Lead (Pb) toxicity impairs the growth, yield, and biochemical traits of rice, making it essential to mitigate Pb stress in soil and restore its growth and production. This study investigated the potential of ascorbic acid-coated quantum dots (AsA-QDs) in alleviating Pb stress in two rice cultivars, Japonica (JP-5) and Indica (Super Basmati), grown in pots under Pb stress (50 mg/kg as lead chloride) with AsA-QD suspensions (50 ppm and 100 ppm) as treatments. The synthesized AsA-QDs were characterized by zeta potential (-14.4 mV), particle size (472.3 nm, PDI 0.745), UV-Vis absorption peak (240 nm), FT-IR analysis revealing functional groups (carboxylic acid and alkene), and TEM showing spherical morphology (average size 9.43 nm). Pb stress reduced key traits in JP-5, including tillers per plant (11.11 %), grain yield (18.22 %), kernel weight (18.22 %), protein (40.19 %), phenolic content (59.66 %), and antioxidant capacity (17.75 %), while 50 ppm AsA-QDs improved these by 33.33 %, 5.73 %, 2.03 %, and 13.19 %, respectively. Similarly, Pb stress reduced plant height, T/P, biomass yield (BY), GY, TKW, total sugars, reducing sugars, non-reducing sugars, starch, proteins, and TPC in Super Basmati by 19.76 %, 21.43 %, 11.01 %, 11.01 %, 7.52 %, 38.09 %, 7.24 %, 13.96 %, 11.97 %, and 40.39 %, respectively, while PbQD1 improved these traits by 14.29 %, 15.49 %, 9.25 %, 109.52 %, 8.31 %, 31.72 %, 25.91 %, and 7.075 %, respectively. The findings demonstrate that AsA-QDs effectively mitigate Pb toxicity by reducing oxidative stress, enhancing growth parameters, and restoring yield components, establishing them as a promising nanomaterial for sustainable crop resilience under Pb stress.

Ascorbic acid (ASC) is a molecule naturally synthesized in plant cells, protecting against abiotic stresses by reducing reactive oxygen species (ROS), which cause oxidative damage. Aluminum (Al) toxicity is the major limiting factor on crop productivity in acidic soils, increasing ROS within cells and impairing the growth and development of plants. Exogenous antioxidant applications are an effective strategy to promote tolerance to abiotic stress. The objective was to evaluate the effect of foliar ASC applications (0, 50, 100, 200, and 400 mg L-1 ASC) and their interaction with Al toxicity (0, 400 mu M Al) in Star, an Al-sensitive cultivar of highbush blueberry. Significant increases of 1.6-fold in growth were observed in roots and leaves under treatment with 200 mg L-1 ASC. In the same treatment, increased pigments and antioxidant activity (similar to 1.2- to 2.3-fold) were observed concomitant with reduced lipid peroxidation. Positive correlations between organic acid exudation, the ASC/DHA ratio, and calcium levels were observed, whereas a negative correlation between lipid peroxidation and dehydroascorbate (DHA) was observed. Foliar ASC application also increased the ASC/DHA ratio in leaves and enhanced 2.2-fold organic acid exudation in the 200 mg L-1 ASC treatment. The results suggest that foliar ASC applications improved redox balance and underscore the potential of ASC as a practical solution to enhance resilience in Al-sensitive plants.

Drought stress induces a range of physiological changes in plants, including oxidative damage. Ascorbic acid (AsA), commonly known as vitamin C, is a vital non-enzymatic antioxidant capable of scavenging reactive oxygen species and modulating key physiological processes in crops under abiotic stresses like drought. Chickpea (Cicer arietinum L.), predominantly cultivated in drought-prone regions, offers an ideal model for studying drought tolerance. We explored the potential of AsA phenotyping to enhance drought tolerance in chickpea. Using an automated phenomics facility to monitor daily soil moisture levels, we developed a protocol to screen chickpea genotypes for endogenous AsA content. The results showed that AsA accumulation peaked at 30% field capacity (FC)-when measured between 11:30 am and 12:00 noon-coinciding with the maximum solar radiation (32 degrees C). Using this protocol, we screened 104 diverse chickpea genotypes and two control varieties for genetic variability in AsA accumulation under soil moisture depletion, identifying two groups of genotypes with differing AsA levels. Field trials over two consecutive years revealed that genotypes with higher AsA content, such as BDNG-2018-15 and PG-1201-20, exhibited enhanced drought tolerance and minimal reductions in yield compared to standard cultivars. These AsA-rich genotypes hold promise as valuable genetic resources for breeding programs aimed at improving drought tolerance in chickpea.

Red rice ( Oryza glaberrima L.) is a main food ingredient with some special characteristics and health benefits; therefore, enhancing its grain yield is necessary. However, the limited fertile land causes cultivation in the sub-optimal land, such as saline soil. Saline stress can cause damage to plant cells; hence, it is vital to apply exogenous antioxidants that can act as osmoprotectants. The presented study sought to determine the physiological characteristics of red rice under salinity stress conditions with ascorbic acid applications. The study commenced in a factorial separate plot design (SPD) with three features. The salinity levels (3-4 and >4-5 mho/cm) comprised the main plots, red rice cultivars (Inpari 24, Inpari 7, Pamelen, and MSP17) in the subplots, with the ascorbic acid concentrations (0, 500, 1000, and 1500 ppm) kept in the sub-sub-plots. The results showed that the studied red rice cultivars differed in responses to ascorbic acid concentrations under saline soil conditions. Cultivar MSP17 was the most tolerant genotype to salinity stress compared with the three other red rice cultivars based on physiological attributes. Applying ascorbic acid improved red rice genotypes' physiological characteristics (especially chlorophyll content and nutrient uptake) under saline stress conditions.

Biostimulants such as ascorbic acid, known as vitamin C, have been reported to have numerous positive roles in plant tolerance to abiotic stresses. However, little is known about the biostimulant effects of ascorbic acid on alfalfa (Medicago sativa). Accordingly, a pot experiment was conducted to investigate the effects of 1 mM ascorbic acid, applied as foliar spray, on the salt tolerance of a Moroccan alfalfa population Demnate 201. One month-old M. sativa seedlings were exposed to 200 mM NaCl for four weeks with or without 1 mM of exogenous ascorbic acid treatment. The results showed that salinity stress significantly (p < 0.001) reduced plant biomass, disturbed photosynthesis-related parameters and induced oxidative stress. However, ascorbic acid foliar spray counteracted the observed negative effects of salinity. It significantly (p < 0.001) improved plant growth and photosynthetic parameters. Besides, stress indicators, including Na+ in shoot and root, hydrogen peroxide and electrolyte leakage, were significantly reduced by 42%, 29%, 12% and 34%, respectively, in treated and salt-stressed alfalfa plants. Interestingly, the decrease in oxidative stress markers was positively correlated to the ability of ascorbic acid to induce the accumulation of flavonoids and to increase the antioxidant activity of guaiacol peroxidase. Furthermore, compatible solutes, such as proline and soluble sugars, were found higher especially in salt-stressed alfalfa plants treated with 1 mM ascorbic acid. Our findings showed that ascorbic acid supply could be an eco-friendly and sustainable technique to mitigate the toxic effect of salt and could improve alfalfa forage production when grown in salt-affected soils.

Pea (Pisum sativum L.), a globally cultivated leguminous crop valued for its nutritional and economic significance, faces a critical challenge of soil salinity, which significantly hampers crop growth and production worldwide. A pot experiment was carried out in the Botanical Garden, The Islamia University of Bahawalpur to alleviate the negative impacts of sodium chloride (NaCl) on pea through foliar application of ascorbic acid (AsA). Two pea varieties Meteor (V1) and Sarsabz (V2) were tested against salinity, i.e. 0 mM NaCl (Control) and 100 mM NaCl. Three levels of ascorbic acid 0 (Control), 5 and 10 mM were applied through foliar spray. The experimental design was completely randomized (CRD) with three replicates. Salt stress resulted in the suppression of growth, photosynthetic activity, and yield attributes in pea plants. However, the application of AsA treatments effectively alleviated these inhibitory effects. Under stress conditions, the application of AsA treatment led to a substantial increase in chlorophyll a (41.1%), chl. b (56.1%), total chl. contents (44.6%) and carotenoids (58.4%). Under salt stress, there was an increase in Na+ accumulation, lipid peroxidation, and the generation of reactive oxygen species (ROS). However, the application of AsA increased the contents of proline (26.9%), endogenous AsA (23.1%), total soluble sugars (17.1%), total phenolics (29.7%), and enzymatic antioxidants i.e. SOD (22.3%), POD (34.1%) and CAT (39%) in both varieties under stress. Salinity reduced the yield attributes while foliarly applied AsA increased the pod length (38.7%), number of pods per plant (40%) and 100 seed weight (45.2%). To sum up, the application of AsA alleviated salt-induced damage in pea plants by enhancing photosynthetic pigments, both enzymatic and non-enzymatic activities, maintaining ion homeostasis, and reducing excessive ROS accumulation through the limitation of lipid peroxidation. Overall, V2 (Sarsabz) performed better as compared to the V1 (Meteor).