Abstract:

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 accumulation of putrescine(Put).Under 40 mmol/L saline-alkali stress,exogenous application of 40 μmol/L SA reduced malondialdehyde(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%,respectively.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 antioxidant 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.

Key words: Red kidney bean, Salicylic acid, Polyamines, Combined saline and alkaline stress, Seedling growth

CLC Number: 

• Q945植物生理学

• S643.1