连作对花生光合特性和活性氧代谢的影响

Effect of Continuous Cropping on Photosynthesis and Metabolism of Reactive Oxygen in Peanut

大田和池栽试验结果表明,连作显著降低花生单叶光合速率(Pn)、群体光合强度(CAP)和叶面积系数(LAI),并随生育期的推进而降低更甚;LAI与CAP和作物生长速率(CGR)呈极显著正相关,Chl含量与Pn相关密切。LAI的降低是导致连作花生干物质积累少、荚果产量低的主要原因;不同品种类型对连作障碍的敏感性不同,鲁花12最敏感,而8130耐性最好。连作花生叶片的SOD、POD、CAT活性和可溶性蛋白质含量显著降低,MDA含量明显增加,且其变化随连作年限延长而加大;CGR与叶片中POD和SOD相关密切。植株中POD、SOD等叶片保护酶活性降低是导致花生生育不良和后期早衰的主要原因之一。

Continuous cropping is one of the main factors that affect the peanut yield. There are about 250 000 ha continuous cropping areas with a yield loss of about 110 000 t every year in Shandong province. Understanding the effect of continuous cropping on peanut photosynthesis and metabolism is very important to explore the yield-reducing reasons and relieve the loss of continuous cropping. In this study, photosynthetic performance of three peanut cultivars （8130, from Virginia; Luhua 12, from Spanish; Luhua 14, from interspecies crossing） was compared in field experiments with two farming patterns of continuous cropping（CP） and rotation cropping （RP） and the reactive oxygen metabolizing feature of plant under different cropping modes （One-year continuous cropping, T1; two-year continuous cropping, T2; rotation cropping, To ） was observed using pool test to understand the mechanism of CP press on growth and development of peanut. Results showed that CP press of peanut significantly decreased the rate of leaf net photosynthesis（ Pn ）and canopy apparent photosynthesis （CAP） , as well as leaf area index（LAI）, while little influenced chlorophyll （Chl） content. Significant positive correlations of LAI with CAP and with crop growth rate （CGR）, as well as Chl content with Pn were observed. Therefore, the decrease of LAI was the dominant factor that hampered dry mass accumulation and lowered pod production in CP peanut. Sensitivity of different peanut variety types to CP press was evident： Luhua12 〉 Luhua 4 〉 8130. The change of all the characters mentioned above became larger with the plant development. CP decreased the activities of SOD, POD, and CAT, and increased MDA content in leaf, and the changes were larger when the year of CP increased. CGR was significantly correlated with activities of POD and SOD in leaves and not correlated with MDA, CAT, and soluble protein. The activity decrease of protective enzyme, such as POD and SOD, was one of the main reasons for poor growth and development and early senescence in CP peanut.