The effect of foliar application of chitosan and shrimp shell powder on photosynthetic pigments, some growth parameters and essential oil of the medicinal plant Hyssopus officinalis

One of the methods to increase the secondary metabolites production in plants is to use elicitors and chitosan is a biotic elicitor obtained from the deacetylation of chitin in the outer shell of crustaceans such as shrimp. Shrimp shell is part of shrimp solid waste discarded in large amount every year. This research was carried out to investigate the effect of foliar application of chitosan elicitor (0.25 and 0.5 g/l) and shrimp shell powder (2.5 and 5 g/L) on medicinal plant Hyssopus officinalis in potted form at the Experimental Farm of Islamic Azad University, Shahre-kord Branch during spring to fall in 2017. The essential oils were obtained from aerial part of hyssop by Clevenger device. The essential oils were analyzed by GC-FID and GC/MS. Totally, 33 compounds و representing more than 89-95% of the oil composition, were identified. The predominant components of the essential oil in all treatments were cis-pinocamphon (43.19-55.09%) and beta-pinene (8.31-15.04%). Foliar application of chitosan, shrimp shell, and shrimp shell × chitosan increased the percentage of essential oil and cis-pinocamphon, but only the effect of chitosan 0.5 was statistically significant. Chitosan treatments decreased plant height, shoot fresh and dry weight, chlorophyll a, chlorophyll b and total chlorophyll of hyssop but shrimp shell and chitosan × shrimp shell solutions increased them, although no one was significant. According to the results of this study, it seems that in addition to chitosan, shrimp shell with higher concentrations can be used to increase effective substances of the medicinal plant Hyssopus officinalis.