Parvaneh Yousefvand; Asghar Mosleh Arani; Afagh Tabandeh Saravi
Abstract
Introduction: Climate change has great impact on global production of several major plants. Negative effects of increasing carbon dioxide concentration in the world, on the one hand, and positive effects of the gas on plants, on the other hand, are the most important reasons for investigating the gas ...
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Introduction: Climate change has great impact on global production of several major plants. Negative effects of increasing carbon dioxide concentration in the world, on the one hand, and positive effects of the gas on plants, on the other hand, are the most important reasons for investigating the gas effects on different plants. Many studies have been conducted to examine the effects of elevated CO2on plants during the past several decades. Carbon dioxide enrichment in greenhouses can be used as a mechanism for reducing production time, improving quality and increasing plant vigor. The world is facing an increase in the concentration of carbon dioxide in the coming years. The physiological responses of plant are affected by CO2concentration,among which changes in nitrogen, chlorophyll content, proline and soluble sugar have been observed in many studies. The significant changes in the levels of these characteristics are likely to cause marked effects on the entire metabolism of plant. Since the proteins of the Calvin cycle and thylakoid represent the majority of leaf nitrogen, chlorophyll content is the central part of the energy manifestation and can directly determine photosynthetic response and primary production. This study was aimed to investigate the effects of elevated concentration ofCO2 on some morphological and physiological traits of Melia azedarachunder greenhouse conditions. .
Materials and Methods: The experiment was conducted in a CO2 – controlled glasshouse in a completely randomized design with three replications in Yazd University. The glasshouse consisted of three separate chambers with threeCO2levels of control (450 ppm), 750ppm, and 1100ppm.The concentration of CO2within each chamber was monitored constantly three times a week. After two months, morphological characteristics such as diameter of the collar, height of stem, number of leaves, wet weight of shoots, root wet weight, wet matter biomass, dry weight of shoots, root dry weight, dry matter biomass, and physiological characteristics including proline content of leaves, soluble sugar of leaves, a andb chlorophyll content, total chlorophyll content, carotenoid, nitrogen, phosphorus, potassium and water content of leaves were measured. To analyze the data, normality was assessed using Kolmogorov–Smirnov test. Analysis of variance was performed to detect the difference between the different levels of treatment for all traits. Difference among treatments means were compared by using Duncan test. All the analyses were performed using SAS statistical software.
Results and Discussion: The results showed that CO2at the concentrations of 750 and 1100 ppm affected significantly all the measured morphological properties except for plant height, root dry weight and physiological traits such as proline, N, and leaves relative water content. However, CO2concentration of 750 ppm had the highest effect on the studied parameters, so that mean dry weight of shoot, dry matter biomass and proline increased up to more than three times, and shoots and roots wet weight and wet matter biomass increased up to more than two times compared to control. The greatest diameter of the collar and the amount of nitrogen were observed at 750 ppm concentration. Concentrations of 750 and 1100 ppm caused a significant increasein the number of leaves (up to two times) and the height of stem compared to control. The increase observed inmorphological characteristics may be owing to photosynthesis stimulation during the experiment in CO2-elevated chamber. Soluble sugar as an important product of photosynthesis increased but the differences were not significant. Soluble sugar may be used for synthesis of morphological characteristics.
Conclusion: Growth of Melia azedarach in elevated-CO2 chamber strongly reacted to theincrease in photosynthesis. Therefore, based on the results of this study,CO2 elevation in glasshouse can be proposed for increasing the growth of plant. Consideringthe continued increaseinCO2 concentrations as a result ofcontinued use of fossil fuels in the word, cultivation of Melia azedarach in urban areas seems an appropriate option. The results of the present study also showed that there is not generally a significant difference between CO2concentrations of 750 and 1100 ppm in Melia azedarach. Therefore, it can be concluded that CO2 up to 750 ppm can cause a significant increase in the growth of this species, because no significant effect was observe between the two concentrations (750 and 1100 ppm) on growth factors.
