Effects of Exogenous Organic Acids on Physiological Characteristics of Cotton Roots and Organic Acids in Root Exudates in Saline Soil at the Seedling Stage
To study the effects of adding different concentrations of organic acids on physiological charac-teristics and organic acids in root exudates of cotton at the seedling stage by using two kinds of saline-alkali soils collected in Jishi County,Kashgar City,with salinity of 12.8 g/kg(medium saline-alkali soil)and sa-linity of 19.3 g/kg(heavy saline-alkali soil).The addition concentrations of 5 mmol/L and 10 mmol/L or-ganic acids were set,and four organic acids,oxalic acid,acetic acid,ascorbic acid,and formic acid were added respectively,with no organic acid added as the control group.A total of 18 treatments were performed.Then the effects of adding different kinds of organic acids under saline-alkali soil on the contents of malon-dialdehyde,osmotic regulator,antioxidant enzyme,and organic acids in pot experiment cotton were stud-ied.The results showed as follows:With the increase of salinity,exogenous organic acids could significant-ly reduce soil pH(P<0.05),the contents of malondialdehyde,soluble sugar,and soluble protein proline in cotton root at the seedling stage increased,and the content of malondialdehyde in cotton root after exoge-nous organic acid treatment was significantly decreased(decreased by 11.4%-38.4%)(P<0.05),and the activities of osmoregulatory substances and antioxidant enzymes were significantly increased(P<0.05).The composition of organic acids in root exudates of cotton at a seedling stage significantly promo-ted oxalic acid secretion(P<0.05),indicating that oxalic acid was the main organic acid responding to salt and alkali.According to the above indexes,exogenous oxalic acid,acetic acid,ascorbic acid,and formic acid can alleviate the damage of saline-alkali soil in the cotton seedling stage,and the addition of 5 mmol/L ox-alic acid has the best effect.
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