Journal of Soil and Plant Interactions

Abstract

One of the research requirements in agriculture is to find a new and practical method for sustainable production that brings the highest efficiency and the least harm to humans and the environment. In order to investigate the effect of different levels of carbon dioxide and ethanol foliar spraying on the physiological and biochemical characteristics of basil (Ocimum basilicm cv. Keshkeni luvelou), a factorial pot experiment based on a completely randomized design with three replications was conducted in the research greenhouse of the Department of Horticultural Sciences and Landscape of Ferdowsi University Mashhad in 2018. The factors included ethanol spraying at 4 levels (0, 10, 20, and 30% v/v) and carbon dioxide at 3 levels (380, 700, and 1050 µmol mol−1). The results showed that the highest relative water content (RWC) of leaf, photosynthesis rate, transpiration rate, stomatal conductance, and leaf protein were observed in the treatment of 20% v/v ethanol foliar application with the application of 700 µmol mol−1 of carbon dioxide, as they increased by 45%, 295%, 684%, 83%, and 328% compared to the control, respectively. Fresh and dry biomasses of shoot parts increased significantly with increasing carbon dioxide concentration and ethanol spraying. Thus, the highest fresh and dry biomasses of shoot parts were obtained in foliar spraying of 30% v/v of ethanol and 700 µmol mol−1 of carbon dioxide which increased by 176% and 76%, respectively, compared to the control. The highest activity of polyphenol oxidase and guaiacol peroxidase, stomatal resistance, and electrolyte leakage were related to spraying 30% v/v of ethanol with an application of 1050 µmol mol−1 of carbon dioxide which showed an increase of 2%, 4%, 65%, and 76%, respectively, compared to the control. Overall, the results showed that foliar spraying of 20 and 30% v/v of ethanol along with the application of 700 µmol mol−1 carbon dioxide had the greatest effect in increasing photosynthesis and finally the fresh and dry biomasses of basil.

Methods: A pot experiment was conducted as a factorial experiment based on a completely randomized design with three replications in the research greenhouse of the Department of Horticultural Science, Faculty of Agriculture, Ferdowsi University of Mashhad in 2018. Experimental factors included ethanol foliar application at 4 levels (0, 10, 20, and 30% v/v) and carbon dioxide at 3 levels (380, 700, and 1050 µmol mol−1). The plants were harvested at the flowering stage to evaluate some physiological and biochemical characteristics including photosynthesis rate, transpiration rate, stomatal conductance, leaf relative water content (RWC), leaf protein, electrolyte leakage, polyphenol oxidase activity, guaiacol peroxidase activity, and stomatal resistance. Minitab17 software was used to analyze the data and the mean comparison was performed based on the Bonferroni test (p < 0.05).

Results: The results showed that the highest leaf RWC, photosynthesis rate, transpiration rate, stomatal conductance, and leaf protein were observed in the treatment of 20% v/v ethanol foliar application with the application of 700 µmol mol−1 of carbon dioxide. In addition, the highest polyphenol oxidase and guaiacol peroxidase activities, stomatal resistance, and electrolyte leakage were obtained in the treatment of 30% v/v ethanol application with a 1050 µmol mol−1 of carbon dioxide. The fresh and dry biomasses of shoot increased significantly with increasing carbon dioxide concentration and ethanol spraying. Thus, the highest fresh and dry biomasses of shoot were obtained in the foliar spraying of 30% v/v ethanol with the use of 700 µmol mol−1 carbon dioxide.

Conclusions: In this study, the results showed that all the studied traits were affected by ethanol foliar spraying and elevated carbon dioxide. Furthermore, the results showed that foliar application of 20 and 30% v/v of ethanol with the application of 700 µmol mol−1 of carbon dioxide had the most effect on the studied characteristics. Besides, the control treatment (without ethanol foliar application and carbon dioxide injection) had the least significant effect on the studied traits. Overall, the results of this research showed that foliar spraying of 20 and 30% v/v of ethanol with the application of 700 µmol mol−1 carbon dioxide had the greatest effect in increasing photosynthesis rate and the fresh and dry biomass of basil plants.

References:
1. Khosravi, M.T., Mehrafarin, A., Naqdi Badi, H.A., Haji Aghaei, R., Khosravi, A., 2011. The effect of methanol and ethanol on the performance of Echinacea purpura in Karaj. J. Med. Plant Res. 2(2), 128–121.