不同埋藏方式及杀菌剂处理对黄土高原3种植物种子存活的影响

Effects of fungicide and sowing treatments on seed survival of three plant species on the Loess Plateau

为了探讨黄土高原典型草原植物病原真菌如何影响土壤种子存活,采用“种子袋埋藏与取回”的方法,对该地区3种常见植物胡枝子、长芒草和狗尾草种子进行杀菌剂处理、并且以不同方式(单种或者不同种混合)装入尼龙网袋后埋入土壤中,在田间分别埋藏1和3个月后取回种子袋,统计每袋种子的存活情况,并且进行萌发试验,检测种子生活力状况。结果表明:1)长芒草种子的田间发芽率最高,平均约为51.9%,显著高于胡枝子(14.6%)和狗尾草(26.1%)(P<0.05);随着埋藏时间的增加,3种植物种子发芽率显著增加;然而杀菌剂处理以及不同埋藏方式对种子发芽率没有显著影响。2)胡枝子种子的田间死亡率最低,平均约为1%,长芒草和狗尾草种子的田间死亡率分别为5.1%和4.4%;埋藏1个月后,杀菌剂未处理和单种埋藏条件下长芒草和狗尾草种子的田间死亡率分别为12.5%和11.0%,显著高于其他处理组合下两种植物种子的死亡率(P<0.05);胡枝子种子在埋藏1和3个月时,其种子死亡率在不同处理组合之间均无显著差异。3)长芒草种子的室内萌发率最高,平均约为64.3%,显著高于胡枝子(5.9%)和狗尾草(29.2%)(P<0.05)。随着埋藏时间的增加,胡枝子和狗尾草种子的室内萌发率显著下降,而长芒草种子的室内萌发率却显著增加。结果表明,病原真菌对土壤种子存活的影响因植物种而异;较单种埋藏相比,混合埋藏降低了种子的死亡率,可能是由于混合埋藏稀释了病原真菌的效应所致。

To explore how soil fungal pathogens influence seed survival in a typical grassland ecosystem on the Loess Plateau,we used a‘seed bag burial and retrieval’methodology,and treated seeds of three common plant species resident in the area(i.e.Lespedeza davurica,Stipa bungeana and Setaria viridis)with fungicide and then buried them in the field in seed bags,either with seeds of one plant species per bag or a mixture of the three species.We retrieved seed bags and evaluated seed survival in each bag after burial for 1 month and 3 months,and performed germination tests in the lab to determine seed viability.We found that,1)S.bungeana had the highest field germination percentage,51.9%on average,significantly higher(P<0.05)than that of L.davurica(14.6%)and S.viridis(26.1%).Seed germination percentage in the field of the three species increased significantly with increasing burial time,but it was not affected by fungicide treatment and sowing treatment.2)Seed mortality of L.davurica in the field was the lowest(about 1%on average),while field mortality of seeds of S.bungeana and S.viridis was 5.1%and 4.4%,respectively.In the non-fungicide and monoculture treatments,field mortality of seeds of S.bungeana and S.viridis in the field was 12.5%and 11.0%after 1-month burial,significantly higher(P<0.05)than that of other treatment combinations.Field mortality of seeds of L.davurica was not affected by fungicide treatment,sowing treatment or the length of burial time.3)Seed germination of S.bungeana in the lab test was the highest,64.3%on average,significantly higher(P<0.05)than that of L.davurica(5.9%)and S.viridis(29.2%).With the increase of burial time,seed germination percentage of L.davurica and S.viridis in the lab declined significantly,whereas germination of seeds of S.bungeana increased significantly.Our study suggests that the effects of fungal pathogens on seed survival varied among plant species,and seed mortality was decreased markedly in bags with a mixture of species compared to bags with a single seed species.