نوع مقاله : مقالات پژوهشی
1 استادیار بخش علوم باغبانی دانشکده کشاورزی دانشگاه شهید باهنر کرمان
2 دانش آموخته کارشناسی ارشد علوم و مهندسی باغبانی دانشگاه شهید باهنر کرمان، کرمان، ایران.
عنوان مقاله [English]
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 aim of this research was to investigate the effect of different concentrations of γ-aminobutyric and salicylic acid compounds on the physiological characteristics, photosynthetic components and quality characteristics of the seedlings of Lycopersicum esculentum cv. Seyran and to introduce the best concentration of these hormonal and pseudo hormonal compounds in the 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 characteristics 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). Based on the results of analysis of variance, the simple effect of GABA and the simple effect of salicylic acid on leaf stomatal conductance and net photosynthesis rate were significant at the level of one percent and their interaction was significant at the level of five percent. The results showed that the simple and mutual effects of GABA and salicylic acid on the level of catalase enzyme activity are significant at the five percent level. Also, the simple effect of GABA at the level of one percent and the simple effect of salicylic acid, as well as the mutual effect of these two on the trait of malondialdehyde at the level of five percent, are significant (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).
Conclusions In sum, it can be concluded that the use of γ-aminobutyric acid as a biological compound and salicylic acid as a growth regulator had a positive effect on most of the traits studied in Lycopersicum esculentum cv. Seyran seedlings and increased the diameter of seedlings, relative water content, total chlorophyll, yield, activity of catalase and peroxidase enzymes, proline and reduction of ion leakage and malondialdehyde. It seems that the highest applied concentration of GABA in this study (10 mg/l) and the highest concentration of salicylic acid (1.5 mM) brought the best results and improved the production of seedling while maintaining its quality.
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