Response of Growth, Yield and Essential Oil of Geranium Plants to Surface Irrigation and Humic Acid Treatments

Abstract

Water is among the most important factors affected growth, yield and quality of medicinal and aromatic plants since its deficiency may cause serious growth harms and yield losses. Egypt suffers from a scarcity of water, so each drop should be preserved. Therefore, the objective of the present study was to determine the suitable irrigation treatment (120, 100 and 80% ETo (evapotranspiration) and humic acid amounts (control), 1.0, 1.5 and 2.0 cm/L) that attain the highest growth, yield and essential oil of geranium (Pelargonium graveolens L. Herit Aiton) under surface irrigation in clay soil at El Kanater El Khairiya. Results showed that humic acid alleviated the deteriorative effect of water deficiency, where plants irrigated with 120% ETo and treated with 2.0 cm/L humic acid improved the growth characters in terms of plant height, number of branches, fresh, dry weights and volatile oil yield. While, the highest volatile oil percentage and proline content were recorded at 80% ETo with humic acid at 2.0 cm/L treatment during the two growing seasons. Results also showed that the applied irrigation water under 120% ETo treatment was 7192 m3/fed averaged over the two growing seasons attained the highest yield. The highest values of water use efficiency and water productivity were 14.1 and 10.0 averaged over the two growing seasons attained under 80% ETo and application of 2.0 cm/L humic acid. Thus, it can be concluded that the required irrigation water for geranium is under 120% ETo. However, under water deficiency, 80% ETo and 2.0 cm/L humic acid could be applied, which increase geranium yield by 24%, compared to the 120% ETo treatment averaged over the two growing seasons.

Role of Humic Acid on Inducing Salt Tolerance of Ivy Geranium (Pelargonium peltatum L.) Plants

“…HA application improved hormonal and ROS balance [46]; as well as activation of antioxidant enzymes and accelerating organic solute accumulation [47], which was ultimately reflected in plant growth [22]. Moreover, the encouraging role of HA can be linked to its impact on boosting interior carbon dioxide concentration and leaf thickness, improving cell water maintenance and boosting water use efficiency [30]. Additionally, HAs' positive effect could be due to the hormone-like activity or may be connected to encouraging indole acetic acid assimilation, which accelerates cell division and enlargement as well as eradicating ROS [48].…”

“…Nofal et al [29] found that the spraying of HA significantly increased Erantheumum pilchellum plant height, leaf number per plant, fresh and dry weight, flower diameter and chlorophyll content. Hammam et al [30] revealed that spraying geranium plants with HA significantly increased plant height, shoot fresh and dry weight, proline concentration and water use efficiency. Previous research has suggested that the beneficial effects of HA can be attributed to the activation of several metabolic enzymes, improving plant water status, maintaining ion and redox homeostasis and promoting secondary metabolite assimilation [31].…”