Effects Of Different Soil Amendments On Growth And Physiological Characteristics Of Pakchoi Under Salt Stress

The growth of Pakchoi(Brassica campestris ssp.chinensis L.)is sensitive to salt,and salinized soil seriously affects its normal growth.As a cementing agent to alleviate soil salinization and agglomerate soil particles,soil amendment has the advantages of strong stability and low cost.But there are many kinds of special products.Therefore,the effects of polyacrylamide(PAM),polyacrylic acid(PAA)and?-polyglutamic acid(?-PGA)on the growth and physiological metabolism of Pakchoi were studied in this paper by adding Na₂SO₄to simulate salt stress with pot culture of Pakchoi,so as to provide theoretical guidance for high-quality and high-yield cultivation of Pakchoi in saline alkali soil.The main results are as follows:1.Under Na₂SO₄stress,the three soil amendments could promote the emergence of Pakchoi seedlings,increase plant height,root length and fresh weight,among which?-polyglutamic acid(?-PGA)had the best effect.The emergence rate of Pakchoi seedlings in normal soil and Na₂SO₄stressed soil increased by 10 percentage points and 29 percentage points respectively when the application rate was 4 kg/667m².2.Under salt stress,the chlorophyll content(SPAD readings)of Pakchoi was the highest at the dosage of 8 kg/667m²polyacrylic acid(PAA),which was 19.4%higher than that of the control;The application of 4 kg/667m²?-polyglutamic acid(?-PGA)could significantly increase the net photosynthetic rate of Pakchoi leaves,and the application of 4 kg/667m²polyacrylamide(PAM)could significantly increase the transpiration rate of Pakchoi leaves.3.The activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)in Pakchoi leaves increased under salt stress,the optimal dosage of?-polyglutamic acid(?-PGA)was 4 kg/667m²;When the dosage of polyacrylic acid(PAA)was 8 kg/667m²,the MDA content of Pakchoi leaves under salt stress was reduced by 35.6%.4.Under salt stress,a lot of osmotic adjustment substances were accumulated in Pakchoi,the content of soluble sugar and proline of?-polyglutamic acid(?-PGA)increased by 25.4%and 64.9%compared with CK;application of 4 kg/667m²polyacrylic acid(PAA)increased the soluble protein content of Pakchoi leaves by 17.8%under salt stress.In summary,application of 4 kg/667m²soil amendment?-polyglutamic acid(?-PGA)could promote the growth of pakchoi,increase the activity of antioxidant enzymes,increase the content of osmotic regulators and alleviate the injury caused by salt stress.