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.
Jafar Nabati; Elahe Boroumand Rezazadeh; Mohammad Zare Mehrjerdi; Mohammad Kafi
Abstract
Introduction: Conventional seed programmes take more than 10 years and diseases during each round of field multiplication become increasingly common and especially those transmitted through seed tubers. In contrast, the production of large volume of propagation material in protected environments requires ...
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Introduction: Conventional seed programmes take more than 10 years and diseases during each round of field multiplication become increasingly common and especially those transmitted through seed tubers. In contrast, the production of large volume of propagation material in protected environments requires only a few additional years of traditional seed multiplication in the field to produce the desired seed with an improved health status. This is useful especially in countries where there are no vector-free production areas for producing high quality potato seed tubers. In the last few decades, alternative seed production programmers have been developed in which the first multiplication steps are speeded up using in vitro plantlets, microtubers or minitubers. In the area of controlled environment agriculture (CEA), one of the most commonly discussed topics is lighting. The lighting system is generally the most expensive component of a controlled environment agriculture facility in terms of upfront costs as well as ongoing expenses (electricity use as well as replacement lamps). Naturally, advances in lighting technology are of great interest to the controlled environment agriculture community for these very reasons. Light emitting diodes (LEDs) are the most recent lighting technology to enter the controlled environment agriculture arena and have great potential to improve performance and reduce the overall cost of controlled environment lighting. Growth and morphogenetic effects of light (quality, intensity, and duration) and phytohormones are well documented, but their modes of action and mutual interactions are far from clear. One of the important questions is whether at least some of the morphogenetic effects of light are mediated by changes in phytohormone levels. This experiment was conducted in order to study the effect of different light sources on morphology and growth of potato plantlets under in-vitro conditions and their effect on minituber production in greenhouse to decrease energy consumption and production costs.
Materials and Methods: A factorial experiment was conducted based on completely randomized design with six replications under in-vitro conditions and four replications in greenhouse. Factors were consisted of cultivars (cv. Agria and Savalan) and light sources (LEDs emitting red, blue, white, combination of red and blue and also tubular fluorescent lamps as control). The experiment was carried out at the tissue culture laboratory of Yeka Seed Technology of Iran. Disease-free potato in vitro plantlets of Agria and Savalan cultivars were derived from the potato germplasm bank of Agricultural Biotechnology Research Institute of Iran. The plantlets were propagated using single-node cutting. Eight explants were cultured in sterilized culture vessels containing 30 ml of MS and pH was set to 5.8 before adding agar and autoclaving. Culture vessel were closed with polycarbonate caps and sealed with household plastic foil and were placed in a growth chamber at 24 °C and 16 h photoperiod for 4 weeks.
Results and Discussion: Results indicated that red spectrum caused an increase in plantlet height and Agria had a higher plantlet height under in-vitro conditions. Root length was higher in red-blue combination and no difference was observed between cultivars under in-vitro condition. The highest and lowest leaf area was obtained in white and red spectrum, respectively. Also, Savalan showed a higher leaf area in comparison with Agria. The lowest node number in plantlets was observed in red spectrum and the highest in white. The highest and lowest internode length was related to red and blue spectrum, respectively. Fluorescent light was resulted in the lowest plantlet fresh weight and no significant difference was observed among other treatments according to this parameter. Stem diameter and number of branches was not affected by different lights. Results of greenhouse study indicated that light conditions before transplanting of plantlets did not affected minituber number, while minituber weight was significantly affected by this factor and the lowest mean of this parameter was obtained in red spectrum compared to the other treatments.
Conclusion: Generally, results showed that less leaf area plantlet in vitro was also less leaf area in greenhouse (red light emitting diode). Leaf area is an important criteria for photosynthetic and biomass production. Therefore, in this experiment fresh and dry matter production was affected by this characteristics and red light showed the lowest dry matter production. LEDs could be considered as suitable light sources producing plantlets comparable with those grown under fluorescent light under in-vitro conditions along with saving energy and ultimately lower production cost.