外源水杨酸对复合盐碱胁迫下红芸豆幼苗生长的缓解效应OA

To investigate the physiological regulatory role of salicylic acid(SA)in alleviating saline-alkali stress in kidney bean seedlings and to provide a basis for stress-resistant cultivation of kidney beans in typical saline-alkali areas of Shanxi Province,kidney beans were used as the test material.A composite saline-alkali stress system with a ratio of NaCl,Na2SO4,NaHCO3,and Na2CO3 of 1∶9∶9∶1 was used to simulate saline-alkali stress.Five concentration gradients of 0(CK),20,40,60,and 80 mmol/L were set to screen for the optimal concentration of salt-alkali stress treatment.Subsequently,based on the selected concentration,three SA concentrations(20,40,and 60 μmol/L)were applied simultaneously to study the mitigating effect of SA on kidney bean seedlings under saline-alkali stress.The results indicated that under 40 mmol/L salt-alkali stress,the growth of red kidney beans was significantly inhibited but did not reach lethal or severe stress levels,making it the optimal salt-alkali stress concentration.Stress at this concentration induced oxidative damage in early seedlings,inhibited nutrient absorption and translocation,increased the activities of arginine decarboxylase(ADC)and ornithine decarboxylase(ODC),and led to excessive accumula-tion of putrescine(Put).Under 40 mmol/L saline-alkali stress,exogenous application of 40 μmol/L SA reduced ma-londialdehyde(MDA)content in leaves and roots by 37.63％and 39.76％,respectively;hydrogen peroxide(H2O2)content by 38.71％and 21.13％,respectively;and superoxide anion(O2-)content by 40.00％and 52.17％,re-spectively.Root activity increased by 56.14％.The Na content in both leaves and roots significantly decreased,while the contents of K,Cu,Ca,and Fe significantly increased.Furthermore,exogenous application of 40 μmol/L SA reduced the activities of ADC and ODC,increased the activity of S-adenosylmethionine decarboxylase(SAMDC),and promoted the conversion of Put to spermidine(Spd)and spermine(Spm),thereby enhancing the plant's antioxi-dant capacity and ion homeostasis regulation.In conclusion,exogenous salicylic acid can effectively alleviate the physiological damage caused by composite saline-alkali stress in kidney bean seedlings by activating the antioxidant system,optimizing polyamine metabolism,and promoting the absorption and distribution of mineral elements.