Growing vegetables
Najme Zeinali Pour; Fatemeh Aghebati; Bahareh Nejhad Shahrokh Abadi
Abstract
Introduction
Recently, the market demand for high quality tomato fruit is increasing. This product is one of the most important vegetables produced all over the world, and in the last few decades, there has always been a growing trend for its production and consumption. Today, seedling production is ...
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Introduction
Recently, the market demand for high quality tomato fruit is increasing. This product is one of the most important vegetables produced all over the world, and in the last few decades, there has always been a growing trend for its production and consumption. Today, seedling production is considered as a specialized and profitable industry all over the world, which also has a good development speed in our country. The production of healthy and strong seedlings is a prerequisite for proper plant growth and economic production, and nutrition plays an important role in this. Today, the use of natural and organic compounds in various sectors of production and agriculture is increasing. One of these organic compounds, is γ-aminobutyric acid. Biofertilizers are used in order to reduce the consumption of chemical fertilizers and thus reduce the negative environmental effects and increase the yield of plants in agricultural systems. Salicylic acid is a natural phenolic compound and one of the endogenous plant regulators that exists in most plants and is an important component in the signaling pathway. Salicylic acid is effective in regulating the process of plant growth and development, germination, flowering, opening and closing of stomata, respiration, absorption and transfer of ions, photosynthesis, maintaining membrane integrity and plant growth rate. The objective of this study was to examine the influence of varying concentrations of γ-aminobutyric acid and salicylic acid compounds on the physiological attributes, photosynthetic components, and quality traits of Lycopersicum esculentum cv. Seyran seedlings. The aim was to identify the most effective concentration of these hormonal and pseudo-hormonal compounds under the specific conditions of this research.
Materials and Methods
This experiment was conducted in 2017 in the research greenhouse of Shahid Bahonar University of Kerman as a factorial in a completely randomized design with three replications. Lycopersicum esculentum cv. Seyran seeds were planted and after the seedlings reached the stage of three to four leaves and were well established, the first foliar spraying was done with complete NPK fertilizer containing other micronutrients. After 75 % of the seedlings reached the five leaf stage, foliar spraying of the treatments with γ-aminobutyric acid with concentrations of 0, 5 and 10 mg/l and half an hour later with salicylic acid with concentrations of 0, 0.5 and 1.5 mM was performed. After 15 days, the second foliar spraying steps of the treatments were repeated. Traits studied include; seedling stem diameter, ion leakage, relative water content, total chlorophyll, yield, stomatal conductance, net photosynthesis rate, catalase, peroxidase, proline and malondialdehyde.
Results and Discussion
Based on the results of analysis of variance, the simple effect of GABA and the simple effect of salicylic acid on seedling diameter, ion leakage and total chlorophyll were significant at the level of one percent and their interaction was significant at the level of five percent. In the of relative water content and yield, the simple effects of GABA and salicylic acid, as well as the interaction of the two, were significant at the 1% level (Table 1). Results showed that the largest plant diameter and relative water content in GABA 10 mg/l and with the combined use of 1.5 mM salicylic acid and the lowest plant diameter and relative water content in the condition of not using GABA and using salicylic acid in the amount 0.5 mM was obtained. Also, the highest amount of ion leakage occurred in the control plants and the lowest amount of ion leakage is related to the treatment of 10 mg/l GABA combined with 1.5 mM salicylic acid. Investigations showed that a increase in performance compared to the control occurs when using the combination of GABA 10 mg/l along with 0.5 and 1.5 mM salicylic acid (Table 3). According to the analysis of variance results, both the individual effects of γ-aminobutyric acid (GABA) and salicylic acid on leaf stomatal conductance and net photosynthesis rate were found to be significant at the one percent level, with their interaction being significant at the five percent level. Furthermore, the analysis revealed that the individual and combined effects of GABA and salicylic acid on catalase enzyme activity were significant at the five percent level. Additionally, the individual effect of GABA at the one percent level, the individual effect of salicylic acid, and their combined effect on malondialdehyde levels were all significant at the five percent level (refer to Table 2). According to the average comparison results, the highest level of leaf stomatal conductance was observed in the concentration of 1.5 mM salicylic acid in all three application levels of GABA, and the interaction treatment of 10 mg/l GABA with 1.5 mM salicylic acid had the highest net photosynthesis rate and activity of catalase and peroxidase enzymes. The highest amount of proline accumulation occurred in the treatment combination of GABA 10 mg/l along with each of the three concentrations of salicylic acid. The highest accumulation of malondialdehyde was observed in the control sample (without the use of γ-aminobutyric acid and salicylic acid) and the lowest amount of this characteristic was obtained in the combined treatment of GABA 10 mg/l with 0.5 mM salicylic acid (Table 4).
Conclusion
In summary, the utilization of γ-aminobutyric acid as a biological compound and salicylic acid as a growth regulator exhibited a beneficial impact on most of the studied traits in Lycopersicum esculentum cv. Seyran seedlings. This included enhancements in seedling diameter, relative water content, total chlorophyll levels, yield, catalase and peroxidase enzyme activity, proline content, as well as reductions in ion leakage and malondialdehyde levels. It appears that the highest applied concentration of GABA (10 mg/l) and the highest concentration of salicylic acid (1.5 mM) yielded the most favorable results, effectively improving seedling production while preserving its quality.
Growing vegetables
Najme Zeinali Pour; Fatemeh Aghebati
Abstract
Introduction
Drought stress is one of the most common environmental stresses that limits agricultural production through disruption of physiological processes and reduces plant performance. Since in most parts of the world, including in Iran, melon plants and generally pumpkins are cultivated in hot ...
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Introduction
Drought stress is one of the most common environmental stresses that limits agricultural production through disruption of physiological processes and reduces plant performance. Since in most parts of the world, including in Iran, melon plants and generally pumpkins are cultivated in hot and dry areas, and in these areas the main challenge is due to the limitation of suitable water for agriculture, the possibility of various types of stress, including water deficit stress (partial or severe) in the cultivation of these plants is relatively high. From this point of view, it seems necessary to study and know the tolerant cultivars and masses and ways to improve water management. Among the physiological characteristics, leaf water status, membrane stability, photosynthesis changes and related factors are of special importance in relation to tolerance of stressful conditions and especially dehydration. A review of scientific sources shows that due to the relative importance of melons among fruit vegetables, no comprehensive research has been done on the effect of water stress on the yield and stress level evaluation indicators in Garmak and Dudaim groups. This research has tried to investigate and evaluate this issue in some products of this group of vegetables that have been less studied.
Materials and Methods
This experiment was carried out in the form of a split plot design in the form of randomized complete blocks and in four replications in the Mahan greenhouse complex located 25 km from Kerman province. Experimental treatments include; There were three plants (Shahdad and Isfahan cantaloupe (Garmak) and Birjand dudaim (Cucumis melo group dudaim)) and three levels of irrigation in order to apply stress (starting irrigation at matric potentials of -45 (control), -55 and -65 kPa). The parameters of net photosynthesis rate, stomatal conductance, leaf transpiration rate, leaf chlorophyll index, water potential, osmosis and turgor potential of leaves, water use efficiency and leaf relative humidity were measured and evaluated.
Results and Discussion
Based on the results of the first and third tables, the three population were different in the changes in the net rate of photosynthesis under different levels of dehydration stress, but the change process in them was largely similar. The highest rate of net photosynthesis and leaf stomatal conductance was obtained in Isfahan cantaloupe population plants under control irrigation (-45 kPa), which, of course, did not have a significant difference with plants under -55 kPa dehydration stress, and the lowest rate of these traits in Birjand dudaim under irrigation at matric potential -65 kPa was measured. A more severe level of dehydration stress (starting irrigation at matric potential of -65 kPa) reduced the net photosynthetic rate in all three plants compared to control irrigation (-45 kPa). It seems that under the conditions of this experiment, the reduction of the relative humidity of the leaves occurs following the reduction of the water potential in the leaves and leads to the closing of the stomata in order to increase the resistance of the mesophyll cells against the dehydration stress and parallel to these changes, the reduction it happens in the amount of stomatal conductance and as a result the rate of net photosynthesis. The rate of leaf transpiration in matric potentials of -55 and -65 kPa has decreased significantly compared to control irrigation. The decrease in transpiration rate in plants under stress is probably due to stomatal closure and reduction of stomatal conductance. Plants under stress prevent excessive water loss through transpiration by regulating stomata. Based on the results of the second and fourth tables, by measuring the water potential, osmosis and turgor potential of the leaves of the three population used, it was shown that the water potential of the leaf decreased with the increase in the water stress levels. The slope of this decrease is such that the potential values are equal to the osmotic potential values of the leaf and the turgor potential, which is the result of the difference between the osmotic and water potentials of the leaf, also decreases, but it is the turgor pressure that has increased and in a more positive way. even at the end of the stress period and at the most extreme level of stress, it reaches zero. This same turgor pressure maintains the normal state of the membrane in cells under dehydration stress. In fact, the extreme level of water stress in this experiment significantly reduced the osmotic potential of the leaf. The highest amount of osmotic potential (8.5 Bar) for these plants was obtained in the usual or control irrigation treatment and the lowest (22 Bar) in the more severe level of dehydration stress treatment (watering as soon as the matric potential reaches -65 kPa) was obtained. At matric potentials of -45 and -55, there was no significant difference between the three population in terms of leaf relative humidity percentage, but in Garmak and Dudaim populations, the relative humidity of leaves was significantly reduced by applying stress at the matric potential of -65 kPa. This is despite the fact that in the Isfahan cantaloupe, the decrease in the relative humidity of the leaf was not significant. The existence of this difference in the reduction of the relative humidity of the leaves in the conditions of stress between the three plants may be due to the genetic differences in the ability of the stomata of the plants to lose water. In fact, more drought tolerant population (Isfahan Garmak) compared to Shahdad Garmak and Birjand dudaim have better maintained relative humidity until the end of the stress.
Conclusion
Plants with the ability to regulate osmosis can be considered as drought tolerant plants. This adjustment in the plants of this experiment occurred in the condition that in all three population, the osmotic potential decreased by -19 to -22 Bar. This event is to some extent guaranteeing the performance of pure photosynthesis, although at a low rate in these plants, in the condition that the water potential of the cell has become negative at the level of severe water deficit stress, at the end of growth.
Growing vegetables
Najme Zeinali Pour; Fatemeh Aghebati
Abstract
Introduction
Portulaca oleraceae is used in many countries for a variety of purposes, including human nutrition and the conversion and pharmaceutical industries. The edible parts of Portulaca oleracea are the young organs, especially the brittle leaves and stems. Over time, this medicinal herb ...
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Introduction
Portulaca oleraceae is used in many countries for a variety of purposes, including human nutrition and the conversion and pharmaceutical industries. The edible parts of Portulaca oleracea are the young organs, especially the brittle leaves and stems. Over time, this medicinal herb has been forgotten. Drought, on the other hand, is a factor in the decline of crops and horticulture around the world. Given the vastness of arid and semi-arid regions in Iran and also the reduction of access to water resources, appropriate arrangements should be made for the optimal use of water in the agricultural sector. Changing the planting pattern and using useful and resistant alternative species such as drought-tolerant medicinal plants can enable the optimal use of limited water resources. GABA is an important non-protein amino acid that plays a positive role in increasing plant resistance to stress.
Materials and Methods
This experiment was carried out in 2020 as a factorial based on a completely randomized design with three replications in the vegetable research greenhouse of the Faculty of Agriculture, Shahid Bahonar University of Kerman. Experimental treatments included different levels of GABA (0, 20, and 40 mM). Treatment with different concentrations of GABA was done in two stages of 6 and 12 leaves of portulaca oleracea and foliar application and application of dehydration stress in three levels of control, medium and severe at irrigation intervals of 7, 14, and 21 days from 6 leaf stage of plants to the end.
Results and Discussion
According to the analysis of variance, the effect of GABA at different concentrations and dehydration stress on plant height was significant at the level of 5% probability. Based on the mean comparison test, the highest plant height was obtained in GABA treatment of 40 mM and irrigation intervals of 7 days (control), and the lowest of this trait was obtained in GABA zero treatment and irrigation intervals of 21 days (highest stress level). The results of analysis of variance showed that the effect of GABA at different concentrations and dehydration stress on vegetative yield was significant, the interaction between irrigation intervals and GABA was significant at 5% level. Based on the mean comparison test, the highest vegetative yield was obtained in GABA treatment of 40 mM and irrigation intervals of 7 days and the lowest in control treatment and irrigation intervals of 21 days. According to the results of the analysis of variance table, the effect of GABA at different concentrations and dehydration stress on the amount of malondialdehyde was significant at the level of 1% probability. Based on the means comparison test, the highest amount of this trait was obtained in the control treatment. Comparison of the mean of the data showed that the effect of GABA at different concentrations and dehydration stress caused a significant difference in the probability level of 1% in the proline content of the data. Based on the mean comparison test, the highest amount of proline was observed in GABA treatment of 40 mM and irrigation intervals of 21 days and the lowest amount was observed in control treatment and irrigation intervals of 7 days. As can be seen in the comparison table of means, the highest activity of superoxide dismutase enzyme was obtained in GABA treatment at 40 mM and irrigation intervals of 14 days and the lowest in control treatment and irrigation intervals was 7 days (Table 2). The results of this study showed that the effect of GABA at different concentrations and dehydration stress on the activity of catalase was significant at the level of 1% probability. As can be seen in the comparison table of means, the highest level of catalase activity was 40 mM in GABA treatment and 21 days irrigation intervals and the lowest in GABA treatment was 40 mM and irrigation intervals were 7 days.
Conclusion
The results of this study indicate that GABA is able to greatly alleviate the oxidative stress caused by dehydration in Portulaca oleracea. This effect is quite evident in oxidative parameters, especially the activity of antioxidant enzymes. The concentration of 40 mM GABA was the most effective treatment in mitigating the effects of irrigation. The results show that the use of GABA makes Portulaca oleracea tolerant to dehydration stress.
