Effect of Freezing Stress on Lipid Peroxidation and Antioxidant Enzyme Activities of Olive cvs. ‘Fishomi’ and ‘Roughani’

Changes in freezing injury percentage, lipid peroxidation (malonaldehyde formation), antioxidant enzymes activity and proline content were monitored in the leaves of olive cvs. ‘Fishomi’ and ‘Roughani’ under different freezing temperatures (-5, -10, -15 and -20°C for 10 h). The results showed that freezing injury (determined by electrolyte leakage analysis) and malonaldehyde (MDA) content of cv. ‘Fishomi’ were significantly lower than of cv. ‘Roughani’ ones. The activities of peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and polyphenol oxidase (PPO) enzymes of cv. ‘Fishomi’ were signifi cantly higher than those of cv. ‘Roughani’. However, superoxide dismutase (SOD) activity of cv. ‘Roughani’ was higher than of cv. ‘Fishomi’. The proline accumulated in leaves of cv. ‘Fishomi’ was significantly higher than of cv. ‘Roughani’ during freezing stress. The results demonstrated that freezing injury percentage was positively correlated with ion leakage percentage and MDA content in both cultivars. In contrast, SOD, APX and CAT activities and also proline content were negatively correlated with freezing injury percentage. There was a significant negative correlation between PPO activity and freezing injury in cv. ‘Fishomi’. It can be concluded that the lower freezing injury percentage, ion leakage, and MDA content followed by the higher antioxidant enzyme activates as well as proline content in cv. ‘Fishomi’ is a consequence of more effective protective mechanisms

Assessment of New Kiwifruit Genotypes (Actinidia chinensis (A.Chev.) A.Chev.) From Open Pollination by Molecular Markers and Phenotypic Traits

Molecular markers are useful tool to study genetic diversity and the relationship between genotypes. The evaluation of genetic diversity in species is a start step for breeding program. In this study, molecular markers were used to determine diversity and genetic relationships of 120 kiwifruit genotypes. During two consecutive growing seasons, thirty-two discretional morphological traits were studied by the International Union for the Protection of New Varieties of Plants (UPOV) in new kiwifruit genotypes. Average value of polymorphism per primer was 95.1%. Polymorphism information content values for all the primers used ranged from 0.32 to 0.41. High levels of polymorphism were found for all marker systems. Dendrogram generated using unweighted pair group method with arithmetic cluster analysis based on Jaccard’s similarity coefficient and dendrogram generated using Neighbor-joining cluster analysis accessions were separated 120 genotypes into 11 and 5 groups, respectively. For all markers, 171 marker–trait associations were found with the GLM, the significance criteria defined for the traits only at the P≤0.01 level. This study results provide useful genetic information about new kiwifruit genotypes of Iran and indicate that the use of new kiwifruit genotypes in breeding program could be useful for generating new cultivars with novel characteristics

Assessment of New Kiwifruit Genotypes (Actinidia chinensis (A.Chev.) A.Chev.) From Open Pollination by Molecular Markers and Phenotypic Traits

Molecular markers are useful tool to study genetic diversity and the relationship between genotypes. The evaluation of genetic diversity in species is a start step for breeding program. In this study, molecular markers were used to determine diversity and genetic relationships of 120 kiwifruit genotypes. During two consecutive growing seasons, thirty-two discretional morphological traits were studied by the International Union for the Protection of New Varieties of Plants (UPOV) in new kiwifruit genotypes. Average value of polymorphism per primer was 95.1%. Polymorphism information content values for all the primers used ranged from 0.32 to 0.41. High levels of polymorphism were found for all marker systems. Dendrogram generated using unweighted pair group method with arithmetic cluster analysis based on Jaccard’s similarity coefficient and dendrogram generated using Neighbor-joining cluster analysis accessions were separated 120 genotypes into 11 and 5 groups, respectively. For all markers, 171 marker–trait associations were found with the GLM, the significance criteria defined for the traits only at the P≤0.01 level. This study results provide useful genetic information about new kiwifruit genotypes of Iran and indicate that the use of new kiwifruit genotypes in breeding program could be useful for generating new cultivars with novel characteristics

Acer velutinum Bioss. (velvet maple) seedlings are more tolerant to water deficit than Alnus subcordata C.A. Mey. (Caucasian alder) seedlings

Drought stress is a major environmental factor limiting plant growth. Selection of drought-tolerant plants is of critical importance in vegetation restoration and forestation programs. Alnus subcordata and Acer velutinum are two valuable, dominant, and endemic species in the Hyrcanian forests. There are fast-growing species and significant diffuse-porous hardwood in afforestation and reforestation. One-year old seedlings of both species were exposed to four water shortage treatments (100, 75, 50 and 25% of field capacity (FC) chosen as control, mild, moderate, and severe) for 12 weeks. Thereafter, their morphological characteristics such as height and basal area, total and organs biomass (root, stem, and leaf), leaf area (LA), specific leaf area (SLA), leaf area ratio (LAR), as well as physiological and biochemical characteristics such as relative water content (RWC), content of chlorophyll, free proline and malondialdehyde (MDA), and superoxide dismutase (SOD) and peroxidase (POD) activity were measured. The results showed that when exposed to reduced water availability, plants’ height, basal diameter, total and organs biomass, LA, LAR, RWC and chlorophyll content decreased, but their proline concentration, MDA content, SOD, and POD activity increased in both species. The root to shoot ratio (R/S) and root mass ratio (RMR) increased at 50 and 25% FC treatments in A. subcordata, whereas no significant difference was found in A. velutinum under drought treatments. SLA increased significantly at 50% FC in A. velutinum and decreased in A. subcordata under drought treatments compared to control treatment. A. velutinum showed more proline content, RWC, POD, and lower increase in MDA content than A. subcordata under moderate treatment. Therefore, A. velutinum appears to possess a better mechanism to cope drought stress. The drought tolerance of A. velutinum may enhance its potential for climatic adaptations under drier conditions with the ongoing climatic change

Influence of post-véraison water deficit on berries yield and quality of three table grape cultivars

In order to investigate the effect of regulated deficient irrigation (RDI) on some quantitative and qualitative characteristics of the three commercial grapevine cultivars (i.e. Keshmeshi, Sahebi and Sharabi), an experiment was set in split plot arranged in an RCBD design with three replications. In this experiment, irrigation treatments including 100 (as control), 80%, 60% and 40% crop evapotranspiration (ETc) were implemented in a period between onset of berries color change (véraison) to harvest of fruits. At the end of experimental period, some traits such as berry weight, berry length, berry diameter and cluster weight as well as some fruit quality traits such as total soluble solids (TSS), titratable acidity (TA), flavonoids, anthocyanin, total phenol, and total antioxidant capacity were measured. The results of this experiment revealed that effect of RDI at different levels on yield, berry and cluster weight, berry length and diameter, TSS, TA, anthocyanin, phenol, and flavonoid was significant. Also, there was no significant difference between control and 80% ETc in terms of yield, berry diameter, TSS, and TA; and these treatment enhanced total phenol, anthocyanin and antioxidant activity in the three cultivars. In both years of experiment, RDI remarkably enhanced anthocyanin, flavonoids, antioxidant activity and phenolic concentration. Overall, the results indicated that 80% ETc might be sufficient to gain adequate yield in Keshmeshi, Sahebi and Sharabi without undermining the quality of fruit

Effect of Foliar and Soil Application of Humic Acid on Quantity and Quality of Pomegranate Fruit cv. 'Malas-E- Saveh

Humic acid, as an organic acid obtained from humus and organic sources without any environmental destructive effects, is used in the production of horticultural crops. In this study, the effect of foliar and soil application of humic acid treatment (as Humix 95, contains 68% humic acid, 12% fulvic acid and 13-15% potassium) at different concentrations (0, 1.7, 3.4 and 5.1 g pure humic acid per tree at each time) on quantity and quality of pomegranate fruit cv. Malas-e-Saveh performed in the complete randomized block design with three replications. Humic acid is used at pre-flowering, 30 and 60 days after fruit set. The results showed that humic acid treatment increased total fruits per tree, dry matter of aril, fresh weight of aril, aril/peel ratio, total phenolic and flavonoids content and antioxidant activity in compared with control. However, sunburn damage, cracking, aril paleness and fresh weight of peel were significantly lower than control fruits. While, mean fruit weight, total soluble solids (TSS), Titratable acidity (TA), TSS/TA and total anthocyanins content were not affected by humic acid treatment. Overall, humic acid application increased marketable fruits. According to these results, foliar application of humic acid was more effective in the improving quantitative properties and antioxidant activity of pomegranate fruits

Effects of combined Red and Blue light spectra as supplemental light on yield and fruit quality of sweet pepper

Purpose: The use of supplementary light in regions with low natural sunlight is necessary to fulfill the increasing consumer requests for fresh vegetables. This study aimed to investigate the effect of different combinations of red and blue LEDs on yield and quality of greenhouse-grown sweet pepper (Capsicum annuum L.) fruits during the growth period. Research method: The experiments were conducted in Rasht, Iran as split plots in the form of a completely randomized design in three repetitions (four plants per plot) on two cultivars of sweet pepper (Padra and Shadlin). With the appearance of the first flower buds, plants were exposed to different light treatments including: three combinations of red (R) and blue (B) LEDs (T1:R8B1, T2:R7B2, and T3:R6B3), with a same intensity of 200 μmolm-2s-1 as supplement light to the natural light, together with natural light as control treatment (CT). Sweet pepper fruits were harvested weekly over 27 weeks and fruit yield and quality were assessed. Findings: Supplemental light using LEDs significantly increased yield and fruit quality parameters (except titratable acidity and maturity index) compared to the control. Marketable yield was differed among the light treatments and plants exposed to T3 showed the highest marketable yield (14.58 kg/m2). The effect of supplemental light on total yield was more detectable when the average daily light integral was the lowest (for example, the difference between T3 and the control treatment in January was 1.27 kg/m2, while this difference was 0.68 kg/m2 in June). No significant difference was observed between cultivars and T3 was the best treatment in most parameters. Research limitations: No limitations were found. Originality/Value: In the northern regions of Iran, even in the months that do not seem to have light limitations, the use of supplementary light is recommended to increase the yield of sweet peppers in the greenhouse

Effects of Regulated Deficit Irrigation and Superabsorbent Polymer on Fruit Yield and Quality of \u27Granny Smith\u27 Apple

Water resource limitation has caused increasing interest in changing irrigation strategy to improve water use efficiency. In this study, effect of regulated deficit irrigation (RDI) (75 and 50% ETC) in combination with different concentration of superabsorbent polymer (SAP) (0, 100, 200 and 300 g/tree) on fruit yield and quality of \u27Granny Smith\u27 apple was investigated during two consecutive growing seasons. The tree irrigated with 100 ETC was used as control. No significant difference was found between control and RDI and SAP treatments for apple fruit yield. But in the second year of the experiment, apple trees treated with 200 g/tree superabsorbent showed by 15% greater fruit weight. The fruit soluble solid content (SSC) was significantly affected by irrigation regimes and superabsorbent polymer. The highest SSC was found in RDI50 in two years and 200 g/tree superabsorbent in the first year. In the first season, titratable acidity (TA) was significantly affected by SAP levels. The apple trees that received 300 g/tree of SAP, had the highest content of TA in the first season. No significant difference was observed among treatments regarding dry matter percentage and firmness. Total phenolic content of apple fruits was significantly affected by both RDI and SAP treatments in both seasons. In each level of SAP application, by reducing RDI percent total phenolic content increased. The highest phenolic content was found when the trees were treated with 50% RDI with and without SAP treatment

Inhibition of Polyphenol Oxidases and Peroxidase Activities in Green Table Olives by some Anti-browning Agents

Almost, all table olive cultivars are susceptible to the formation of brown spots due to mechanical damage during harvesting and processing. Therefore, application of some anti-browning agents might be an effective strategy to minimize unfavourable effects of enzymatic browning in green table olives. The aim of this study was to assess the effect of ascorbic acid (AA), citric acid (CA), oxalic acid (OA), 4-hexylresorcinol (HR) and sodium hexametaphosphate (NaHMP) on reducing enzymatic browning of four green table olive cultivars (\u27Mari\u27, \u27Shengeh\u27, \u27Manzanilla\u27 and \u27Zard\u27) fruit. The results showed that \u27Mari\u27 and ’Shengeh’ potentially had the highest browning index. AA could reduce peroxidase (POD) activity just in \u27Mari\u27, but NaHMP could beneficially suppress its activity in both cvs. \u27Manzanilla\u27 and \u27Mari\u27. In general, the monophenolase activity of polyphenol oxidase (PPO) was significantly higher than its diphenolase activity in all studied cultivars. The highest inhibitory effect on monophenolase activity was found in \u27Manzanilla\u27 fruit by CA and OA, while HR and NaHMP could suppress monophenolase activity of \u27Mari\u27 fruits. Diphenolase activity of PPO with pyrocatechol and dopamine HCl substrates was also dependent on olive cultivars. The minimum diphenolase activity of PPO for both substrates was found in \u27Zard\u27 fruit with the lowest browning index. The inhibitory effect of anti-browning agents on reducing diphenolase activity of PPO with dopamine hydrocholoride (DPOA) substrates was cultivar-dependend. Total phenolic content of treated fruits was higher than control. Overall, this result confirms that the potency of anti-browning agents on suppressing POD and PPOs enzymes that are involved in fruits browning was completely cultivar-dependend

Fruit Growth and Sensory Evaluation of ´Hayward´ Kiwifruit in Response to Preharvest Calcium Chloride Application and Orchard Location

In order to receive reliable results in the effect of preharvest calcium chloride (CaCl2) application on fruit growth and sensory characteristics of kiwifruit (Actinidia deliciosa cultivar ‘Hayward’) at the harvest time, a field experiment was carried out in two commercial orchards at different locations. The vines were sprayed with CaCl2 (1.5%), one, two, or three times in 35, 85 and 125 days after full bloom. The results showed that CaCl2 treatment significantly reduced fruit size, fresh weight and total dry matter content. Moreover, fruit growth relative attributes such as relative growth index, daily relative growth rate, daily transpiration rate, total carbon received by fruit and yield threshold pressure significantly decreased by thrice application. After thrice application of CaCl2, fruits showed better sensory quality. Overall, one time preharvest CaCl2 application had no-significant effect on the most fruits characteristics, while thrice application of CaCl2 could delay fruit ripening process