An adaptive abiotic stresses strategy to improve water use efficiency, quality, and economic benefits of Panax notoginseng: Deficit irrigation combined with sodium chloride

Abstract

It is still a long-term challenge to decrease root rot and improve saponin content of Panax notoginseng, thus economic benefits in Guangxi and Yunnan provinces, China. The objective of this study was therefore to propose a promising abiotic stresses strategy: deficit irrigation combined with sodium chloride (DISC) to cope with the challenge. A two-year field experiment was conducted to explore the effects of deficit irrigation combined with sodium chloride on physiological traits, yield, quality attributes, water use efficiency, and economic benefit of Panax notoginseng in 2018 and 2019. Experiment treatments consisted of two deficit irrigation levels [DL, light deficit level: irrigation upper∼lower limit (80–65 %)θFC; DM, moderate deficit level: irrigation upper∼lower limit: (70–55 %)θFC, where θFC represents field capacity] and five NaCl application rates [0 (C0), 15 (C1), 30 (C2), 45 (C3), and 60 (C4) mmol L−1], respectively. All treatments were designed using a randomized complete block with three replications. The results indicated that DISC could significantly promote the physiology and growth of Panax notoginseng and improve yield, quality and economic benefits under micro-sprinkler irrigation and shaded conditions in 2018 and 2019. Compared with the DMC0 and DLC0 treatments, DLC1 treatment significantly improved net photosynthetic rate (Pn), stomatal conductance (Gs), root (kr), shoot (ksh), and canopy (kc) hydraulic conductance of Panax notoginseng. The DLC1 treatment significantly increased root length, surface area, average diameter, and volume of root of Panax notoginseng compared with the DMC0 and DLC0 treatments. The DLC1 treatment significantly improved rood dry matter, yield, saponin content of Panax notoginseng, water use efficiency, and economic benefits by decreasing the incidence of root rot, but reverse results were observed in the DLC2, DLC3, and DLC4 treatments. Therefore, this study suggested that deficit irrigation amount [DL, (80–65 %)θFC] combined with NaCl concentration (C1, 15 mmol L−1) should be recommended as an appropriate agronomic management strategy to alleviate root rot and improve water use efficiency, saponin content, economic benefits of Panax notoginseng in the seasonally arid region of Southwest China.