黄土高原区苜蓿与小麦轮作系统根部入侵真菌研究

以甘肃庆阳黄土高原地区草田轮作系统中苜蓿(Medzfago sativn)和小麦(Triticum aestivum)为研究材料，分别于2002年两种作物的拔节期(分枝期)、开花期、成熟期和幼苗期(第3茬分枝期)取样，分离、鉴定了根部入侵真菌，测定了分离所得根部入侵真菌对其寄主作物及另一种轮作作物的致病力。结果表明：在试验区内共分离到27种根部入侵真菌，包括自小麦根系分离到26种，苜蓿侧根分离到23种，其中22种为苜蓿和小麦共同的根部入侵真菌。两种作物根部入侵真菌区系中优势种明显不同，苜蓿根部最主要的5种入侵真菌按分离率的高低依次为尖镰孢(Fusarium oxysporum)17．0％、大孢肉座菌(Selinia sp．)15．4％、茎点霉(Phoma medicaginis)9．5％、腐皮镰孢(Fusarium solani)6．7％及柱孢(Cylindrocarpon destructans)6．6％；而小麦根部5种最主要的入侵真菌按分离率的高低依次为黑团孢(Periconia sp.)15．0％、丝葚霉(Papulaspora sp．)12．1％、多主枝孢(Cladosporium herbarum)5．4％、丝核菌(Rhizoctonia sp．)4．0％及尖镰孢3．9％；总的真菌分离率亦是苜蓿高于小麦。苜蓿与小麦的根段带菌率均有随生长季的延长而增高的特征。在试验条件下，参试的苜蓿、小麦根部入侵真菌对苜蓿和小麦均有一定的致病力，但对苜蓿种子和幼苗的致病力强于对小麦种子和幼苗的致病力。在轮作体系中，小麦田轮作苜蓿应注意防治根部入侵真菌的危害。

Root-invading fungi of lucerne and winter wheat in the rotation system on the Loess Plateau

A study was carried out on root-invading fungi of lucerne (Medicago sativa) and winter wheat(Triticum aestivum)under the forage legume-cereal rotation systems on the Loess Plateau of eastern Gansu province, China. Roots of wheat and lucerne were sampled at spring jointing (spring branching), flowering, maturity and seedling or regrowth stage in 2002. Fungi were isolated from lucerne rootlets and the wheat root system. Pathogenicity of these root-invading fungi to lucerne and wheat were determined in the...