Comprehensive evaluation of biostimulants on leaf-level physiology, water use efficiency, and tuber quality in potato (Solanum tuberosum L.) under drought stress

Effect of a foliar-applied biostimulant mixture on winter wheat (Triticum aestivum) under drought stress conditions

Drought is one of the most common problems that can induce stress on crop production. Due to the rising temperatures caused by climate change, drought has become more frequent in many areas. It is crucial for the agricultural sector to look for more solutions on how to protect and increase plant productivity while using fewer chemical fertilisers. Studies show that biostimulants can act as anti-stress solutions, helping plants to mitigate drought stress while being an environmentally friendly option. The aim of this study was to evaluate the effect of different biostimulants on the morphological, physiological and biochemical parameters of winter wheat (Triticum aestivum L.) during stress and recovery periods. In this study, the biostimulants Terra-Sorb, Millerplex, and their mixture were used. Parameters were measured on the last day of the stress period and the last day of the recovery period. The results showed that drought significantly reduced the morphological parameters of winter wheat. Fresh biomass during drought decreased by approximately 39–53% compared with control (p < 0.05). Winter wheat sprayed with the mixture of biostimulants showed the smallest losses, with fresh biomass reduced by 38.85% and the net photosynthetic rate by 75.72% compared with control, indicating the highest tolerance to drought among all treatments. The mixture also maintained higher transpiration than the other treatments. During plant recovery period, biostimulants did not improve plant performance, and the biochemical parameters were not affected (p > 0.05). This study showed the effect of drought on morphological, physiological and biochemical parameters of winter wheat as well as the efficiency of different biostimulants during drought stress period, especially when biostimulants with two different active components were are used in combination.

Foliar Biostimulants Are Associated with Improved Physiological and Antioxidant Status of “Keitt” Mango Under Deficit Irrigation

Mango (Mangifera indica L.) cultivation is expanding into arid regions where high evaporative demand and restricted irrigation frequently constrain tree performance, creating a need for management strategies that reconcile water saving with sustained productivity. The present two-season field study evaluated the responses of “Keitt” mango grown in a hot, sandy environment to three foliar treatments, Ascophyllum nodosum extract (2%), nano-silicon (100 mg L−1), and ascorbic acid (200 mg L−1), under three deficit irrigation regimes (100%, 75%, and 50% of crop evapotranspiration, ETc). Growth, yield, plant–water relations, photosynthetic pigments, oxidative-stress markers, and antioxidant defenses were assessed and integrated through multivariate analysis. Deficit irrigation progressively reduced shoot growth, yield, relative water content, stomatal conductance, and leaf chlorophyll, while elevating proline, malondialdehyde, and hydrogen peroxide. Both A. nodosum and nano-silicon were consistently associated with attenuated responses across all irrigation levels, with higher antioxidant enzyme activity and retention of a disproportionate share of yield under severe deficit, corresponding to an increase in water productivity of up to approximately 31% at 50% ETc. The closely correlated, opposing shifts in growth and oxidative traits indicate associations among water status, photosynthetic characteristics, and antioxidant responses. These findings describe patterns of co-variation and should not be interpreted as evidence of direct causal mechanisms. Overall, these foliar biostimulants, especially A. nodosum, offer a promising, practical means of complementing deficit irrigation in arid mango production.

Interactive Effects of Jasmonic Acid, Triazole Treatments on Some Biochemical, Physiological, Yield-related Attributes of Mini-tuber Potato Cultivar Agria under Drought Stress Conditions

Foliar silicon application enhances maize agronomic performance under drought stress

Drought stress poses a critical threat to maize productivity by impairing physiological processes and yield formation. Silicon (Si) has emerged as a stress-mitigating element due to its ability to improve plant water status, preserve membrane stability, and protect photosynthetic pigments under drought conditions. However, there is a further need to explore the effectiveness of foliar-applied Si in hybrid maize under different drought conditions, especially during the reproductive stage. This pot experiment was conducted during fall 2023 to evaluate the effectiveness of foliar-applied silicon (Si) in mitigating drought-induced damage in hybrid maize. The experiment was arranged in a completely randomized design using a factorial arrangement with three field capacity levels (100%, 80%, and 60% FC) and four silicon concentrations (0, 4, 6, and 8 mM). Drought stress at 60% FC reduced grain yield per plant by 32.7%, thousand-grain weight by 16.3%, relative water content by 23.9%, and chlorophyll a by 46.2% compared with the well-watered control. While foliar application of 8 mM Si alleviated drought effects by increasing grain yield by 30.7%, biological yield by 7.5%, and relative water content by 9.2% compared with untreated plants under 60% FC. Cell membrane injury was reduced by 12.9% with 8 mM Si under severe drought. Significant FC × Si interaction effects were observed for thousand-grain weight, grain yield per plant, biological yield, grain protein content, and grain rows per cob. These findings suggest that, among the tested treatments, foliar application of 8 mM Si was most effective in reducing drought-induced physiological damage and maintaining yield under severe reproductive-stage drought stress.

Salicylic Acid Improves Morpho-Physiological Traits and Biomass of Kale under Drought Stress

Drought stress in agricultural land disrupts the physiological processes, growth, and yield of kale (Brassica oleracea L. var. acephala). This study evaluated the physiological responses, growth, and yield of kale treated with salicylic acid, a potential strategy to enhance plant tolerance to drought stress, in a greenhouse at the Department of Agriculture, Universitas Diponegoro, Semarang. A 4 × 4 factorial experiment was arranged in a Completely Randomized Design (CRD) with three replications. The first factor was drought level (100%, 80%, 60%, and 40% field capacity). The second factor was salicylic acid (SA) concentration 0, 0.75, 1.5, and 2.25 mM). The results indicated that physiological responses (chlorophyll a, chlorophyll b, total chlorophyll, relative water content, and electrolyte leakage) remained largely stable under moderate drought stress (60% FC), whereas plant growth parameters (plant height, leaf number, and leaf area) were reduced by 14.5–20.7% compared with the control (100% FC). At 40% FC, both physiological and growth responses were more severely affected; electrolyte leakage increased markedly, and plant height, leaf area, and dry biomass weight decreased by 24.4%, 47.2%, and 60.5%, respectively, compared with the control (P < 0.05). The best treatment was the application of 1.5 mM salicylic acid, which increased the relative water content by 4.13% and decreased the electrolyte leakage by 34.70% compared to untreated plants (P < 0.05). This concentration was likely more effective due to optimal stomatal regulation, increased antioxidant enzyme activity, and maintained membrane integrity, indicating that 1.5 mM SA has potential as a biostimulant to improve kale water status and membrane stability. However, field validation across locations and seasons is needed before recommending it for dryland farming.

Evaluation of Drought Tolerance in In Vitro potato (Solanum tuberosum L.) cv. Dayang Sumbi Plantlets Using Polyethylene Glycol (PEG) 6000

Potato (Solanum tuberosum L.) is an important food crop whose productivity tends to decline under drought stress conditions. Water deficit limits water uptake, reduces cell turgor pressure, and disrupts photosynthesis, resulting in inhibited plant growth. Development of drought-tolerant potato cultivars can be achieved through in vitro culture using polyethylene glycol (PEG) 6000 as a selective agent that lowers the water potential of the culture medium without causing direct damage to plant cells. This study aimed to evaluate the effect of PEG 6000 on the growth of in vitro potato plantlets of the Dayang Sumbi cultivar and to determine the concentration that could still be tolerated under drought stress conditions. The experiment was conducted at the Botany Laboratory, Faculty of Mathematics and Natural Sciences, Universitas Lampung, using a Completely Randomized Design (CRD) with five PEG 6000 concentrations (0%, 5%, 10%, 15%, and 20%) and five replications. The observed parameters included plantlet survival percentage, plantlet height, number of leaves, and stomatal index. The data were analyzed using analysis of variance (ANOVA) followed by Tukey's Honestly Significant Difference (HSD) test at a 5% significance level. The results showed that all plantlets remained viable, with a 100% survival rate across all PEG 6000 concentrations during the two-week observation period. Significant differences were observed in plantlet height, leaf number, and stomatal index, all of which decreased progressively with increasing PEG 6000 concentration and reached their lowest values at 20% PEG 6000. A PEG 6000 concentration of 10% was found to support the growth tolerance of Solanum tuberosum L. cv. Dayang Sumbi plantlets under in vitro drought stress conditions.