| Salted land is one of the important agricultural reserves in China.Its governance and improvement are of great significance to solve the shortage of cultivated land and guarantee the national food security.Therefore,the efficient and rapid repair and improvement of salted land have become a major problem to be solved urgently,and the use of salt-tolerant plants to repair and improve salted land is one of the most effective ways to solve this problem.Iris lactea var.chinensis is a perennial ornamental plant,which has high adaptability,high salt tolerance and high ornamental value and so it is a rare saline soil restoration plant.In this study,the growth and physiological characteristics of seedlings of Iris lactea var.chinensis were studied under the condition of salt soil,the effects of different exogenous substances and soil improvement on the growth and physiological characteristics of Iris lactea var.chinensis were studied.The specific results are as follows.First of all,the growth and physiological characteristics of seedlings of Iris lactea var.chinensis were analyzed under salted soil conditions.The results showed that the growth rate of Iris lactea var.chinensis raised with the increase of soil salinity and growth time within 30 days in saline soil.After 30 days' growth on different soils,the root growth,plant survival rate and fresh weight of root were not significantly changed under the condition of 0.5%saline soil,and the root growth of Iris lactea var.chinensis significantly increased in 0.75%and 1%saline soil;the plant survival rate decreased significantly,and the fresh weight of shoot and root of Iris lactea var.chinensis were significantly decreased.The activities of POD and CAT in the shoots of Iris lactea var.chinensis were not significantly affected by 0.5%saline soil.The POD activity and CAT activity of shoots of Iris lactea var.chinensis decreased significantly in the 0.75%saline soil.In order to explore the measures to promote the growth of seedlings of Iris lactea var.chinensis in salt soil,the effects of different exogenous substances on the growth and physiological characteristics of seedlings of Iris lactea var.chinensis were analyzed by leaf spraying method.The results showed that the application of ALA,SA and SNP could promote the elongation of the shoots in 0.5%saline soil,and the application of SA and ABA could promote the elongation of the shoots in 0.75%saline soil,ALA,ABA and SNP can promote the elongation of the shoots in 1%salt soil.The application of SA and SNP could significantly increase the shoots fresh weight of the seedlings,and the application of SNP could effectively increase the fresh weight of the roots of the seedlings.The effects of exogenous substance treatment on the contents of soluble protein and SOD were not significantly affected by exogenous material treatment,but the exogenous SA significantly increased POD activity in 0.5%saline soil,and the exogenous ALA increased CAT activity of seedlings in 0.5%saline soil.The effects of peat and garden soil on the growth and physiological characteristics of seedlings of Iris lactea var.chinensi.under high salt soil conditions were analyzed by adding different amounts of peat and garden soil in saline soil.The results showed that the difference of plant heirght between the addition of the garden soil treatment group and the control group increased with the increase of the adding amounts of the garden soil.Under the condition of 1%saline soil,the effect of addition of 1/12 peat and 1/6 peat on the plant height was the best,followed by addition of 1/4 peat.The addition of 1/6 peat can also significantly promote the elongation of roots of Iris lactea var.chinensis in high salt conditions,and the addition of peat could significantly improve the survival rate of Iris lactea var.chinensis,the fresh weight and soluble protein content of seedlings of Iris lactea var.chinensis in 1%saline soil,but does not affect the SOD,POD and CAT activities.The addition of 1/6 soil could significantly increase the fresh weight,POD activity and root CAT activity in 1%salt soil,but does not affect the soluble protein content and SOD activity.The results of the above studies showed that the growth and partial physiological metabolism of seedlings of Iris lactea var.chinensis were inhibited in 0.75%,1%and 0.5%saline soil.The application of ALA,SA and SNP could promote the aboveground growth of the Iris lactea var.chinensis,ALA and S A could improve the antioxidant enzyme activity in the shoots of Iris lactea var.chinensis.In the 1%salt soil,the addition of garden soil could effectively promote the growth of shoots and increase the activity of antioxidant enzymes,among which the effect of adding 1/6 garden soil was the most obvious.The addition of peat can effectively promote the growth of shoots and roots of Iris lactea var.chinensis,and the effect of adding 1/6 peat is the most obvious. |
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