Mehry Askary, Akbar Mostajeran, Giti Emtiazi
Department of Biology, University of Arak, Arak, Iran.
Pak J Biol Sci. 2008 Jun 15;11(12):1541-50. doi: 10.3923/pjbs.2008.1541.1550.
The potential enhancement of root colonization and nitrogenase activity of wheat cultivars (Baccross and Mahdavi) was studied with application of two Azospirillum brasilense strains (native and Sp7) co-inoculated with two Rhizobium meliloti strains (native and DSMZ 30135). The results indicated that the colonization was different due to the strains and cultivars of wheat were used. Native A. brasilense colonized wheat root better than Sp7 strain. However, Baccross cv. reacted better with native Azospirillum compared to Mahdavi cv. which reacted better with Sp7. When plants inoculated with dual inoculants (SP7 with standard Rhizobium), the colonization of Azospirillum were increased significantly (from 1.67 x 10(5) to 22 x 10(5) cfu g(-1) FW for Baccras cv. and 3.67 x 10(5) to 26 x 10(5) cfu g(-1) FW for Mahdavi cultivar). When the standard Rhizobium as co-inoculants changed to the native Rhizobium, the colonization of Azospirillum was higher when compared to the single inoculants but was almost the same when compared to the standard Rhizobium. When the standard or native strains of Rhizobium used as single inoculation of wheat roots, the number of Rhizobium in the wheat roots were not changed significantly. However, when plants co-inoculated with Rhizobium and Azospirillum, the colonization of Rhizobium was increased. Co-inoculation of standard strain of R. melilot with A. brasilense Sp7 showed that the colonization of Rhizobium were increased from 0.67 x 10(5) to 21 x 10(5) cfu g(-1) FW for Baccross cv. and 0.33 x 10(5) to 18 x 10(5) cfu g(-1) FW for Mahdavi cv. This behavior was the same when inoculation of Rhizobium was happened with the native one. In dual inoculation, the highest nitrogenase activity was measured in combination of the local strains (native A. brasilense with the native R. meliloti) and the lower one belongs to the combination of standard strains (Sp7 with standard R. meliloti). The difference in nirtogenase activity for different cultivars of wheat with Sp7 and standard Rhizobium is not significant but the difference for Sp7 strain plus native Rhizobium is significant (p > 0.05). However, the differences were not significant (p < 0.05) for nitrogenase activity in bacterial tubes, the difference for nitrogenase activity of co-inoculated plants with combination of Sp7 and Rhizobium either standard or native were significantly different.
研究了两种巴西固氮螺菌菌株（本地菌株和Sp7）与两种苜蓿根瘤菌菌株（本地菌株和DSMZ 30135）共同接种对小麦品种（Baccross和Mahdavi）根定殖及固氮酶活性的潜在增强作用。结果表明，由于使用的小麦菌株和品种不同，定殖情况存在差异。本地巴西固氮螺菌在小麦根上的定殖情况优于Sp7菌株。然而，Baccross品种与本地固氮螺菌反应更好，而Mahdavi品种与Sp7反应更好。当植株接种双重接种剂（Sp7与标准根瘤菌）时，巴西固氮螺菌的定殖显著增加（Baccras品种从1.67×10⁵cfu g⁻¹FW增加到22×10⁵cfu g⁻¹FW，Mahdavi品种从3.67×10⁵cfu g⁻¹FW增加到26×10⁵cfu g⁻¹FW）。当作为共同接种剂的标准根瘤菌换成本地根瘤菌时，巴西固氮螺菌的定殖与单一接种剂相比更高，但与标准根瘤菌相比几乎相同。当根瘤菌的标准或本地菌株单独接种小麦根时，小麦根中根瘤菌的数量没有显著变化。然而，当植株同时接种根瘤菌和巴西固氮螺菌时，根瘤菌的定殖增加。苜蓿根瘤菌标准菌株与巴西固氮螺菌Sp7共同接种表明，Baccross品种根瘤菌的定殖从0.67×10⁵cfu g⁻¹FW增加到21×10⁵cfu g⁻¹FW，Mahdavi品种从0.33×10⁵cfu g⁻¹FW增加到18×10⁵cfu g⁻¹FW。用本地根瘤菌接种时也是如此。在双重接种中，本地菌株组合（本地巴西固氮螺菌与本地苜蓿根瘤菌）测得的固氮酶活性最高，而标准菌株组合（Sp7与标准苜蓿根瘤菌）的固氮酶活性较低。不同小麦品种与Sp7和标准根瘤菌组合的固氮酶活性差异不显著，但Sp7菌株加本地根瘤菌组合的差异显著（p＞0.05）。然而，在细菌管中固氮酶活性差异不显著（p＜0.05），Sp7与标准或本地根瘤菌组合共同接种植株的固氮酶活性差异显著。
