the dose of 500xPNEC, all rice plants lodged when pH < 4. At 100xPNEC and 200xPNEC, the number of immature grains increased, resulting in a reduction in grain quality of over 18%. At 200xPNEC, the microbial OTUs and the Shannon index decreased by 30%. Notably, the proportion of Planctomycetes, the dominant phylum in the control soil, decreased. The reduction of Planctomycetes led to excessive NH4+ accumulation in the soil, which leads to an undesirable increase of chlorophyll content thereby deteriorating grain quality. The causal relationship suggests that information of soil pH and leaf chlorophyll can aid us in predicting damage for grain quality and microbial diversity.

Agricultural drought significantly affects crop growth and food production, making accurate drought thresholds essential for effective monitoring and discrimination. This study aims to monitor the threshold ranges for different drought levels of winter wheat during three growth periods using a multispectral Unmanned Aerial Vehicle (UAV). Firstly, based on controlled field experiments, six vegetation indices were used to develop UAV optimal inversion models for the Leaf Area Index (LAI) and Soil-Plant Analysis Development (SPAD) during the jointing-heading period, heading-filling period, and filling-maturity period of winter wheat. The results show that during the three growth periods, the DVI-LAI, NDVI-LAI, and RVI-LAI models, along with the DVI-SPAD, RVI-SPAD, and TCARI-SPAD models, achieved the highest inversion accuracy. Based on the UAV-inversed LAI and SPAD indices, threshold ranges for different drought levels were determined for each period. The accuracy of LAI threshold monitoring during three periods was 92.8%, 93.6%, and 90.5%, respectively, with an overall accuracy of 92.4%. For the SPAD index, the threshold monitoring accuracy during three periods was 93.1%, 93.0%, and 92%, respectively, with an overall accuracy of 92.7%. Finally, combined with yield data, this study explores UAV-based drought disaster monitoring for winter wheat. This research enriches and expands the crop drought monitoring system using a multispectral UAV. The proposed drought threshold ranges can enhance the scientific and precise monitoring of crop drought, which is highly significant for agricultural management.

The use of sensor technology is essential in managing fertilization, especially in urban landscape where excessive fertilization is a common issue that can lead to environmental damage and increased costs. This study focused on optimizing nitrogen fertilizer application for Satinleaf (Chrysophyllum oliviforme), a native Florida plant commonly used in South Florida landscaping. Fertilizer with an 8N-3P-9K formulation was applied in six different treatments: 15 g (control), 15 g (15 g twice; T1), 15 g (15 g once; T2), 30 g (15 g twice; T3), 30 g (15 g once; T4), and 45 g (15 g twice; T5). Evaluations of plant growth and nutrient status were conducted at several intervals: baseline (0), and 30, 60, 90, 120, 150, and 180 days post-fertilizer application. Three types of optical sensors-GreenSeeker (TM), SPAD meter, and atLEAF chlorophyll sensor - were used to monitor chlorophyll levels as an indicator of nitrogen content. The study found that the 30 g (15 g twice; T3) treatment was most effective in promoting plant growth and increasing nitrogen content in leaves and soil, while the 45 g (15 g twice; T5) treatment resulted in higher nutrient runoff, indicating potential environmental risks. These findings emphasize the value of using optical sensors for precise nitrogen management in plant nurseries to enhance growth, lower costs, and minimize environmental impact.

Chromium (Cr), a persistent soil pollutant, has detrimental effects on plants and living things, and its contamination in soil increased as a result of human-induced activities. Pakistan suffers from a lack of fresh water supplies; hence most people use metal-containing water and wastewater to irrigate their crops. Exposure to Cr toxicity, the plant reduces their morphological and physiological growth which ultimately decreases crop productivity. The current study was designed to investigate the foliar application of hesperidin (HSP) at varying effluent rates (25, 50, 75, and 100 mg L-1) on wheat growth under tannery wastewater irrigated soil. Cr toxicity caused a change in the concentration of chlorophyll molecules, indicating early signs of stress. Modifications in the ultrastructure of chloroplasts, the elevated activity of chlorophyllase, and the generation of reactive oxygen species were causing the reduction in chlorophyll. Cr stress disrupted total soluble protein concentrations and the activity of antioxidationrelated enzymes and NRA, suggesting the onset of oxidative stress. On the other hand, the application of HSP reduced oxidative damage by improving protein concentration (37%), chlorophyll concentration (37%), and antioxidant enzyme activity such as CAT (65%), SOD (46%), and POD (68%). Furthermore, HSP raised the concentrations of non-enzymatic antioxidant molecules, which may indicate better redox homeostasis and stress tolerance. These molecules include GSH, GSSG, ascorbic acid, flavonoids, phenolics, and anthocyanins. HSP therapy lessened the impact of Cr stress on lipid peroxidation markers. HSP enhanced these measures during the investigation. Cr stress raised the concentrations of total free amino acids and nitrogen oxide and decreased the radical scavenging activity in wheat. Cr stress raised the concentration of all soluble sugars, primarily reducing and non-reducing sugars, whereas the application of HSP strengthened these osmo protectants even more results of the present investigation indicate that exogenous HSP is a feasible and eco-friendly approach to improving plant resistance against Cr toxicity by efficiently reducing the physiological strain and metabolic stress caused by Cr in wheat plants.

The present study aimed to identify and characterize new sources of salt tolerance among 94 rice genotypes from varied geographic origins. The genotypes were divided into five groups based on their morphological characteristics at both vegetative and reproductive stages using salinity scores from the Standard Evaluation System (SES). The experiment was designed as per CRD (Completely Randomized Design) with two sets of salinity treatments for 8 dS/meter and 12 dS/meter, respectively compared with one non-salinized control set. Using a Soil Plant Analysis Development (SPAD) meter, assessments of the apparent chlorophyll content (greenness) of the genotypes were done to comprehend the mechanism underlying their salt tolerance. To evaluate molecular genetic diversity, a panel of 1 K RiCA SNP markers was employed. Utilizing TASSEL 5.0 software, 598 filtered SNPs were used for molecular analysis. Whole-genome association studies (GWAS) were also used to investigate panicle number per plant (pn, tiller number per plant (till), SPAD value (spad), sterility (percent) (str), plant height (ph) and panicle length (pl). It is noteworthy that these characteristics oversee conveying the visible signs of salt damage in rice. Based on genotype data, diversity analysis divided the germplasm groups into four distinct clusters (I, II, III and IV). For the traits studied, thirteen significant marker -trait associations were discovered. According to the phenotypic screening, seven genotypes namely Koijuri, Asha, Kajal, Kaliboro, Hanumanjata, Akundi and Dular, are highly tolerant to salinity stress. The greenness of these genotypes was found to be more stable over time, indicating that these genotypes are more resistant to stress. Regarding their tolerance levels, the GWAS analysis produced comparable results, supporting that salinity -tolerant genotypes having minor alleles in significant SNP positions showed more greenness during the stress period. The Manhattan plot demonstrated that at the designated significant SNP position, the highly tolerant genotypes shared common alleles. These genotypes could therefore be seen as important genomic resources for accelerating the development and release of rice varieties that are tolerant to salinity.