萝卜肉质根糠心的生理生化指标变化特征

Changes of Physiological and Biochemical Indexes of Hollowing Radish Fleshy Root

为探究不同种质萝卜肉质根在生长中后期不同糠心等级下的生理变化规律,为萝卜糠心调控的深入研究和耐糠心品种选育提供理论依据。该研究以耐糠心萝卜C70922、不耐糠心萝卜C3156、中等耐糠心萝卜C83471为材料,分别测定不同糠心等级下肉质根相关生理指标变化,并通过石蜡切片观察肉质根糠心过程中细胞变化规律。结果显示:(1)不同萝卜品种肉质根的超氧化物歧化酶(SOD)活性均在第1级糠心时达最高或最低,其过氧化物酶(POD)活性、游离脯氨酸含量均在第2级糠心时达到极值。(2)不同萝卜品种肉质根的可溶性糖和还原糖的含量均在第3级糠心时达到极值。(3)随着萝卜糠心等级提高,各萝卜品种肉质根的可溶性淀粉含量呈先减少后增加再减少的趋势。(4)耐糠心萝卜C70922肉质根的纤维素含量在不同糠心等级之间的变化不显著,而不耐糠心萝卜C3156与中等耐糠心萝卜C83471肉质根的纤维素含量均在糠心第3等级时达到最高。(5)肉质根维生素C的积累与萝卜糠心等级密切相关。(6)萝卜肉质根中心相同部位石蜡切片观察发现,相同糠心等级下随耐糠心性的减弱,细胞体积逐渐变大,排列更松散,细胞壁变溥;相同萝卜材料中随糠心等级增加,细胞破碎更多,溢缩程度加重,溢缩中心木质化程度提高,空洞更明显。研究表明,萝卜糠心过程中SOD、POD、游离脯氨酸、纤维素、维生素C以及细胞形态均会发生显著变化。

To explore the mechanisms of physiological change in radish fleshy roots at different hollowness levels during the middle and late growth periods,and to provide theoretical basis for the in-depth study of hollowness regulation and breeding,we used such three varieties as resistance hollowness variety C70922,not resistance hollowness variety C3156 and medium resistance hollowness variety C83471.Here,the changes of physiological and quality indexes were measured under different hollowness levels of roots,and the cell changes in roots were observed by paraffin section.The results were as follows:(1)the activity of superoxide dismutase(SOD)in different radish varieties reached the highest or lowest in the first grade of hollowness,while activity of peroxidase(POD)and free proline content were the peaks in the second grade hollowness.(2)The contents of soluble sugar and reducing sugar in fleshy roots of different radish varieties reached the maximum value in the third grade hollowness.(3)With the deepening of radish hollowness,soluble starch contents decreased first,then increased and then decreased.(4)The cellulose content in the radish C70922 did not change significantly among different hollow grades,while the cellulose in the radish C3156 and C84371 are reached the highest in the third grade hollowness.(5)Additionally,the accumulation of vitamin C in fleshy roots was closely related to the grade of radish hollow.(6)In the same hollowness grade of fleshy radish roots,as the tolerance of the variety weakened,the individual cells were gradually larger,the arrangement was looser,and the cell wall became thin.As the hollowness grade increased in the same material,more cells were broken and the degree of the cell constriction increased.Therefore,SOD,POD,free proline,cellulose and vitamin C,as well as cell morphology of radish cells changed significantly during the process of hollowing in roots of radish.