MicroRna268-Mediated Zinc Homeostasis in Rice (Oryza Sativa L.): Enhancing Growth and Yield Under Different Methods and Timing of Zinc Fertilizer Application

Zinc Fertilization Mitigates Boron Toxicity in Citrus: Plant Growth, Tissue Mineral Composition and Antioxidant Enzyme Activity

Boron (B) toxicity severely restricts Citrus growth and productivity in high-B soil and irrigation water environments. Although exogenous Zinc (Zn) has been reported to mitigate B toxicity in plants, the underlying physiological regulation mechanisms—particularly in Citrus—remain incompletely understood. In this study, seedlings of two Citrus species differing markedly in B tolerance—Citrus sinensis (sweet orange, B-tolerant) and C. grandis (sour pomelo, B-sensitive)—were subjected to three boric acid treatments (10, 200, and 400 μM) and five ZnSO4 treatments (0.002, 0.05, 0.1, 0.2, and 0.25 mM) in a fully factorial design over 15 weeks. Comprehensive physiological assessments—including growth parameters, photosynthetic performance, mineral-nutrient profiling (in leaves and roots), and antioxidant enzyme activity—were conducted to decipher the mechanistic basis of Zn-mediated B detoxification. Results showed that 400 μM BA alone triggered severe B toxicity symptoms in the older leaves of C. grandis, whereas 0.25 mM Zn independently led to chlorosis symptoms similar to Fe deficiency in the apical leaves of both Citrus species. Either B or Zn toxicity affected photosynthesis in matured leaves. Exogenous Zn at 0.05–0.20 mM alleviated B toxicity symptoms in B-sensitive C. grandis, yet consistent alleviation of Zn toxicity by excess B was not observed across all measured variables. Severe B toxicity caused a significant reduction in Fe, N, P and Ca contents and a significant increase in Cu and Mn contents in C. grandis roots, yet it only led to a significant reduction in Mn, N, P and Ca contents in C. grandis leaves. Unlike this, B toxic treatments in C. sinensis resulted in a significant reduction in merely Fe content and a significant increase in Cu, Mn, N and K contents in roots, and a significant reduction in Mn and Ca contents in the leaves. Under basal B supply, 0.05–0.20 mM Zn supplementation dose-dependently increased root Zn, Cu and Mn contents as well as leaf Zn and Cu contents in both Citrus species, but concurrently decreased root Fe content and leaf Fe and Ca contents—additionally, in C. grandis, leaf N, P, K and Mg contents were further reduced. Regarding antioxidant responses in C. grandis, B toxicity significantly suppressed leaf CAT activity while enhancing APX and GPX activities. Under B toxicity conditions, 0.2 mM Zn supplement significantly restored CAT activity and suppressed APX and GPX activities. These antioxidant modulations were highly dependent on species identity and treatment combination, and were markedly more pronounced in B-sensitive C. grandis. Collectively, this work clarifies the physiological interplay between Zn and B in Citrus, uncovers divergent adaptive strategies employed by contrasting citrus species under combined B–Zn stress, and provides a mechanistic foundation for optimizing exogenous Zn application to mitigate B toxicity in citrus production.

Response of tomato (Solanum lycopersicum L.) to micronutrients and plant growth regulators with respect to growth, yield and nutrient uptake

A field experiment was conducted during the kharif season of 2024–25 at the College of Horticulture, Bagalkot, to investigate the effects of micronutrients and plant growth regulators (PGRs) on growth, yield and nutrient uptake of tomato (Solanum lycopersicum L.). The experiment was arranged in a randomised block design (RBD) with ten treatments and 3 replications. The treatments consisted of foliar application of micronutrients (zinc, (Zn), iron (Fe), copper (Cu) and boron (B)) and PGRs (gibberellic acid (GA₃) and naphthalene acetic acid (NAA)) in various combinations along with the recommended dose of fertilisers (RDF). The results revealed that the combined application of micronutrients and PGRs significantly enhanced vegetative growth, flowering, yield attributes, fruit quality and nutrient uptake compared to RDF alone. Among the treatments, foliar application of GA₃ and NAA (60 c each) along with zinc sulphate (ZnSO₄), iron sulphate (FeSO₄), copper sulphate (CuSO₄) and boric acid (0.015 % each) recorded the highest fruit yield (74.04 t ha-1), along with improved growth parameters, yield components and quality traits such as total soluble solids (TSS) and ascorbic acid content. This treatment also resulted in higher nutrient uptake and economic returns, with a benefit–cost ratio of 3.19. The study concludes that the integrated foliar application of micronutrients (0.015 %) and PGRs (60 ppm) is an effective strategy to enhance productivity, quality and nutrient uptake of tomato under field conditions.

Phenotypic, hydroponic performance assessment, and expression profiling of triple knockout negative regulator genes in rice (Oryza sativa L.)

Rice is one of the most significant crops consumed daily by individuals. Enhancing and biofortifying rice to augment its nutritional value is a promising strategy for improving public health and tackling the widespread issue of micronutrient deficiencies. This study primarily attempted to evaluate the developed Cas9-free edited lines grown hydroponically with a triple knockout of the negative metal sensor regulator uptake (OsHRZ1, OsHRZ2, and OsLCT1). This result shows that the Cas9-free edited lines’ performance was excellent, with no significant effect on the plant's agronomic performance or yield penalty due to multiplex knockout of genes, in addition to growing under cadmium stress conditions. The protein content of seeds was higher in the Cas9-free edited lines than the protein concentrations observed in the wild type (control/treated), where the protein concentration ranged from 17 to18 mg g−1 FW protein compared to the wild type (normal/treated) (7.24, 7.08) mg g−1 FW, respectively. The concentration varies based on the growth condition under deficient or sufficient Fe/Zn. Photosynthetic rates were increased in Cas9-free edited plants in comparison to wild rice plants, correlating with enhanced agronomic yield parameters and tolerance of cadmium conditions. Rice pollen grain viability and fertility were examined to check the effect of excess iron/zinc on pollen grain viability, fertility, and germination. The expression of genes closely linked to iron, zinc, and cadmium uptake and translocation in rice endosperm was studied. Developed rice lines hold a huge promise to overcome micronutrient malnutrition worldwide.

Physiological and molecular responses of lentil to plant growth-promoting rhizobacteria (PGPR) inoculation and targeted foliar application of melatonin and spermidine under dryland drought stress

Evaluation of Agronomic Biofortification on Yield, Quality and Nutrient Acquisition of Soybean [Glycine max (L.) Merrill] in the Mid-hills of Nagaland

Background: Sulfur (S) and zinc (Zn) are vital nutrients for oilseed crops like soybean, significantly influencing their growth, yield and quality. Sulfur is essential for protein synthesis, enzyme function and chlorophyll formation, which are crucial for the overall health and productivity of the plant. Zinc, on the other hand, plays a critical role in enzyme activation, hormone regulation and protein synthesis. It enhances disease resistance and stress tolerance in soybeans. Methods: During the kharif seasons of 2017 and 2018, a field experiment was carried out at Nagaland University to evaluate the influence of different sulfur and zinc levels on soybean. The treatments consisted of three sulfur levels (0, 20 and 40 kg ha-1) and five zinc levels (0, 5, 10, 15 and 20 kg ha-1) arranged in a factorial randomized block design. Result: The findings showed that the use of 20 kg S ha-1 along with 20 kg Zn ha-1 greatly enhanced parameters for growth, yield attributes, seed quality and nutrient uptake. These findings suggest that balanced application of sulfur and zinc is an effective strategy for enhancing soybean productivity under rainfed conditions.

Lysine-metal complexes modulate nutrient and gene responses in Pb-stressed maize (Zea mays L.).

Lead (Pb) toxicity significantly undermines agricultural productivity and food safety by disrupting plant growth and vital physiological functions, highlighting the urgent need for innovative approaches to enhance nutrient uptake and utilization. In this context, the use of lysine-metal complexes emerges as a crucial strategy, not only mitigating Pb toxicity but also optimizing mineral nutrient acquisition in plants, thereby supporting essential physiological processes and improving overall plant resilience. This study investigated the efficacy of lysine-metal complexes (copper-lysine [Cu-Lys], magnesium-lysine [Mg-Lys], and calcium-lysine [Ca-Lys]) in alleviating Pb-induced stress in maize (Zea mays L.) through the enhancement of growth attributes, photosynthetic efficiency, antioxidant defense, and cellular mechanisms. A pot experiment was conducted at Zayed University, UAE, where Pb was applied at 0, 100, and 200 mg kg-1 soil using Pb(NO3)2, and foliar treatments of Lys-metal complexes (10 mg L-1) were applied weekly, starting 14 days after sowing. The results revealed that Pb stress significantly reduced plant growth, photosynthetic pigments, gas exchange, and biomass, accompanied by increased oxidative stress markers such as hydrogen peroxide and malondialdehyde. However, Lys-metal complexes, particularly copper-lysine complex (Cu-Lys), markedly improved growth, photosynthetic pigments, gas exchange parameters, and antioxidant activities, including the AsA-GSH cycle and enzymatic antioxidants (superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase). Proline accumulation and modulation of cellular fractionation were observed, leading to reduced Pb translocation and enhanced Pb immobilization in the cell wall. Among the treatments, Cu-Lys demonstrated superior effectiveness, followed by magnesium-lysine complex (Mg-Lys) and Ca-Lys. In conclusion, Lys-metal complexes mitigate Pb toxicity by improving physiological and biochemical responses, reducing Pb uptake, and enhancing antioxidant defense mechanisms. These findings highlight the potential of Cu-Lys, Mg-Lys, and Ca-Lys as sustainable strategies to enhance Z. mays resilience in Pb-contaminated environments.