Response of Physiological Traits and Yield of Different Quinoa Cultivars to Waterlogging at Flowering Stage in Saline Soil

Abstract

【Background】 Quinoa is a dicotyledonous herbaceous plant in the genus of Chenopodiaceae. It originates from the Andes of South America and can tolerate abiotic stresses induced by low temperature, drought and salinity. FAO consider it the only plant which can meet the essential nutritional requirements of human body. As such, quinoa has attracted increased attention over the past decade, but there is a lack of understanding of how it responds to waterlogging. The eastern coastal areas in China are rich in tidal flats, and given the nutritional value of the quinoa and its high tolerance to abiotic stresses, these tidal flats are ideal places for quinoa in developing sustainable agricultural structure in these regions. 【Objective】 The objective of this paper is to experimentally investigate how different quinoa cultivars in these regions respond to waterlogging occurring at its anthesis stage. 【Method】 The experiments were conducted in pots and compared four cultivars which are abbreviated as SL 21, SL 44, SL 24, SL 45. The waterlogging was instigated at the anthesis stage and lasted for 4, 8 and 12 days respectively, with non-waterlogging taken as the control (CK). In each treatment we measured the physiological and yield traits of the plant, as well as the associated drainage indexes. 【Result】 Increasing waterlogging duration increased MDA of the quinoa leaves but reduced Chl(a+b), SP, SS, photosynthetic parameters (Pn, Tr, Gs, Ci) and chlorophyll fluorescence parameters (Fv/Fo, Fv/Fm). Compared to the CK, waterlogging for four days significantly increased the MDA in all four cultivars and reduced Chl(a+b) and SS in SL21 and SL24, with Pn, Fv/Fo and Fv/Fm not showing significant change. The waterlogging impacted the photosynthetic parameters of SL 24 and SL 45 more significantly than that of SL 21 and SL 44. Compared with the CK, waterlogging for 12 days significantly reduced the physiological indexes of all four cultivars and damaged their physiological metabolization. In terms of yield, the main spike yield of each plant accounted for more than 65% of its total yield. Waterlogging for four days significantly reduced the yield of each plant in the four cultivars, with the yield ranked in the order of SL 44>SL 21>SL 24>SL 45. Waterlogging for 8 days significantly reduced the main spike yield and the 1 000-grain weight; and waterlogging for 12 days failed the branch yield. 【Conclusion】 Among the four cultivars, SL44 is most resistant to waterlogging. For waterlogging occurring at the flowering stage, if taking yield reduction of 15%~20% as the standard for designing the drainage system, the allowable waterlogging duration should be less than 4.1 days.

Keywords

• quinoa
• waterlogging
• physiological characteristics
• yield
• drainage index