Acetylsalicylic acid increases postharvest longevity of ornamental sunflower inflorescence

Sunflower to be used in ornamental floral arrangements need to be free from damage, and have longer shelf life. The aim of the present study was to evaluate the effect of acetylsalicylic acid (ASA) on the postharvest longevity of ornamental sunflower. Floral stems of the cultivar Vicent’s Choice from Sakata Seed were placed in flasks containing 350 mL of solution containing 0, 200, 400, 600, 800, or 1000 mg of ASA per liter of distilled water. Aspirin® (acetylsalicylic acid) tablets were used as the source of salicylic acid. Grades from 0 to 5 were assigned every day, according to a pre-established criteria for assessing the longevity and quality of the inflorescences. The data were subjected to analysis of variance, Tukey’s test (t = 0.05%), and regression analysis using Sisvar program. Significant differences were observed in the grades from the sixth to the tenth day of treatment, but not in the total longevity. Treatment with 400 mg L-1 of ASA improved the commercial longevity to an average of 9 days, about 4 days more than the control (0 mg L-1). At 400 mg L-1 dose, ASA prolongs the commercial longevity and maintains the postharvest quality of ornamental sunflower stems. However, at the maximum dose used (1000 mg L-1), the evaluated parameters did not show any improvement over the controls.

Postharvest Quality of Cut Zinnia Flowers Cultivated Under Different Irrigation Levels and Growing Seasons

The quality of floral stems depends on a set of pre-harvest factors which can influence their postharvest longevity. Although the identification of visual signs of senescence through scales is decisive in assessing the loss of floral quality in the postharvest period, this scale does not exist for zinnia flowers (Zinnia elegans Jacq.). Thus, the objectives of this study were to evaluate the effect of different irrigation levels and growing seasons on the postharvest longevity of zinnia floral stems; and to determine a senescence scale to assess their durability. Therefore, zinnia plants (cv. “Red California Giant”) were cultivated in pots inside a greenhouse in Seropédica (Rio de Janeiro, Brazil), with a randomized block design, under four irrigation levels (46%, 64%, 75% and 100% of the species’ water requirement) and two cycles (autumn-winter and winter-spring). At the end of each cycle, 48 stems from each treatment were harvested and placed in containers holding 300 mL of supply water. For all irrigation levels and crop cycles, there was an increase in the fresh stem weight on the first days after harvesting and the water absorption rate was higher on the first day of evaluation. The proposed senescence scale allowed us to evaluate the loss of floral quality in the postharvest period. The stems from both cycles had satisfactory results, mainly of commercial longevity and the score 5 on the scale, which represents 100% of the stems’ market value. The main postharvest results of the zinnia floral stems were not influenced by the irrigation levels.

Comparative efficacy of selenate and selenium nanoparticles for improving growth, productivity, fruit quality, and postharvest longevity through modifying nutrition, metabolism, and gene expression in tomato; potential benefits and risk assessment

This study attempted to address molecular, developmental, and physiological responses of tomato plants to foliar applications of selenium nanoparticles (nSe) at 0, 3, and 10 mgl-1 or corresponding doses of sodium selenate (BSe). The BSe/nSe treatment at 3 mgl-1 increased shoot and root biomass, while at 10 mgl-1 moderately reduced biomass accumulation. Foliar application of BSe/nSe, especially the latter, at the lower dose enhanced fruit production, and postharvest longevity, while at the higher dose induced moderate toxicity and restricted fruit production. In leaves, the BSe/nSe treatments transcriptionally upregulated miR172 (mean = 3.5-folds). The Se treatments stimulated the expression of the bZIP transcription factor (mean = 9.7-folds). Carotene isomerase (CRTISO) gene was transcriptionally induced in both leaves and fruits of the nSe-treated seedlings by an average of 5.5 folds. Both BSe or nSe at the higher concentration increased proline concentrations, H2O2 accumulation, and lipid peroxidation levels, suggesting oxidative stress and impaired membrane integrity. Both BSe or nSe treatments also led to the induction of enzymatic antioxidants (catalase and peroxidase), an increase in concentrations of ascorbate, non-protein thiols, and soluble phenols, as well as a rise in the activity of phenylalanine ammonia-lyase enzyme. Supplementation at 3 mgl-1 improved the concentration of mineral nutrients (Mg, Fe, and Zn) in fruits. The bioaccumulated Se contents in the nSe-treated plants were much higher than the corresponding concentration of selenate, implying a higher efficacy of the nanoform towards biofortification programs. Se at 10 mgl-1, especially in selenate form, reduced both size and density of pollen grains, indicating its potential toxicity at the higher doses. This study provides novel molecular and physiological insights into the nSe efficacy for improving plant productivity, fruit quality, and fruit post-harvest longevity.

Selenium-Ethylene Interplay in Postharvest Life of Cut Flowers

Selenium (Se) is considered a beneficial element in higher plants when provided at low concentrations. Recently, studies have unveiled the interactions between Se and ethylene metabolism throughout plant growth and development. However, despite the evidence that Se may provide longer shelf life in ethylene-sensitive flowers, its primary action on ethylene biosynthesis and cause-effect responses are still understated. In the present review, we discuss the likely action of Se on ethylene biosynthesis and its consequence on postharvest physiology of cut flowers. By combining Se chemical properties with a dissection of ethylene metabolism, we further highlighted both the potential use of Se solutions and their downstream responses. We believe that this report will provide the foundation for the hypothesis that Se plays a key role in the postharvest longevity of ethylene-sensitive flowers.

Cerium nitrate and salicylic acid on vase life, lipid peroxidation, and antioxidant enzymes activity in cut lisianthus flowers

Lisianthus is a major cut flower, but it has a short vase life. To prolong postharvest longevity and improve quantitative and qualitative traits of cut lisianthus flowers, an experiment was conducted on the basis of a Completely Randomized Design with eight treatments on 120 flower sprays in three replications. The experimental treatments included salicylic acid (SA) at the rates of 50, 100 and 200 mg L-1, cerium nitrate [Ce(NO3)3] at the rates of 20, 40, 80, and 200 μM, and control (distilled water). The results revealed that the flowers treated with 40 μM Ce(NO3)3 and those treated with 100 mg L-1 SA had the longest vase life of 15.42 and 15.20 days, respectively. Also, these treatments were most effective in improving water uptake, reducing microbial load at the stem end, and enhancing petals’ protein content. The lowest malondialdehyde (18.65 nmol g-1fresh weight) was related to the treatment of 40 μM Ce(NO3)3 and 100 mg L-1 SA. These treatments showed the lowest polyphenol oxidase (PPO) activity, too. The activity of ascorbate peroxidase (APX) and peroxidase (POD) antioxidant enzymes was significantly higher in the flowers treated with 40 μM Ce(NO3)3 and 100 mg L-1 SA. The treatment of 200 mg L-1 SA had negative effects on all the recorded traits. So, it can be concluded that the treatment of cut lisianthus flowers with 40 μM Ce(NO3)3 and 100 mg L-1 SA can prolong their postharvest longevity by reducing lipid peroxidation and increasing the activity of antioxidant enzymes.

The Effect of Nanosilver on Postharvest Longevity of Thalictrum aquilegifolium L. Foliage

<em>Thalictrum aquilegifolium </em>L. ‘Black Stockings,’ with its interesting foliage, is used as a cut greenery. We tested the postharvest longevity of the foliage after different 24-hr conditioning treatments with nanosilver (0, 5, 10, 15, 20 mg dm⁻³) and 20 g dm⁻³ sucrose and compared the results with those obtained using the standard preservative (200 mg dm⁻³ 8-hydroxyquinoline citrate + 20 g dm⁻³ sucrose) and Floralife 200 Clear. The longevity of the foliage and the content of assimilative pigments were evaluated and the functioning of the photosynthetic apparatus (F₀, Fm, Fv/Fm) was analyzed. We found that leaf senescence, as determined by chlorophyll <em>a </em>and carotenoid content after 14 days of holding, was most effectively inhibited by the solution containing 5 mg dm⁻³ nanosilver and sucrose. This solution increased the maximal quantum efficiency of photosystem II (Fv/Fm) in the leaves.