The Effects Of Plant Retardant On Phenotypic Plasticity Of Hedysarum Laeve Under Drought And Saline-alkali Stress

This study analysis the influence of different concentrations(0 mg/L,150 mg/L,300 mg/L,450 mg/L and 600 mg/L)plant retardant on the growth characteristics of Hedysarum laeve under severe saline-alkali treatment(total salt content of 0.94 g/kg)with water treatment as control(CK)by simulating actual Mu Us sandy land saline conditions.In order to provide a theoretical basis for the more widely planting Hedysarum laeve in the Mu Us sandy land.The physiological indexes,morphological indexes and biomass of the Hedysarum laeve were studied under different concentrations of plant retardant after saline-alkali stress.The results showed:(1)Different growth periods of tolerant ability of saline-alkali stress of Hedysarum laeve were different.The three kinds of saline-alkali stress could hinder growth of root elongation,reduced binding strength and area of branch roots and soil in the vigorous growth period.Light saline-alkali stress could stimulate root growth and promote the root growth,but Hedysarum laeve would produced stronger sensitivity under severe moderate and saline-alkali stress in the end growth period.The surface area of root was 52.05% of CK under severe saline-alkali stress in the end growth period.The inhibition effect of mild and moderate saline-alkali stress on Hedysarum laeve was not significant(P>0.05),while severe saline-alkali stress could significantly inhibit the growth of Hedysarum laeve(P<0.05).The plant height,basal diameter growth and crown growth and the number of branches decreased,root surface area,the root length,root number and root morphology indexes decreased,the inhibitory effect of hedysarummaxim biomass were quite obvious under severe saline-alkali stress.(2)A certain concentration range of plant retardant could control the growth indexes effectively under severe saline-alkali stress.With the increase of treatment concentration,the plant upper part configuration showed a short,sturdy and multi branched structure.(3)Plant retardant could reduce plant height,promote base diameter thickening and tillering,increase root growth and development,promote quality of each part,and reduce root/shoot ratio and DW/GE ratio of each part under drought conditions.After 450 mg/L treatment,the height was 3.03 cm and the root length was 408.55 cm.The total biological fresh weight and the total biological dry weight were 6.83 g and 2.24 g respectively.It was found that the optimum concentration of plant retardant was 450 mg/L to improve the drought resistance of Hedysarum laeve by comprehensive analysis of morphological and biological indexes.