异源双根对连作障碍下咖啡幼苗氧化损伤的缓解效应

Mitigative Effect of Heterologous Double-root on Oxidative Damage of Coffee Seedlings under Continuous Cropping Obstacle

以中粒种咖啡‘热研1号’(Caffea canephora‘Reyan No.1’)和大粒种咖啡1号(Caffea liberica No.1)形成中粒种-大粒种异源双根咖啡和中粒种-中粒种同源双根咖啡,利用连作障碍咖啡园土壤开展幼苗培养试验,包括根际土培养异源双根咖啡(T1)和同源双根咖啡(T2),非根际土培养异源双根咖啡(T3)和同源双根咖啡(T4)。通过比较各处理植株过氧化氢(H_(2)O_(2))及丙二醛(MDA)含量、抗氧化酶活性及非酶抗氧化物含量,探讨异源双根对连作障碍下咖啡幼苗氧化损伤的缓解效应。结果表明:根际土培养后,T1较T2处理植株超氧化物歧化酶(SOD)、单脱氢抗坏血酸还原酶(MDHAR)等抗氧化酶活性显著提高,脱氢抗坏血酸(DHA)、氧化型谷胱甘肽(GSSG)等非酶抗氧化物含量显著下降,H_(2)O_(2)及MDA含量显著下降,连作障碍下异源双根咖啡较同源双根咖啡受氧化损伤影响小。T1、T3处理间或T2、T4处理间,植株叶片H_(2)O_(2)及MDA含量差异均不显著;且叶片氧化损伤评价指标与植株抗氧化系统指标的相关性较差,叶片对连作逆境较不敏感。根系H_(2)O_(2)含量在T1、T3处理间或T2、T4处理间差异显著,而MDA含量在T1、T3处理间差异不显著,在T2、T4处理间差异显著,连作逆境使植株根系产生较多活性氧;根系氧化损伤评价指标与根系DHA、还原型谷胱甘肽(GSH)、GSSG含量极显著正相关,与SOD、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、脱氢抗坏血酸还原酶(DHAR)、单脱氢抗坏血酸还原酶(MDHAR)活性极显著负相关,并且,与叶片DHA、GSH、GSSG含量及POD活性显著或极显著正相关,与SOD、GR、MDHAR、抗坏血酸氧化酶(AAO)、DHAR活性显著或极显著负相关,根系氧化损伤受根系及叶片抗氧化系统的共同影响。综上,连作障碍下,同源双根咖啡根系受氧化损伤大,异源双根咖啡通过根系及叶片抗氧化系统缓解根系氧化损伤。

The soil of the continuous cropping obstacle garden of coffee was used to cultivate Caffea canephora‘Reyan No.1’/C.liberica No.1 heterologous double-root grafting coffee seedlings and C.canephora‘Reyan No.1’homologous double-root grafting coffee seedlings.In order to study the mitigative effect of heterologous double-root on the oxidative damage of coffee seedlings under continuous cropping obstacle,the contents of H_(2)O_(2),MDA and non-enzyme antioxidant and antioxidant enzyme activity among heterologous double-root coffee in rhizosphere soil(T1),homologous double-root coffee in rhizosphere soil(T2),heterologous double-root coffee in non-rhizosphere soil(T3)and homologous double-root coffee in non-rhizosphere soil(T4)were observed.The results indicated that compared with T2,the activity of SOD and MDHAR was significantly increased,and the content of DHA,GSSG,H_(2)O_(2) and MDA was significantly decreased in T1.The oxidative damage of the heterologous double-root coffee was less than that of the homologous double-root coffee under the continuous cropping obstacle.There were no significant differences in H_(2)O_(2) and MDA content in the leaves between T1 and T3 or T2 and T4,and the correlation between the evaluation indexes of the leaf oxidative damage and the indexes of plant antioxidant system was poor.The leaves were less sensitive to continuous cropping stress.There was significant difference in H_(2)O_(2) content in roots between T1 and T3 or T2 and T4.There was no significant difference in MDA content between T1 and T3,but significant difference between T2 and T4.More root active oxygen species were produced under continuous cropping obstacle.The evaluation indexes of the root oxidative damage were very significant positively correlated with the content of DHA,GSH,GSSG,and very significant negatively correlated with the activity of SOD,POD,APX,GR,DHAR and MDHAR in roots.Also,the evaluation indexes of the root oxidative damage were significantly or very significantly positively correlated with the content of DHA,GSH,GSSG and the activity of POD,and significantly or very significantly negatively correlated with the activity of SOD,GR,MDHAR,AAO and DHAR in leaves.The root oxidative damage was affected by both the root and leaf antioxidant system.In summary,the roots of the homologous double-root coffee were more damaged by oxidation than those of the heterologous double-root coffee under the continuous cropping obstacle,and the root oxidative damage of the heterologous double-root coffee was alleviated by the root and leaf antioxidant system.