Effects of salt stress on growth of Barringtonia racemosa and absorption and translocation of mineral elements in it

【Objective】 In order to explore the effects of salt stress on the growth of Barringtonia racemosa seedlings and the absorption and translocation of mineral elements, study salt stress tolerance of B. racemosa from the perspective of ion transport mechanism, and to provide protection, ex situ conservation, promotion and utilization of B. racemosa wild populations, and site selection during afforestation scientific basis.【Method】 This study used two-year-old B. racemosa seedlings as the test material, and adopted an automatic tide simulation all-diurnal tide device. This study set up 7 salt stress treatment groups, namely 0(CK), 15‰, 20‰, 25‰, 30 ‰, 35‰, 40‰, and comprehensively analyzed absorption, translocation coefficients and correlation of mineral elements calcium(Ca), magnesium(Mg), iron(Fe), chlorin(Cl) and sodium(Na) in B. racemosa roots, stems and leaves under salt stress.【Result】 B. racemosa plants grew well under low salinity(0-15‰) stress conditions, and high salinity(30‰-40‰) salt stress conditions caused rapid leaf shedding and reduces in biomass, which severely inhibited the growth and development of B. racemosa plants. Salt stress increased the accumulation of Na and Cl in B. racemosa plants, absorption of Ca and Mg in the roots of B. racemosa seedlings decreased, while the leaf parts increased the absorption of Ca, Mg, and Fe. There is no significant change in the absorption of Ca, Mg and Fe in stem parts. Under salt stress, the translocation coefficient of B. racemosa seedlings for Ca, Mg, and Cl were all greater than 1.0, the translocation coefficient for Fe was less than 1.0, and the translocation coefficient for Na was greater than 1.0 when the salinity was 35‰-40‰. There was a negative correlation between the biomass and the above-ground elements, and the leaf abscission rate, root-shoot ratio and the above-ground elements were all positively correlated.【Conclusion】 The seedlings of B. racemosa grow well in the water salinity range of 0-15‰ under the environment of full-day tide flooding for 6 h/d, and have certain tolerance in the range of 20‰-25‰ salinity. When the water salinity is ≥30‰, B. racemosa seedlings cannot grow normally. The salt tolerance is mainly achieved by the accumulation of Na in the root system, restricting the transportation of Na to the stems and leaves, and enhancing the transport of Ca, Mg, Fe, and Cl to the stems and leaves. In the process of ex situ conservation of B. racemosa, the salinity level can be used as an important factor in site selection. At the same time, when semi-mangrove plantation in tropical and subtropical areas is carried out, B. racemosa should be planted in areas with high tide and medium and low salinity.