The Calcium Treatment Effect On Potato Main Constituent And Physiological&Biochemical Indicator During Storage Period

Take potato variety Shepody and Kexin1#as the experimental materials, to research the effect of calcium ion on cell membrane and cell wall in order to provide the reference basis of Ca2+rational use on potato storage. Processing the soaking of potato by0.5%and1.0%Ca(NO3)2solution, survey and evaluate the Relative Conductivity, MDA content, Peroxidase activity, Cellulose content, Cellulase activity, Protopectin content, Water-soluble Pectin content and Pectinase activity in the potato tubers during the storage period respectively, to analysis the calcium ion effect on cell membrane function and cell wall main ingredient; simultaneously determine the Dry Matter content, Starch content, Reducing Sugar content, Soluble Protein content and Amylase activity in tubers respectively, and research the effect of postharvest soaking of calcium on the potato tubers quality; respectively survey and evaluate the Relative Conductivity, MDA content, Peroxidase activity, Cellulose content, Cellulase activity, Protopectin content, Water-soluble Pectin content and Pectinase activity in tuber after the field spraying and postharvest soaking treatment, in order to explore the different duration calcium treatment impact on potato physiological and biochemical characteristics; use paraffin method to observe the tuber tissue sectioning to explore the effect of soaking treatment on the cell wall thickness and starch grains size&number in the cell of potato after90days with complete soaking treatment. The results show that:The potato with different concentrations calcium treatment its membrane related physiological indexes changing situation after127days storage as:the relative conductivity for tuber with1%calcium treatment is79.74%, significantly decreased than CK (P<0.01), and MDA content is0.36mmol/g-FW, significantly lower than CK (P<0.05); The peroxidase activity for tuber with0.5%and1.0%calcium treatment is310.25U and301.82U, with no significant difference, but significantly increased than control (P<0.05).The potato with different concentrations calcium treatment its cell wall related physiological indexes changing situation after127days storage as:the cellulose content and protopectin content for tuber with1%calcium treatment is29.98%and5.51%similar to CK; and water-soluble pectin content is0.12%o, significantly lower than CK (P<0.01); The cellulose activity and pectinase activity is23.55U and15.40U slightly lower than CK.The potato with different treatment its membrane related physiological indexes changing situation after127days storage as:the average conductivity for tuber by postharvest soaking is lower with8.33%than the field spraying which not significant different with CK; the average MDA content for tuber by field spraying and postharvest soaking is0.28mmol/g-FW and0.25mmol/g-FW, with no significant difference but decreased than CK (P<0.05); The peroxidase activity for tuber by postharvest soaking is301.83U, higher than field spraying and CK.The potato with different treatment its cell wall related physiological indexes changing situation after127days storage as:the cellulose content for tuber by field spraying is32.43%higher than postharvest soaking treatment and CK, protopectin content is6.51%significant higher than postharvest soaking and CK (P<0.05), thereamong the cellulose content and protopectin content for tuber by postharvest soaking are slightly higher than CK; the water-soluble pectin content for tuber by postharvest soaking is lower than field spraying with0.04‰and lower than CK with0.06‰(P<0.01); the cellulose activity for tuber by postharvest soaking is lower than field spraying treatment with4.63U and lower than CK with12.48U, the pechtinase activity is lower than field spraying and CK with8.09U,5.81U (P<0.05) respectively.In the microstructure aspect, the cell wall average thickness for tuber by postharvest soaking is2.59um, with obviously thickening than control (P<0.01); the postharvest soaking can effectively promote the tubers synthesis of large and small starch grains, with37.38urn average particle size of the starch grain, the average starch grain for each cell is4.28pc with a slight increase than CK but the difference is not obvious.The potato by postharvest soaking treatment its tuber quality indicators changing situation after127days storage as:the dry matter content for tuber with1%calcium treatment is21.37%, and starch content is3.07%, protein content is5.32%, all higher than CK, the reducing sugar content is0.66%with significant reduce than0.5%calcium treatment (P<0.05) and highly significant reduction than CK (P<0.01); the tuber with0.5%and1.0%calcium treatment carry a similar amylase activity about0.18mg/g·min which lower than CK.Overall,1%calcium treatment can effectively improve the potato tubers storability during the storage period; the postharvest soaking is more effectively than field spraying calcium solution to stabilize the membrane function of potato tuber and dramatically inhibit the cell wall hydrolase activity, meanwhile to maintain the main component content of the cell wall and delay the tuber softening and senescence; the1%calcium treatment can effectively stabilize the potato tuber quality during the storage period.