Growing vegetables
M. Zare Mehrjerdi; N. Safari; S. M. Kharrazi; A. Khadem; A. Sharifi
Abstract
Introduction In addition to providing the necessary energy for photosynthesis, light controls many plant metabolic processes. Nowadays, the use of supplemental light significantly improves the quality of the food product in the conditions of lack of natural light in the autumn and winter seasons. ...
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Introduction In addition to providing the necessary energy for photosynthesis, light controls many plant metabolic processes. Nowadays, the use of supplemental light significantly improves the quality of the food product in the conditions of lack of natural light in the autumn and winter seasons. Light-emitting diodes have been proposed as alternative light sources in controlled agricultural environments. These lamps are the first light sources with the ability to control the light spectrum. Therefore, by controlling the light spectrum and matching the wavelength of LED lamps with the photoreceptors of the plant, the performance and quality of the plant is improved. Cucumber is one of the most important greenhouse plants and its seedlings are generally produced during the autumn and winter seasons, when natural light is relatively low; therefore, the use of supplementary light is required. The use of artificial light sources in fully controlled conditions can change and improve the growth conditions of the plant and also improve its quantitative and qualitative traits. In this research, the aim was to investigate the effect of different qualities of light on the morphophysiological indicators of cucumber seedlings. Materials and Methods This research was performed at the Horticultural Plants Biotechnology Department, Industrial Biotechnology Research Institute of Khorasan Razavi. First, the seeds of the cucumber plant (Cucumis sativus L. var. Officer) were planted in a planting tray, and placed under the light panel with different light treatments. The experimental treatments included four light qualities including white light (6000-6500K) blue light (460-470 nm), red light (625 nm) and combined light (blue + red + white). The amount of photosynthetic photon flux was considered the same in all light treatments, which was equal to 2.75 µol m-2 s-1 CO2 assimilation. Thirty days after planting of seeds, the growth of plants were measured in three stages every 10 days. In each stage, 4 plant samples were selected and then plant height, leaf area, fresh and dry weight of shoots and roots, plant dry matter index and leaf chlorophyll content were measured. Data preparation was done in Excel software, data analysis was done using JMP-8 software and treatment averages were compared using LSD test at 5% probability level. Results and DiscussionThe results of the experiments showed that the quality of light was significantly effective on the growth indicators of Cucumber plants. Plant height in red light and blue light treatments compared to the white light and combined light (red+blue+white with the same intensity) treatments, increased by more than 130% and 60%, respectively. The lowest height was observed in plants grown under combined light, 9 and 14.25 cm after 40 and 50 days of cultivation respectively. The exposure of cucumber seedlings to the red and combined lights recorded the highest and the lowest leaf area in the plants, 618.65 and 377.26 cm2 respectively. Also white light significantly improved the dry weight of the roots. It is worth to mention that the highest plant fresh weight was observed in blue and white lights, 20.9 and 19.5 g respectively. For parameters such as dry weight, dry matter index, and pigment content, the light treatments did not exert a significant effect. However, the utilization of red and blue light, both individually and in combination, positively impacted plant growth. Notably, exposure to red light alone led to a significant increase in leaf surface area, root dry weight, and plant height compared to other light conditions. Previous studies have indicated that red light enhances leaf area, stem length, and fresh weight of plants. Leaves play a critical role in plant photosynthesis and overall growth. Therefore, increasing the leaf area in the plant increases the amount of photosynthesis, growth and development of the plant. In this study, with the increases of the leaf area in the plant and the subsequent increases in the amount of photosynthesis, allocation of dry mater to root increased. The results of the research has been shown that the combination of blue and red wavelengths in pepper, tomato and cucumber seedlings is effective in stimulating plant growth and improving the morphological characteristics under controlled conditions. Blue and red lights can increase the proton flow rate of epidermal cells through the separation mechanism and thus affect leaf development. Blue light directly through the interaction with proton pumps and indirectly through receptors, affects proton pumps by modulating passive ion conduction of potassium and calcium channels. Conclusion According to the results of this research, it was found that exposing the plant to different light quality had different responses in the cucumber plants. Although variables such as dry weight and the amount of photosynthetic pigments were not significantly affected by light quality, however, traits such as plant height, leaf area, root dry weight, and plant fresh weight were affected by light quality. The affected parameters are among the traits that are influenced by the gibberellin hormone and according to the reports related to the effect of light quality on the gibberellin biosynthesis and response to this hormone. It seems that plant action to the quality of light can be attributed to the regulation of this hormone. So it is possible to choose the appropriate light quality in fully controlled conditions according to the production goal and results. In this research, according to the plant leaf rea, root dry weight and plant height, it was determined that white light can be used in the seedling production stage.
Mehdi Aran; Bahram Abedi; Ali Tehranifar; Mehdi Parsa
Abstract
Introduction: Most plants have developed morphological and physiological mechanisms which allow them to cope with drought stress. Almost all the studies conducted on grapevines (Vitisvinifera L.) responses to drought conditions have focused on physiological responses such as stomatal reactions, photosynthesis ...
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Introduction: Most plants have developed morphological and physiological mechanisms which allow them to cope with drought stress. Almost all the studies conducted on grapevines (Vitisvinifera L.) responses to drought conditions have focused on physiological responses such as stomatal reactions, photosynthesis and osmotic adjustment, and biochemical responses like carbohydrates and proline. According to these studies, physiological and biochemical responses of grapevines to water stress are quite variable. This variability could be related to cultivar, time of the year, previous water stress level, intensity of stress, and environmental conditions. Osmotic adjustment in terms of compatible solutes accumulation has been considered as an important physiological adaptation for plant to resist drought, which facilitates the extraction of water from dry soils and maintenance of cell turgor, gas exchange and growth in very dry environments. Acting as compatible solutes as well as antioxidants, a significant rise in proline amount was observed in grapevine leaves under water stress conditions, suggesting that this amino acid has a protective role against the formation of excessive reactive oxygen species (ROS). Plants, in order to overcome oxidative stress, have developed enzymatic and non-enzymatic antioxidant defense mechanisms against scavenge ROS.
Materials and Methods: This research was conducted to assess the effect of different levels of irrigation on some characteristics of three cultivars of grapevine (Yaghooti, Bidanesefid and Askari), as a factorial based on a randomized complete block design in two years with four replications. The experiment started in June 21, 2014 and 2015. Water treatments were applied in four levels including: control plant (100% FC), moderate stress (60% FC), severe stress (30% FC) and rewatering treatment after severe stress treatment. Increase height, leaf number, stem diameter, leaf fresh and dry weight, stem dry weight, chlorophyll index,RWC, electrolyte leakage, soluble sugar, antioxidant activity, phenolic compound and proline were measured at the end of the experiment. JMP8 software was used to test the significant differences among the treatments and the interactions. When there were significant differences, means were separated by Tukey HSD test at the probability level p
Hamid Alipour; Mohammad Kafi; Ahmad Nezami; Amir Hossein Mohammadi
Abstract
Introduction: In Iran, main pistachio cultivation areas are located in the edge of desert. The major problem of these areas is the salinity of soil and irrigation water, which affects the growth and performance of plants and reduce yield.
Material and methods: In the present study, the effects of salinity ...
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Introduction: In Iran, main pistachio cultivation areas are located in the edge of desert. The major problem of these areas is the salinity of soil and irrigation water, which affects the growth and performance of plants and reduce yield.
Material and methods: In the present study, the effects of salinity on growth characteristics and mineral contents of seedlings of seven pistachio cultivars and three genotypes (Akbari, Ahmad-Aghaei, Kaleh-Ghoochi, Fandoghi, Badami, Ebrahimi, Seyfadini and G1, G2 and G3 genotypes) were evaluated. The study was conducted in split plot based on randomized complete block design in three replications. The main plots were salinity levels of the irrigation water (0.6, 15 and 30 dS/m) by adding sodium chloride to tap water, and the sub plots were the pistachio cultivars. After germination of seeds in the lab, the seedlings were transplanted into new vases in the greenhouse. At 3rd leaf stage, the salinity treatments were imposed for a period of four months. At the end of the experiment, all samples were collected for growth and cation contents of shoots and roots and data were analyzed by analysis of variance and correlation method, using SAS statistical software and Duncan’s Multiple Range Test was employed at probability level of 5%.
Results and discussions: The results showed that increasing salinity levels reduced stem, root and leaf dry weight as well as stem height and diameter. Salinity also caused a reduction in leaf number and leaf area. At the salinity level of 30 dS/m, dry weights of root and leaf decreased by more than 70%. The length and diameter of seedlings were decreased by 17.2 % and 37.9 % under the mentioned condition. According to the measured growth characteristics, Akbari and Kaleh-Ghoochi, considered as fast growing cultivars, while G3 genotype and Seyfoddini cultivar were considered as slow growing cultivars. By increasing salinity, sodium and calcium concentrations in root, stem and leaf increased significantly, and the ratio of potassium to sodium decreased in the mentioned parts of the plant. Fandoghi and Kaleh-Ghoochi cultivars accumulated the highest amounts of sodium in leaf, while G1 and G2 genotypes had the lowest sodium level. An important fact is that G3 variety had minimum stem and leaf sodium content and maximum root sodium content. In contrast, Kaleh-Ghoochi cultivar had maximum leaf sodium content and minimum root sodium content. This obviously indicates that G3 variety accumulates sodium in the root and avoids sodium transmission to stem and leaf, and Kaleh-Ghoochi variety acted conversely. G2 genotype and Kaleh-Ghoochi variety contain the highest (3%) and lowest (1.4%) levels of leaf potassium. At salinity levels of 15 and 30 dS/m, the index of potassium to sodium ratio decreased by 93% and 87%, respectively, in comparison to the control salinity level (0.6 dS/m2). Generally, local genotypes of pistachio (G1, G2 and G3) showed lower sodium absorption and transport to leaf, while G3 genotype had the highest sodium content in the root and the lowest concentration of sodium in stem and leaf. G2 genotype and Ahmad-Aghaei cultivar had the highest leaf potassium to sodium ratios of 7/8 and 6/3, respectively, while Kaleh-Ghoochi cultivar had the lowest leaf potassium to sodium ratio (3/95). It seems that Kaleh-Ghoochi, Fandoghi and Akbari cultivars are relatively sensitive and G1, G2 and G3 genotypes and Ahmad-Aghaei cultivar are relatively tolerant to salinity at seedling stage. Results of correlation analysis showed a significant negative correlation between the levels of salinity and growth characteristics of pistachio. Leaf sodium content has a significant negative correlation with leaf potassium content as well as the potassium to sodium ratio in root, stem and leaf. Reduced or stunted growth of the pistachio seedlings can be a result of water stress as well as sodium and chlorine toxicities. The impaired balance of nutrient uptake through the root in salt stress conditions leads to reduced growth characteristic of the pistachio seedlings. As the salinity of the irrigating water increases, concentrations of sodium and chlorine ions in soil solution increases, therefore, balance of nutrients is impaired and the root absorption of sodium and chlorine increases and potassium uptake decreases. Hence, the concentrations of sodium and chlorine ions increased in root, stem and leaf, andpotassium concentration decreased. Salinity tolerance in many plants is attributed to non-transmission or limited transmission of sodium to aerial parts of the plant. Various pistachio cultivars acted differently in absorption and accumulation of these elements in the parts of plant. The pistachio varieties with less sodium absorption and transmission to the leaf, but more potassium absorption and transmission, increased potassium to sodium ratio in the leaf and showed more tolerance to salinity. The mechanism is not clearly recognized, perhaps sodium is re-absorbed from the xylem sap and remained in the root and stem, without transmission to leaf. A similar mechanism probably occurs in local genotypes of pistachio (G1, G2, and G3) and results in improved tolerance to salinity.
