Pomology
Akram Fatemi; Asiyeh Safari; Mohsen Saeidi; Zahra Kolahchi
Abstract
Introduction
Drought is the most important limiting factor for the yield and quality of products in the world. Fertilizer application can mitigate drought stress in plants. Most farmers prefer to use inorganic (chemical) fertilizers because of their fast impact on plant growth. The reasonable ...
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Introduction
Drought is the most important limiting factor for the yield and quality of products in the world. Fertilizer application can mitigate drought stress in plants. Most farmers prefer to use inorganic (chemical) fertilizers because of their fast impact on plant growth. The reasonable cost of inorganic fertilizers and their availability are the other reasons. However, the long-term effects of organic fertilizers on plant growth and soil fertility has been proved. The grapevines are one of the most important garden products in the world as well as in Iran. It has been reported that the application of biochar has significant effects on soil fertility as well as plant growth. Biochars have properties such as highly porous structure, high specific surface area, higher water holding capacity of the soil, the long-term stability in the soil. In addition, our previous study indicated that it could decrease the hazard of sodium in soil compared with compost. In Iran, the cultivation area of grapevines was the second grade after the pistachio cultivation area in 2019. According to statistical data on agriculture in 2019, the cultivation area of irrigated and rain-fed grapevines in Kermanshah province was 7710 and 1515 ha, respectively. According to this report, the production of irrigated and rain-fed grapevines in Kermanshah province in 2019 was 82718 and 1763 tons, respectively. The effect of application of some inorganic and organic fertilizers under drought stress on yield, water use efficiency, and some biochemical characteristics of the grapevine leaves cultivar Bidane-Ghermez has been previously studied. In this research, the effect of drought stress and the application of potassium sulfate, compost, and biochar on antioxidant activities of the grapevine leaves cultivar Bidane-Ghermez was investigated.
Materials and Methods
A greenhouse study with a factorial experiment based on a block of randomized completely design was conducted with fertilizer treatments including control, potassium sulfate (1250 mg kg-1), compost (5% w/w), and biochar (10% w/w) without and with drought stress conditions (80 and 40% FC, respectively) during 2017-2018. For this research, the biochar was produced from apple tree pruning under low oxygen conditions by slow pyrolysis at 400 ◦C. The compost was purchased from the municipal compost factory of Kermanshah province. To evaluate drought stress and inorganic and organic fertilizers' application on antioxidant enzymes activities, the superoxide dismutase and peroxidase activities and total soluble protein of grapevine leaves were determined. The data were analyzed by ANOVA and the mean of studied characteristics was compared by Duncan’s test at 5% probability level using SAS software.
Results and Discussion
the results indicated that the interaction effect of fertilizers treatments and drought stress on the superoxide dismutase and peroxidase activities as well as total soluble protein was significant (P<0.01). Under drought stress conditions, among fertilizers’ treatments, the activity of superoxide dismutase for potassium sulfate was significantly lower than compost and biochar treatments (P<0.01). The results also showed that the peroxidase activity for compost was significantly higher than potassium sulfate and biochar treatments (P<0.01). Besides, the highest total soluble protein amount was found for biochar treatment (P<0.01).
Conclusion
according to the results of this study, it can be concluded that the increase of total soluble protein of grapevine leaves under drought stress conditions by biochar application contributed to the increase of superoxide dismutase and peroxidase activities also increasing the bioavailability of macro-and micronutrients. Biochar application increased significantly the potassium concentration of the leaves of the grapevines. Potassium regulates water movement at the plant and also provides a higher relative water content of grapevine leaves. Moreover, potassium decreases the non-stomatal effects are also attributed to stomatal closure during drought stress conditions. Furthermore, potassium contributes to protein synthesis. Biochar application also increased the phosphorus, copper, and magnesium of the leaves of the grapevine. Higher concentration of phosphorus under drought stress conditions caused the grapevine leaves to suffer less from phosphorus deficiency. Copper exists in superoxide dismutase and is considered a key player in superoxide detoxification. Under drought stress conditions, higher manganese concentration by biochar application resulted in more protection of the cellular membrane against Reactive Oxygen Species (ROS). For fertilizer recommendation in order to reduce drought stress effects on some antioxidant enzymes activities of Bidane-Ghermez grapevine leaves, the application of biochar is recommended first then potassium sulfate and compost.
Pomology
Asiyeh Safari; Akram Fatemi; Mohsen Saeedi; Zahra Kolahchi
Abstract
Introduction: the lack of water resources in arid and semi-arid regions is one of the most important limiting factors of the growth of plants, especially fruit trees. Grapevines are one of the most important horticultural products in the world as well as in Iran. The water content of plant tissues, their ...
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Introduction: the lack of water resources in arid and semi-arid regions is one of the most important limiting factors of the growth of plants, especially fruit trees. Grapevines are one of the most important horticultural products in the world as well as in Iran. The water content of plant tissues, their growth, and the availability of different nutrients in the soil are significantly reduced under water stress conditions. Therefore, the successful production of the plant under water stress conditions depends on the management of plant nutrition. By application of organic and chemical fertilizers, the physical, chemical, and biological properties of soil can be improved. Besides, it can reduce the adverse effects of drought stress conditions.
Materials and Methods: To evaluate the effect of compost, biochar, and potassium sulfate application on dry matter, relative water content (RWC), chlorophyll a, b, total, and carotenoid contents, as well as the concentration of macro-and micronutrients of leaves of grapevines ‘Bidane-Ghermez’ under two drought stress conditions, this experiment, was conducted in the research greenhouse during 2017-2018. The experiment was carried out as a factorial experiment based on a randomized complete block design (RCBD) with two factors and four replications. The first factor, without drought stress conditions (80% field capacity (FC)), and drought stress conditions (40% FC), and fertilizer treatments included potassium sulfate (1.25 g.kg-1), compost (5 % w/w), and biochar (10% w/w).
Results and Discussion: The results of the analysis of variance (ANOVA) showed that the interaction effect of drought stress ×fertilizers application was not significant for dry matter, and RWC (P>0.05). Also, the results of ANOVA indicated that the simple effect of drought stress conditions was not significant for dry matter but the simple effect of fertilizer application was significant for leaf dry matter (P<0.01). Without drought stress conditions, there were no significant differences in leaf dry matter between different fertilizer treatments. However, under drought stress conditions, the highest dry matter of grapevine leaves was observed in biochar, compost, and potassium sulfate, respectively. Also, there were no significant differences in leaf dry matter of grapevine between biochar treatment under drought stress conditions and all fertilizer treatments without drought stress conditions. The simple effect of drought stress conditions was significant for leaf dry matter (P<0.05). The results of ANOVA revealed that the interaction effect of drought stress ×fertilizer application was not significant for chlorophyll a, b, total, and carotenoid contents of grapevine leaves. However, the simple effects of drought stress conditions and fertilizer application were significant for chlorophyll a, b, total, and carotenoid contents of grapevine leaves (P<0.01). Relative water, chlorophyll a and carotenoid contents of grapevine leaves were not significantly different among fertilizers treatments. The increase of chlorophyll a/b ratio compared with control was changed in order biochar>potassium sulfate>compost. Moreover, the interaction effect of drought stress ×fertilizer application was significant for nitrogen (N), magnesium (Mg), ferrous (Fe), zinc (Zn), and copper (Cu) concentrations of grapevine leaves (P<0.01). The ANOVA indicated that the simple effects of drought stress conditions and fertilizer application had a significant effect (P<0.01) on macro- and micro-elements concentrations of grapevine leaves. By application of biochar, the concentration of P, K, Mg, and Cu of grapevine leaves significantly were higher than compost and potassium sulfate applications. This consequently resulted in higher chlorophyll a/b ratio and dry matter of grapevine leaves in biochar treatment for control under drought stress conditions.
Conclusion: Based on the results of this research, it can be concluded that the application of fertilizers reduced drought stress effects on biochemical characteristics and dry matter of grapevine leaves. According to the results, at first the application of biochar is recommended, then potassium sulfate and compost. Our previous results indicated that by application of compost, the available sodium (Na) of soil was increased 8.53 and 60.52 % for potassium sulfate and compost treatments compared to control, respectively. While, by application of biochar, the available Na of soil reduced 3.73 % in comparison with control. This finding is so important regarding the Na effects on soil structure, the toxicity of Na for plants as well as the interaction between Na and K. Considering K is a critical element to regulate the water content of plant tissue and reduces the hazards of water stress conditions, the higher concentration of Na prevents K uptake from the soil solution by plant.
Hosein Shekofteh; Mohammad Nick-Pour
Abstract
Introduction: Date bunch fading disorder has been one of the most important problems, which caused economic damage to date plantation area of Iran. It has been first reported on Mozafti cultivar in Kahnuj area, Kerman province. It has often been observed on soft and mid ripening cultivars such as Mozafti, ...
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Introduction: Date bunch fading disorder has been one of the most important problems, which caused economic damage to date plantation area of Iran. It has been first reported on Mozafti cultivar in Kahnuj area, Kerman province. It has often been observed on soft and mid ripening cultivars such as Mozafti, Mordaseng and Kalote. Furthermore, it usually appears on Mozafti cultivar when fruits change from Khalal to Rutab stage. The most important symptoms of this disorder are sudden wilting of fruits and necrotic strips on the upper surface of the main bunch stalk. Incidence and development of these symptoms increase by high temperature, low relative humidity, and hot and dry wind. Several research studies have been carried out on this disorder so far, but the only research about the effect of nutrition on disorder was performed by Rosta (2003). The aim of the present study was to investigate the effect of calcium and potassium spray on date bunch fading and some traits of date fruit in Rigan region, Kerman province.
Materials and Methods: The experiment was conducted based on randomized complete block designs with three replicates in Rigan located in east south of Kerman province, Iran, in 2012. Treatments were: T1: control, T2: spray of calcium nitrate at the concentration of 5 ppm, T3: spray of potassium sulfate at the concentration of 5 ppm, and T4: combined spray of calcium nitrate and potassium sulfate at the concentration of 5 ppm. Treatments were applied at Kimri, Hobabok and Khalal stages. Sampling was performed from 3 date palms (3 bunches from each date palm were selected randomly) at the second date harvest. Totally, the traits of 200 fruits were measured in each date palm. The traits measured in the present study were: fruit length, fruit diameter, fruit weight, stone weight, stone diameter, and bunch fading percentage.
Results and Discussions: According to the data of variance analysis, treatments had a significant effect on wet fruit weight, fruit length, fruit diameter, stone weight, stone diameter, and bunch fading percentage at 1℅ level. The highest wet fruit weight, fruit length, fruit diameter, stone weight, and stone diameter were attained in the treatment containing combined application of calcium nitrate and potassium sulfate. Furthermore, the lowest amounts of these traits were obtained in control. The lowest and highest percentage of date bunch fading belonged to the combined treatment of calcium nitrate and potassium sulfate, and control, respectively. In general, application of calcium nitrate and potassium sulfate with each other improved fruit traits and reduced bunch fading percentage. Calcium mobility in the plant takes place mainly in the xylem, together with water. Therefore, calcium uptake is directly related to plant transpiration rate. Conditions of high humidity, cold and low transpiration rates may result in calcium deficiency. Salinity might also cause calcium deficiency because it decreases water uptake by the plant. Since calcium mobility in plants is limited, calcium deficiency appears in younger leaves and in fruits, because they have a very low transpiration rate. Therefore, it is necessary to have a constant supply of calcium for continued growth. Calcium deficiency is usually caused by low calcium availability or water stress which results in low transpiration rates. Calcium is an essential plant nutrient with many roles including participation in metabolic processes of other nutrients uptake, promotion of proper plant cell elongation, and improvement of cell wall structure – calcium is an essential part of plant cell wall. It forms calcium pectate compounds which give stability to cell walls and bind cells together. It also helps protecting the plant against heat stress - calcium improves stomata function and participates in induction of heat shock proteins. In addition, it helps protecting the plant against diseases - numerous fungi and bacteria secret enzymes which impair plant cell wall. Stronger cell walls, induced by calcium, can avoid the invasion of diseases. Considering the important roles of calcium, calcium spray increased thetraits of date fruit and decreased bunch fading percentage. As an important element in photosynthesis, , potassium regulates the opening and closing of stomata, and therefore regulates CO2 uptake. Potassium plays a major role in the regulation of water in plants (osmo-regulation). Both uptake of water through plant roots and its loss through the stomata are affected by potassium. Moreover, protein and starch synthesis in plants requires potassium, so that the enzymes responsible for starch synthesis are activated by potassium. Potassium has also an important role in the activation of many growth related enzymes in plants. Results of the analysis of the studied soil showed that available potassium content in soil was less than plant requirement. So spraying of potassium sulfate could result in the improvement of date fruit traits and reduction of bunch fading disorder. Finally, combined spray of calcium and potassium caused a significant reduction in date bunch fading percentage.
Conclusion: The results of the present study indicated that spray of calcium and potassium solely improved fruit traits and bunch fading disorder, but maximum values of fruit yield components and minimum bunch fading percentage obtained from foliar spray of calcium and potassium together.
