Pomology
M. Nezami; M.R. Fatahi Moghadam; A. Ebadi; Z. Zamani
Abstract
IntroductionStrawberry is known as one of the most important temperate small fruits which is cultivated in the field, greenhouse and high tunnels in the most regions of the world. The role of gibberellin and auxin in increasing fruit size of strawberries have been reported. One of the major problems ...
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IntroductionStrawberry is known as one of the most important temperate small fruits which is cultivated in the field, greenhouse and high tunnels in the most regions of the world. The role of gibberellin and auxin in increasing fruit size of strawberries have been reported. One of the major problems of strawberry production in greenhouse is the fruits malformation which has reduced the market value of the fruit. Gibberellin and auxin have been different effects in vegetative and reproductive of growth stages. The purpose of this research was to improve the vegetative and reproductive indices of the fruit and to control the malformation problem by stimulating the development of seeds on the fruit and stimulating the growth of the fruit receptacle by gibberellin GA3. Materials and MethodsExperiments were conducted in a commercial greenhouse in Karaj, Hashtgerd New City, Phase 7 during 2017-2019. Two separate experiments (spraying hormones on whole plant or immersing individual fruitlets on hormone solution) were designed and implemented in a commercial greenhouse unit. In the first experiment: GA3 was at concentrations of 50, 100 and 150 ppm and IBA at concentrations of 20, 40 and 60 ppm in growth stages of 60 and 65 according to BBCH worldwide model. In the second experiment, fruits were immersed in NAA with concentrations of 20, 40 and 60 ppm and GA3 with concentrations of 25, 50 and 100 ppm at fruit growth stages 70 and 73 according to BBCH procedure. After reaching the red stage, the fruits were manually harvested and transferred to the laboratories for additional tests. Vegetative and reproductive traits were evaluated including leaf area, number of leaves, crown circumference, plant height, number of flowers and fruit dimensions. Fruit biochemical characteristics include: total soluble solids, titratable acid content of fruit, anthocyanin and antioxidant capacity, total phenolics, catalase and superoxide dismutase enzymes activities and content of vitamin C were evaluated. The experiments were designed and implemented in the frame of a randomized complete block design. The data were analyzed by SAS ver.9.4 and SPSS ver. 22 software, the mean data were compared based on Duncan's multi-range test, and the graphs were drawn by Excel 2013 software. Results and DiscussionFoliar spraying with gibberellin had a significant effect on several characteristics, including leaf area, crown circumference, number of flowers, and plant height at the 1% level of significance. However, it did not yield a significant impact on the attribute of leaf number. The increase in vegetative growth could be due to the synthesis of more amino acids in the stimulation of gibberellin treatment. Gibberellin treatments increased the vegetative growth of the plant and increased the number of flowers, but their growth was stopped after fruit formation and no fruits were formed in gibberellin spraying. This can be due to the existence of an antagonistic relationship between vegetative parts and fruit developments. Auxin hormone treatments had a significant effect on increasing fruit size and reducing the percentage of malformed fruits. GA3 at concentration of 50 ppm improved plant vegetative characteristics such as: plant leaf area, plant crown circumference, plant height and number of flowers, while IBA reduced fruit deformity by 40% and also increased the amount of total soluble solids, the titratable acid content of the fruit and the antioxidant content of the fruit. In general, gibberellin at a concentration of 50 ppm in order to increase plant vegetative indices and auxin at a concentration of 60 ppm were statistically effective. In second experiment, it seems that three levels of gibberellin treatment have increased all traits related to fruit compared to auxin and control. GA3 at a concentration of 100 ppm, causing an increase in fruit size, fruit weight and the biochemical properties of the fruit and the deformity decreased by 37/5% while NAA at a concentration of 60 ppm increased the amount of fruit anthocyanin as well as total fruit phenolics and vitamin C content. ConclusionIn the first experiment, gibberellin foliar application at a concentration of 50 ppm had the greatest effect on vegetative growth indicators. Also, in the same experiment, it was found that the use of GA3 in high concentrations has the negative effects on flowering and fruit growth., while it increases the amount of runner production. Also, IBA at a concentration of 60 ppm was the most effective treatment in fruit indices. In the second experiment, gibberellin at a concentration of 100 ppm was the most effective treatment in fruit and its biochemical traits, while NAA auxin in the second experiment showed a lower response to fruit than IBA auxin in the first experiment.
Ali Tajabadipour; mohammadreza fattahi; zabihollah zamani; Fatemeh Nasibi; Hossein Hokmabadi
Abstract
Introduction: Spring cold injury is one of the main limiting factors to production and distribution of pistachio. Pistachio is one of the most valuable and exported agricultural crops of Iran. Since, spring frosts results to considerabe damage to this plant, hence, it is important to investigate methods ...
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Introduction: Spring cold injury is one of the main limiting factors to production and distribution of pistachio. Pistachio is one of the most valuable and exported agricultural crops of Iran. Since, spring frosts results to considerabe damage to this plant, hence, it is important to investigate methods for reducing freezing damage. For this reason, selection of rootstocks and cultivars are an important objective in breeding programs. Freezing temperatures (below 0ºC) cause the movement of water from the protoplast to the extracellular space, resulting in the growth of extracellular ice crystals and ultimately, cell dehydration. Plants have developed complex processes to survive and recover from unfavorable conditions. To tolerate cold stresses, plants develop multiple mechanisms, including the accumulation of cryoprotective molecules and proteins, alterations in membrane lipid composition, and primary and secondary metabolite composition, as well as changes in global gene and protein expression Frost affects cell membranes, which become less permeable, and even break, giving rise to the leakage of solute from damaged cells. There is often a good correlation between ion leakage and freezing tolerance (22). Sugars may depress the freezing point of the tissue and act as a nutrient and energy reserve, alter phase properties of membranes in the dry state and act as cryoprotectants to preserve protein structure and function. Other compounds acting similarly are lipids, soluble proteins and free proline (44). Proline seems to have diverse roles under osmotic stress conditions, such as stabilization of proteins, membranes and subcellular structures and protecting cellular functions by scavenging reactive oxygen species (23). The aim of the present study was to evaluate different degrees of sensitivity to low temperatures in different genotypes and ‘Ahmad-Aghaii’ cultivar in relation to physiological and biochemical changes in field conditions.
Materials and Methods: In order to determine the effects of rootstock on pistachio cultivar ‘Ahmad-Aghaii’ under freezing stress conditions, an experiment was carried out as factorial based on a randomized completely design (RCD) with four replications. Treatments consisted of two levels: 1- rootstock genotype (four cold sensitive and tolerant rootstocks) and 2- temperatures (-2 and -4 ºC). The sampling was performed in full bloom stage from apical branches of pistachio cultivar ‘Ahmad-Aghaii’ budded on these rootstock genotypes. The branches in pots contain distillted water treated under -2 and -4 °C for 2 h. After treatment, the chilling index was determined. Flower clusters were used for measuring physiological and biochemical parameters. All determinations were carried out in four triplicates and data were subjected to analysis of variance. Analysis of variance was performed using the ANOVA procedure. Statistical analyses were performed according to the SAS software. Significant differences between means were determined by Duncan’s multiple range tests. P values less than 0.05 were considered statistically significant.
Results and Discussion: The results showed that chilling index was significantly lower in the cold-tolerant rootstocks than cold-sensitive rootstocks at -2 and -4 ºC. Also, Results indicated that electrolyte leakage, hydrogen peroxide (H2O2) and malondialdehyde (MDA) were significantly lower in tolerant rootstocks than sensitive ones. The content of soluble carbohydrate, total protein and proline were significantly higher intolerant rootstocks than sensitive ones. The activity of anti-oxidant enzymes ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase (CAT) in tolerant rootstocks was greater than sensitive rootstocks. The reaction of temperature and rootstock indicated that electronic leakage, proline, H2O2,و and MDA significantly increased in -4 ºC. The activity of anti-oxidant enzymes APX, GPX and CAT decreased in -4 ºC as compared to -2 °C especially in cold-sensitive rootstocks. Some researchers believe that the accumulation of proline is as an index to select the drought-resistance varieties (26, 48). Stated that there was no comprehensive information about the relationship between the accumulation of proline and tension resistance. Research on apricot and peach confirmed the results of the present study because this pattern is also seen in their proline level (26 and 41). While the starch concentration decreases during the dormancy, the amount of proline increases which is in accordance with their results (36).
Conclusions: In this study, the damage of the membrane increased with decreasing temperature. The results showed that the rootstocks could increase the resistance to cold by increasing the amount of soluble sugars, protein, proline and the activity of the antioxidant system in the shoots and leaves of the scion. Regarding physiological and biochemical studies, it was determined that ‘Ahmad-Aghaii’ cultivar budded on cold tolerant rootstocks had higher soluble sugars, total protein, proline and CAT, APX and GPX enzymes activity and had less chilling index, ion leakage, H2O2 and MDA, which indicates less damage to the membrane of the cell and its contents compared with the cultivar 'Ahmad-Aghaii' budding to sensitive rootstocks. Consequently, the findings of this study selected TR1 as the most tolerant rootstock compared to other ones.
yahya selahvarzi; zabihollah zamani; A.R. Talaie; mohammadreza fattahi
Abstract
Introduction: Pomegranate (Punica granatum L.) belonging to the family Punicaceae, native to subtropical regions of Iran and adapted to arid or semi arid climates with mild winters. Pomegranate is fairly drought tolerant but requires regular irrigation to produce high yield and fruit weight. Large ...
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Introduction: Pomegranate (Punica granatum L.) belonging to the family Punicaceae, native to subtropical regions of Iran and adapted to arid or semi arid climates with mild winters. Pomegranate is fairly drought tolerant but requires regular irrigation to produce high yield and fruit weight. Large parts of Iran within the boundaries of central deserts (Dasht-e-kavir and Kavir-e-Loot) have arid or semi-arid conditions which make them suitable for pomegranate production. However drought crisis and water resources restriction are very serious in these areas.
Materials and Methods: This experiment was conducted on 7-year old pomegranate cv. Shahvar trees from 2013 to 2014 in Torbat-e-Heydarieh, Razavi Khorasan, Iran. Irrigation treatments and Gibberellic acid application were used in Completely Randomized Split-Plot Design with four replications. Irrigation treatments included [1-control: 100% of estimated crop evapotranspiration (Etc) 2-Sustained deficit irrigation (SDI): watering was constantly used at 50%Etc, and 3-Regulated deficit irrigation (RDI): not watering was imposed until fruit set and then irrigation was applied same as control]. Foliar application of Gibberellic acid was done with two concentrations (0 and 150 ppm) at early May and September. Precipitation and pan evaporation (Ep) was recorded by weather station that located at 15 km distance from the studied orchard. Daily crop reference evapotranspiration (ETo) was estimated by penman-monteith equation. Trees were drip-irrigated by two lateral lines parallel to the tree row and four emitters that each one delivers 4 liters per hour. Fruit weight and numbers, tree production (yield), peel, arils and juice percent and finally fruit cracking of each treatment were determined at ordinary harvest time in late of October. Some uniform and intact fruits per treatment transferred to cold storage (T= 5 ◦C, RH= 85-90%). After storage period the fruits transfered to shelf life condition (7 days at 20 ◦C and RH= 65-70%) to evaluate physiochemical traits at 2 different storage periods (9 and 18 weeks). Weight loss and chilling index were determined during 3 weeks intervals of storage. Weight loss was evaluated by a gravimetric method and results were expressed as percent of initial fresh weight. Chilling index was quantified by 5 point scale of fruit husk injury: (1: without disorder, 2: slight disorder signs 3: moderate signs 4: severe signs and 5: unmarketable).
Results and Discussion: In present research the effects of deficit irrigation treatments on all the measured attributes was significant at harvest time (p≤ 0.01). But Gibberellic acid spray had significant effect only on Fruit weight, juice percent and fruit cracking disorder. Likewise, deficit irrigation and Gibberellic acid interaction showed significant difference for fruit weight and cracking disorder. The results indicated that fruit weight, total yield and fruit juice in regulated deficit irrigation increased by 39.6, 17.1 and 16.6 percent in compare with control, respectively. Fruit numbers in control trees (108.3) was more than sustained (93.6) and regulated (87) deficit irrigation. It is possible that sustained (SDI) and regulated (RDI) deficit irrigation have decreased sprouting growth and consequently second or third waves of pomegranate flowers that forming on these shoots was lower by water restricting. Pomegranate peel percent in studied deficit irrigation strategies were less than control and naturally aril percent was more in these treatments. In other hand, the highest fruit cracking (9.1%) and lowest fruit weight (205.8 g) occurred in sustained deficit irrigation. However Gibberellic acid application could increase fruit weight and alleviate cracking disorder. The results of cold storage experiment showed that maturity index, antioxidant activity, total anthocyanin and chilling index improved by Sustained deficit irrigation. Variations of ripening index during cold storage occurred because of sugar conversion, not the changes of organic acids content. Indeed, rate of starch degradation to simple carbohydrates in fruits increase under drought condition. Probability drought in deficit irrigation treatments as an oxidative stress motivates antioxidant system and consequently increases chilling resistance in pomegranate fruits. Preharvest Gibberellic acid application amended weight loss and increased total anthocyanin and antioxidant activity during cold storage.
Conclusions: On the base of this study it seems that using of some deficit irrigation strategies have acceptable consequences on pomegranate fruit production at conditions of water resources restriction. Likewise Gibberellic acid application on trees that were subjected by deficit irrigations ameliorates the adverse effects of drought stress.
