Effects of organic acids on photosynthetic characteristics and physiological indexes of cotton at boll stage in saline-alkali soil
In order to explore the effects of adding different concentrations of organic acids on photosynthetic characteristics and physiological indexes of cotton in the bolling stage,a pot control experiment was carried out at Xinjiang Agricultural University in 2023.Two kinds of saline-alkali soils from Jishi County,Kashgar City,with a salinity of 12.8 g·kg-1(moderate saline-alkali soil)and salinity of 19.3 g·kg-1(severe saline-alkali soil)were used.Two organic acid additive concentrations of 5 mmol·L-1 and 10 mmol·L-1 were set,and four organic acids,oxalic acid(C1),acetic acid(C2),ascorbic acid(C3)and formic acid(C4),were added respectively.No organic acid(CK)was added as the control group.The effects of organic acids added to saline-alkali soil on photosynthetic characteristics,leaf SPAD,leaf and root enzyme activities,and root growth of cotton were studied.The results showed that the organic acid treatment significantly increased the net photosynthetic rate of cotton in the moderate saline-alkali soil,in which 5 mmol·L-1 acetic acid treatment had the best effect,which increased by 122.2%.Oxalic acid,acetic acid,and formic acid treatment significantly increased the SPAD value of leaves,and 10 mmol·L-1 acetic acid treatment had the highest SPAD value.Under moderate salt stress,5 mmol·L-1 oxalic acid,acetic acid,and ascorbic acid significantly promoted the activities of peroxidase(POD),catalase(CAT),superoxide dismutase(SOD)and ascorbate peroxidase(ASA-POD)in leaves and roots.For 10 mmol·L-1 organic acid treatment,acetic acid and formic acid inhibited POD and CAT activities.Under severe salt stress,each organic acid treatment had a more significant effect on the improvement of antioxidant enzyme activity of cotton,among which 5 mmol·L-1 oxalic acid,acetic acid,and ascorbic acid showed a significant promotion effect on all enzymes,but 10 mmol·L-1 ascorbic acid inhibited the activity of root CAT.For cotton root morphology,only 5 mmol·L-1 ascorbate treatment in moderate saline soil and 10 mmol·L-1 ascorbate treatment in severe saline soil significantly promoted root growth.Based on the above studies,it is recommended to add 5 mmol·L-1 acetic acid as a saline-alkali soil amendment.
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