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Ultraviolet-B (UV–B) radiation as an environmental potential elicitor induces the synthesis of plant secondary metabolites. The effects of UV-B radiation on photosynthetic pigments and dry weight, biochemical and molecular features of old and young leaves of Salvia verticillata were investigated. Plants were exposed to 10.97 kJ m−2 day−1 of biologically effective UV-B radiation for up to 10 days. The sampling process was performed in four steps: 1, 5, 10, and 13 days (recovery time) after the start of irradiation. As a result of plant investment in primary and secondary metabolism, the production of phenolic compounds increased, while chlorophyll levels and leaf dry weight (%) declined. Under long-term UV-B exposure, young leaves exhibited the most significant reduction in chlorophyll a and b content and leaf dry weight. The highest level of total phenol (1.34-fold) and flavonoid concentration (2-fold) relative to the control was observed on the 5th day and recovery time, respectively. Young leaves demonstrated the highest amount of phenolic acids in recovery time. Young leaves on the 5th day of the experiment exerted the highest level of antioxidant activity when compared to the control. A positive correlation was observed between antioxidant activity and the amount of phenolic compounds. Regarding the expression of phenylpropanoid pathway genes, UV-B enhanced the expression of phenylalanine ammonia-lyase, tyrosine aminotransferase, and rosmarinic acid synthase with the highest level in young leaves on the 10th day. Overall, young leaves of S. verticillata indicated higher sensitivity to UV-B radiation and developed more tangible reactions to such radiation.

In this study, we tested the exogenous application of phytosulfokine α (PSKα) for delaying the yellowing of broccoli florets during cold storage. Our results showed that the lower yellowing in broccoli florets treated with 150 nM PSKα was probably due to the higher endogenous accumulation of PSKα, leading to the endogenous accumulation of guanosine 3′, 5′-cyclic monophosphate (cGMP). Besides, broccoli florets treated with 150 nM PSKα exhibited a higher accumulation of phenols and flavonoids by triggering gene expression and activities of phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS). Moreover, the higher expression of L‐galactotno‐1,4‐lactone dehydrogenase (GLDH) gene and the lower expression of ascorbic acid oxidase (AAO) gene in broccoli florets treated with 150 nM PSKα may be the reasons for the higher accumulation of ascorbic acid. In conclusion, the exogenous application of PSKα is a promising strategy in delaying the yellowing and preserving the nutritional quality of broccoli florets during cold storage.

To elucidate the physiological, biochemical and hormonal mechanisms of chilling stress mitigated by drought pretreatment, tomato seedlings (Lycopersicon esculentum cv. C.H Falat) were pretreated by 0, 10 and 20% Polyethylene glycol (PEG) for 7 days followed by subjecting to chilling stress at 3 °C for 6 days and 6 h per day. Results showed that PEG-induced drought improved growth rate of tomato seedling subjected to chilling stress and enhanced their antioxidant enzyme activity, abscisic acid (ABA), anthocyanin accumulation, potassium (K+) and proline content compared with the control (0% PEG) at the end of chilling stress period. PEG pretreatment provided significant protection against chilling stress and reduced poly phenol oxidase (PPO) activity, electrolyte leakage (EL) and H2O2 content in root and leaf of chilled seedlings. Moreover, when PEG pretreatment was applied with chilling stress, we observed an alleviation in the growth impeding and a decrease in chilling symptoms as compared to control seedlings. The highest chilling tolerance was induced by application 20% of PEG. In general, the results indicate that PEG-induced drought, by altering in some tolerant responses, could be effectively used to protect tomato’s seedling from the adverse effects of low temperatures stress.

Adaptive neuro fuzzy inference system (ANFIS) and genetic algorithm–artificial neural network (GA-ANN) models were used to predict the effect of methyl jasmonate (at three levels 0, 0.01, and 0.1 mM) and storage time (0, 14, 28, 42, 56, 70, and 84 days) on quality parameters and physiological changes of pomegranate fruits during storage. Methyl jasmonate reduced chilling injury and improved quality characteristics of pomegranates during postharvest storage. The GA-ANN and ANFIS were fed with two inputs of methyl jasmonate and storage time. The results showed that GA-ANN predictions agreed with experimental data and the GA-ANN with 14 neurons in one hidden layer can predict physiological changes and quality parameters of pomegranate (weight loss, pH, chilling injury index, ion leakage, ethylene, respiration, polyphenols, anthocyanins, and total antioxidant activity) with correlation coefficients equal to 0.87. The ANFIS model was trained by a hybrid method and agreement between experimental data an...

In this study, the mechanism by which the exogenous application of 150 nM signaling bioactive peptide phytosulfokine α (PSKα) delays senescence and improves antioxidant nutrient accumulation in strawberry fruit during storage at 4 °C for 18 d was investigated. Results showed that the higher endogenous accumulation of PSKα in strawberry fruit treated with 150 nM PSKα may result from the higher expression of PSK3 and PSK6 genes. Besides, the higher endogenous accumulation of Ca2+ in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher cytosolic accumulation of cGMP, resulting from the triggering of endogenous PSKα signaling pathway, represented by higher expression of PSKR1 gene. Besides, the higher endogenous melatonin accumulation resulting from higher expression of TDC, T5H, SNAT, and ASMT genes in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher endogenous accumulation of Ca2+. Moreover, the higher ABTS and DPPH scavenging capacity in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher accumulation of phenols, flavonoids, and anthocyanins, resulting from higher gene expression and activities of PAL and CHS. Based on our findings, the exogenous application of PSKα could be employed as a beneficial procedure for delaying senescence and improving antioxidant nutrient accumulation in strawberry fruit during cold storage, by triggering endogenous PSKα signaling, promoting endogenous melatonin accumulation, and activating the phenylpropanoid pathway.

In this experiment, we tested the exogenous melatonin (0, 1, 10, 100, and 1000 μM) injection at the light green stage for the regulation of strawberry (Fragaria annanaca cv. Sabrina) fruit ripening. Our results showed that a higher endogenous content of melatonin resulting from higher expressions of TDC, SNAT, T5H, and ASMT in response to 1000 μM melatonin injection may be attributed to an accumulation of H2O2 resulting from a higher expression of NADPH oxidase. Also, a higher endogenous accumulation of ABA (due to a higher expression of NCEDs genes) and a higher accumulation of anthocyanin (due to higher expressions of PAL and CHS genes) may be attributed to a higher expression of the GAMYB gene and a lower expression of SnRK2.6 gene, resulting from the endogenous accumulation of melatonin, involved in the ripening of strawberry fruits. Therefore, our results indicate that the exogenous application of melatonin can accelerate the ripening of strawberry fruits by 2–3 days.

In this study, the effects of postharvest salicylic acid, chitosan and salicyloyl chitosan treatments on chilling injury and nutritional quality of pomegranate fruits during storage at 2 °C for 5 months was investigated. Chilling injury symptoms in pomegranate fruits were manifested by external husk browning and internal segment browning. Alleviation impacts of salicyloyl chitosan treatment on pomegranate fruits chilling injury was higher than salicylic acid and chitosan treatments along, which results to delay external and internal browning and increases in electrolyte leakage. Also, pomegranate fruits treated with salicyloyl chitosan exhibited higher membrane unsaturated/saturated fatty acids (unSFA/SFA) ratio. Higher hydrophilic (H-TAA) and lipophilic (L-TAA) antioxidant capacity in pomegranate fruits treated with salicyloyl chitosan results from higher total phenols, anthocyanins and ascorbic acid accumulation. In addition to nutritional quality, pomegranate fruits treated with salicyloyl chitosan exhibited lower weight loss, respiration rate and ethylene production associated with higher firmness, total soluble solids, and titrable acidity as sensory quality. These results suggest that salicyloyl chitosan treatment can be used as promising strategy not only for alleviating chilling injury by maintaining membrane integrity results from higher unSFA/SFA ratio but also for enhancing antioxidant capacity by total phenols, anthocyanins and ascorbic acid accumulation.

The effect of Aloe vera gel (AVG) and basil seed mucilage (BSM) as coating on qualitative attributes of apricot fruits were studied during storage at 2 °C for 28 days. Fruits coating with AVG and BSM alone or in combination with together significantly reduced weight loss, soluble solid content, respiration rate, ethylene production and ripening index in comparison to the uncoated fruits. Also, in coated fruits the firmness and titratable acidity were higher than control fruits. Application of AVG and BSM efficiently increased antioxidant activity, total phenolic content and ascorbic acid of apricot fruits during cold storage. In evaluation sensory attributes, the panelists did not detect any negative effect of AVG and BSM on flavor and external visual aspect of coated fruits. The results demonstrated that addition of BSM to AVG or their individual application as an edible coatings could be a promising approach to maintain postharvest quality and control physiological process of apricot fruits during cold storage.

Methyl salicylate (MeSA) is a signal molecule in plant responses to biotic and abiotic stress and elicits plant resistance against chilling injury. An experiment was conducted to determine whether MeSA applied at 0, 0.25, 0.5, and 0.75 mM as a seed soak or foliar application would protect cucumber (Cucumis sativus L.) seedlings subjected to chilling at 3°C for 5 days. The MeSA improved growth rate of cucumber seedlings and increased relative leaf chlorophyll and relative water contents by inhibiting malondialdehyde and H2O2 accumulation and increasing proline and antioxidant capacity. MeSA was most effective when applied using the seed soak method at 0.5 and 0.75 mM.

Chilling temperatures lead to numerous physiological disturbances in the cells of chilling-sensitive plants and result in chilling injury and death of tropical and subtropical plants such as watermelon. In this study, the possibility of cold stress tolerance enhancing of watermelon seedling (Citrullus lanatus) by exogenous application of Salicylic acid (SA) was investigated. SA was applied through seed soaking or foliar spray at 0, 0.5, 1 and 1.5 mM concentration. After SA treatment, the seedlings were subjected to chilling 5 h/day at 4°C for 5 days. Statistical analysis showed significant effects of the application methods and SA concentrations on plant growth parameters, photosynthetic pigments, electrolyte leakage, proline and chilling injury index. SA application improved growth parameters and increased chlorophyll content of watermelon seedling subjected to chilling stress and provided significant protection against chilling stress compared to non-SA-treated seedlings. Although two SA application methods improved chilling stress tolerance, seed soaking method provided better protection compared to foliar spray method. SA ameliorated the injury caused by chilling stress via inhibiting proline accumulation and leaf electrolyte leakage. The highest cold tolerance was obtained with 0.5 mM SA application. Results indicate that SA could be used effectively to protect watermelon seedling from damaging effects of chilling stress at the early stages of growth.

Pomegranates were treated by dipping with acetyl salicylic acid (ASA) at three concentrations (0.1, 0.5 and 1.0 mM) immediately after harvest and then stored under chilling temperature for 14, 28, 42, 56, 70 and 84 days at 2 °C plus a subsequent period of 4 days at 20 °C. Control fruit exhibited more chilling injury (CI) symptoms (manifested by pitting and browning) than treated fruit during storage, accompanied by increased softening, ion leakage and respiration rate. The ASA treatments were also effective in maintaining higher contents of nutritive (sugars and organic acids) and bioactive compounds (total phenolics and anthocyanins) and total antioxidant activity (TAA), in both hydrophilic (H-TAA) and lipophilic (L-TAA) fractions. These results suggest that ASA could have potential postharvest application for reducing CI, maintain quality and improve the health benefits of pomegranate fruit consumption by increasing the antioxidant capacity.

Pomegranates were treated after harvest with methyl jasmonate (MeJa) or methyl salicylate (MeSa) at two concentrations (0.01 and 0.1 mM), and then stored under chilling temperature for 84 days. Control fruits exhibited chilling injury (CI) symptoms manifested by pitting and browning, the severity being enhanced as storage time advanced, and accompanied by softening and electrolyte leakage (EL). The CI symptoms were significantly reduced by MeJa or MeSa treatments, without significant differences among treatments or applied dose. In addition, both treatments significantly increased total phenolics and anthocyanins with respect to controls. Hydrophilic (H-TAA) and lipophilic (L-TAA) total antioxidant activity decreased in control arils, but in both MeJa and MeSa treated fruits H-TAA increased while no significant changes occurred for L-TAA. Results would suggest that both MeJa and MeSa have potential postharvest applications in reducing CI, maintaining quality and improving the health benefits of pomegranate fruit consumption by increasing the antioxidant capacity.

The effect of pre-storage application of calcium chloride (CaCl 2 ) on chilling resistance and calcium (Ca) concentration of arils and peel of pomegranate (Punica grauatum) 'Malas Saveh' were determined. The fruits were immersed in distilled water and two CaCl 2 concentrations (135 and 270 mM) for 5 and 10 minutes. The peel Ca concentration of treated fruits significantly increased after 2 months storage, but the arils Ca concentration was not affected with different treatments. Chilling injury (CI) symptoms appeared after 2 months of storage. Postharvest CaCl 2 treatment limited the intense of peel CI symptoms such as browning and pitting but it had no significant effects on internal symptoms especially on segment separating thin layer browning. Treated fruits with 135 and 270 mM CaCl 2 reduced the ion leakage of peel up to 27 and 29%, respectively.

Pomegranate (Punica granatum L.) is rich in bioactive compounds such as phenolics and anthocyanins with proven antioxidant activity in vitro and in vivo. However, pomegranates are considered as perishable commodities with severe storability problems due to their sensitivity to developing chilling injury symptoms when they are stored at low temperatures. These symptoms are manifested by skin browning, surface pitting and desiccation and accompanied by increases in electrolyte leakage leading to quality losses and reduced shelf-life. In this chapter, an overview of the chilling injury incidence and its possible minimization throughout appropriate post-harvest treatments is provided, with special emphasis on some innovative tools such as the natural compounds methyl jasmonate and methyl salicylate. These treatments reduced chilling injury and enhanced the content of bioactive compounds and the total antioxidant activity of the arils along storage leading to fruit with enhanced phytochemicals and increased health-beneficial properties to consumers.

Pomegranate fruit were treated with salicylic acid (SA) at different concentrations (0.7, 1.4 or 2.0 mM), then stored at 2 °C for 3 months to investigate chilling injury (CI). SA treatments, especially at 2 mM concentration, were highly effective in reducing CI and electrolyte leakage in the husk of pomegranate, as well as ascorbic acid (AA) loss compared with that observed in control fruit.

Drought stress is one of the most important limitations of agricultural productions in arid and semi-arid regions including Iran. By applying some of the additives such as super absorbent polymers (SAP) we can achieve good planning for irrigation and optimize use of water resources as an important strategy in these regions. To investigate effects of various levels of SAP and irrigation intervals on quantity and quality properties of sweet pepper in greenhouse of Agriculture Faculty of Ilam University, an experiment was carried out in factorial layout based on complete random blocks design (CRBD) with three replications. The factors were five SAP (0, 0.2, 0.3, 0.4, 0.5 weight percent) and four irrigation levels (5, 7, 9, 11 days). Results of statistical analysis showed SAP, irrigation levels and their interactions had a significant effect on morphological, physiological and biological parameters of sweet pepper. By increasing irrigation intervals and drought stress, growth parameters, yield, chlorophyll and relative water content (RWC) of leaf were reduced and total soluble solids (TSS) electrolytes leakage and proline content increased. In this study, SAP application reduced prolonged irrigation effects on pepper by increasing growth rate, yield, leaf chlorophyll content and RWC and by reducing TSS, electrolyte leakage and proline accumulation. The results of this study showed that SAP can store and absorb considerable water and reduce negative effects of water shortage on plants.

Oxalic acid at three concentrations (2, 4, and 6 mM) was applied by dipping to pomegranate fruits of cv. Mollar de Elche, which were then stored for 84 days at 2 degrees C. Pomegranate is a chilling-sensitive fruit and, thus, control fruits exhibited chilling injury (CI) symptoms after long-term storage at 2 degrees C that were accompanied by increased respiration rate, weight loss, and electrolyte leakage (EL). The CI symptoms were significantly reduced by oxalic acid treatment, especially for the 6 mM concentration. In addition, control pomegranates showed significant reduction in the content of total phenolics and ascorbic acid as well as in total antioxidant activity (TAA), in both hydrophilic (H-TAA) and lipophilic (L-TAA) fractions. The application of oxalic acid led to lower losses of total phenolics and significant increase in both ascorbic acid content and H-TAA, whereas L-TAA remained unaffected. Thus, oxalic acid could be a promising postharvest treatment to alleviate CI and increase antioxidant potential.