Alleviation of Copper-Induced Stress in Pea (Pisum sativum L.) through Foliar Application of Gibberellic Acid

Simple Summary

Phytohormones are key regulators of several stages of plant growth and development as well as provide the regulatory response against various heavy metals stresses by mediating physio-morphological responses and enzymatic activities. The current study evaluated the effects of gibberellic acid (GA₃) foliar applications on the performance of pea grown either in Cu-contaminated (Cu+) and non-contaminated (Cu−) soil. GA₃ was applied exogenously (0, 10, 50, and 100 mg·L⁻¹) on 15-days-old plants, and the results show that the increasing concentration of GA₃ buffered the phytotoxic effects of Cu, coupled with an increase in plant growth and physiological variables. The results also showed that foliar-applied GA₃ up to 100 mg·L⁻¹ alleviated the oxidative stress, as inferred from the lower concentrations of malondialdehyde (MDA) and H₂O₂, which mirrored the increased activity of antioxidant enzymes, i.e., superoxide dismutase, peroxidase, and catalase. In addition, enhanced growth, physiology, and enzymatic activities were also observed in pea plants sprayed with GA₃ up to 100 mg·L⁻¹ in Cu− soil. Overall, the foliar application of GA₃ boosted phytoextraction of Cu from the soil and alleviated the oxidative stress in pea plants grown in Cu-polluted soil.

Abstract

Copper (Cu) is an essential metal for plants. However, its excess in soil can adversely affect plant metabolism. The current study evaluated the effects of gibberellic acid (GA₃) foliar applications on the performance of pea plants grown either in Cu-contaminated (Cu+) and non-contaminated (Cu−) soil. GA₃ was sprayed (0, 10, 50, and 100 mg·L⁻¹) on 15-days-old plants. The results showed that the increasing concentration of GA₃ buffered the phytotoxic effects of Cu and enhanced plant growth, photosynthesis, and leaf chlorophyll content. Foliar-sprayed GA₃ up to 100 mg·L⁻¹ alleviated the oxidative stress, as inferred from the lower concentrations of MDA and H₂O₂ (33.3 µmol·g⁻¹ and 182 µmol·g⁻¹, respectively), and boosted the activity of superoxide dismutase (64.4 U·g⁻¹·FW), peroxidase (122.7 U·g⁻¹·FW), and catalase (226.3 U·g⁻¹·FW). Interestingly, GA₃ promoted Cu accumulation in different plant parts when compared to untreated plants, likely due to increased photosynthetic and transpiration rates. Overall, foliar application of GA₃ promoted phytoextraction of Cu and alleviated the oxidative stress in pea plants grown in Cu+ soil.

Mineral Biofortification of Vegetables as a Tool to Improve Human Diet

Vegetables represent pillars of good nutrition since they provide important phytochemicals such as fiber, vitamins, antioxidants, as well as minerals. Biofortification proposes a promising strategy to increase the content of specific compounds. As minerals have important functionalities in the human metabolism, the possibility of enriching fresh consumed products, such as many vegetables, adopting specific agronomic approaches, has been considered. This review discusses the most recent findings on agronomic biofortification of vegetables, aimed at increasing in the edible portions the content of important minerals, such as calcium (Ca), magnesium (Mg), iodine (I), zinc (Zn), selenium (Se), iron (Fe), copper (Cu), and silicon (Si). The focus was on selenium and iodine biofortification thus far, while for the other mineral elements, aspects related to vegetable typology, genotypes, chemical form, and application protocols are far from being well defined. Even if agronomic fortification is considered an easy to apply technique, the approach is complex considering several interactions occurring at crop level, as well as the bioavailability of different minerals for the consumer. Considering the latter, only few studies examined in a broad approach both the definition of biofortification protocols and the quantification of bioavailable fraction of the element.

Scion and Rootstock Differently Influence Growth, Yield and Quality Characteristics of Cherry Tomato

Grafting is a valuable tool for managing problems of tomato soil-borne pathogens and pests, but often generates unpredictable effects on crop yield and product quality. To observe these rootstocks-induced changes, experimental designs including many rootstock-scion combinations are required. To this end, a greenhouse experiment was conducted on 63 graft combinations, involving seven cherry tomato scions grouped in large, medium and small-fruited, and eight rootstocks with different genetic backgrounds (crosses between Solanum lycopersicum and S. habrochaites or S. peruvianum or S. pimpinellifolium, plus an intraspecific hybrid), using ungrafted controls. The response of the graft partners was firstly analyzed individually using the environmental variance (σ²_E), then by grouping them by classes. When analyzed individually, the scion genotype influenced fruit L*, b*, shape index, total soluble solids (TSS) and its ratio with tritatable acidity (TSS/TA), whereas plant growth and yield were unpredictable. After clustering the graft partners, some of these responses were attributable to the imposed classes. The S. habrochaites-derived hybrids maximized plant biomass, unlike the S. pimpinellifolium ones. Both classes reduced fruit biomass in small- and medium-fruited scions (by 11 and 14%, respectively). The S. habrochaites and S. peruvianum hybrids reduced a* and TSS, whereas promoted TA. L-ascorbic acid was reduced by grafting (from -23 to -45%), in the S. pimpinellifolium group too, indicating, even in low vigor rootstocks, a dilution effect worsening this nutraceutical trait of tomatoes.

Celery (Apium graveolens L.) Performances as Subjected to Different Sources of Protein Hydrolysates

The vegetable production sector is currently fronting several issues mainly connected to the increasing demand of high quality food produced in accordance with sustainable horticultural technologies. The application of biostimulants, particularly protein hydrolysates (PHs), might be favorable to optimize water and mineral uptake and plant utilization and to increase both production performance and quality feature of vegetable crops. The present study was carried out on celery plants grown in a tunnel to appraise the influence of two PHs, a plant-derived PH (P-PH), obtained from soy extract and an animal PH (A-PH), derived from hydrolyzed animal epithelium (waste from bovine tanneries) on yield, yield components (head height, root collar diameter, and number of stalks), mineral composition, nutritional and functional features, as well as the economic profitability of PHs applications. Fresh weight in A-PH and P-PH treated plants was 8.3% and 38.2% higher, respectively than in untreated control plants. However, no significant difference was found between A-PH treated plants and control plants in terms of fresh weight. Head height significantly increased by 5.5% and 16.3% in A-PH and P-PH treated plants, respectively compared with untreated control (p ≤ 0.05). N content was inferior in PHs treated plants than in untreated control. Conversely, K and Mg content was higher in A-PH and P-PH treated plants as compared to the untreated ones. Furthermore, A-PH and P-PH improved ascorbic acid content by 8.2% and 8.7%, respectively compared with the non-treated control (p ≤ 0.001). Our results confirmed, also, that PHs application is an eco-friendly technique to improve total phenolic content in celery plants. In support of this, our findings revealed that animal or plants PH applications increased total phenolics by 36.9% and 20.8%, respectively compared with untreated plants (p ≤ 0.001).

Effect of Seed Priming with Potassium Nitrate on the Performance of Tomato

The seed industry and farmers have challenges, which include the production of poor quality and non-certified tomato seed, which ultimately results in decreased crop production. The issue carefully demands pre-sowing treatments using exogenous chemical plant growth-promoting substances. Therefore, to mitigate the above-stated problem, a series of experiments were conducted to improve the quality of tomato seeds (two cultivars, i.e., “Sundar” and “Ahmar”) and to enhance the stand establishment, vigor, physiological, and biochemical attributes under growth chamber and greenhouse conditions by using potassium nitrate (KNO3) as a seed priming agent. Seeds were imbibed in 0.25, 0.50, 0.75, 1.0, and 1.25 KNO3 (weight/volume) for 24 h and then dried before experiments. The results of growth chamber and greenhouse screening show that experimental units receiving tomato seeds primed with 0.75% KNO3 in both cultivars performed better as compared to other concentrations and nonprimed control. Significant increase in final emergence (%), mean emergence time, and physiological attributes were observed with 0.75% KNO3. Collectively, the improved performance of tomato due to seed priming with 0.75% KNO3 was linked with higher activities of total soluble sugars and phenolics under growth chamber and greenhouse screening.