Effect of Mycorrhizal Fungi Symbiosis and Foliar Application of Amino acids on Some Growth Traits and Pot Marigold Oil (Calendula officinallis L.)

The Food and Drug Administration has classified pot marigold as a GRAS (generally recognized as safe) substance. Foliar nutrition acts as an effective tool for nutrient management in plants, and foliar nutrition can be used successfully to address wide spread nutrient deficiencies, especially in critical plant growth stages. Plants are able to absorb amino acids, amides and many nitrogen compounds through their roots or leaves. Also, plant symbiosis with mycorrhizal fungi causes water absorption, nutrient uptake and growth under environmental stress. These fungi are able to symbiosis with the roots of most terrestrial plants.

In order to investigate the effects of foliar application of amino acids and mycorrhizal fungi symbiosis on quantitative and qualitative characteristics of Calendula officinalis L., a factorial layout has been conducted, based on a randomized complete block design with three replications at the research farm of Islamic Azad University, Takestan Branch during 2017-2018 and 2018-2019 growth seasons. Experimental factors included three species of mycorrhiza fungi (Control, Glomus mosseae, G. etunicatum and G. intraradices) and Soren amino acid levels (This commercial compound contains a variety of essential amino acids for the plant) included no foliar application and foliar application in two stages of stem and flowering. Land preparation was performed before planting. According to the experimental map, experimental plots were planted in six rows at a distance of 50 cm and a length of six meters and the distance between plants on the row was 20 cm. Before planting, based on soil test results, ammonium phosphate fertilizer (150 kg.ha-1) and potassium sulfate fertilizer (100 kg. ha-1) were used. Both fertilizers were mixed with soil along with one third of the nitrogen mountain from the urea source at the beginning of planting. Urea fertilizer at the rate of 100 kg.ha-1 was applied and the remaining two thirds were applied as a road after the final thinning and before flowering.

The results showed that the application of amino acid and mycorrhizal fungus of G. mosseae species had a so significant increase in the percentage of root colonization compared to the treatment of not using mycorrhizal fungus and the application of amino acid. Foliar application of amino acid increased by 6% and use of mycorrhiza, G. mosseae in pot marigold, increased chlorophyll index treatment by 33%. The results also showed a 25% and 70% increase in oil percent and oil yield due to foliar application of amino acid and use of mycorrhiza, G. mosseae compared to non-use, foliar application of amino acid and mycorrhiza. The highest essential oil yield was obtained from G. mosseae treatment with a value of 7.74 kg.ha-1. The results of analysis of variance showed that the interaction effect of foliar application of amino acid and mycorrhiza on the percentage and oil yield was significant at the level of five percent. The results showed a 25% and 70% increase in oil yield and yield due to foliar application of amino acid and mycorrhiza, respectively, of G. mosseae compared to non-foliar application of amino acid and mycorrhiza. Inoculation with G. mosseae and application of amino acid had the highest seed yield and this treatment showed a 24% increase compared to the control with the same mycorrhiza but without the use of amino acid.

Based on this study results, it can be said that inoculation of pot marigold with mycorrhizal fungus, especially G. mosseae species, it can be used to absorb nutrients for better growth of this plant, and foliar application of amino acids improves plant growth and development by providing nitrogen to the plant.