小麦条锈病越夏过程的模拟研究

 以小麦条锈病大区流行模型PANCRIN为基础,按小麦成熟期和地理位置分区,加上有关越夏的各种参量,用于越夏过程的模拟。模拟试验结果确认和深化了如下认识:除周年麦外,任何单一成熟期的麦区都不能起越夏作用,必须生育末期植株和自生苗有交叠的双区组合才能实现越夏作用。春麦在越夏上直接作用不大;越夏作用大小主要取决于双区面积、成熟期交叠情况、当地流行速率和距承受其菌源的地区的远近。只要夏季最热一旬旬均温<22℃,上述交叠时期越早,越夏率就越高;完整的越夏过程包括菌源准备-越夏-后继增殖,陇东早播冬麦区的后继增殖对黄淮江汉冬麦发病可能有重要作用;越夏区停种的大区防治效果要受多种因素影响,欲获得良好效果,停种率要达95%以上。越夏区的分布和面积需要进一步查清,特别要注意允许条锈菌越夏的海拔下限是会随年份夏季气候变化而上下浮动的。在更全面地澄清了这些问题的基础上再设计和试行停种试验,是较为稳妥的。

Simulation study on oversummering process of wheat stripe rust caused by Puccinia striiformis West. in China

The oversummering process (OS)of Puccinia striiformis and wheat stripe rust was studied with the model PANCRIN. Simulations were conducted based on variation of wheat-growing periods in the corresponding geographic regions and the parameters relevant to OS. The results reconfirmed and intensified the existing knowledge about OS with the follo_wing points. Besides the year-round wheat-growing regions, OS could not be completed in any regions where the single-season wheat is grown. The OS could be completed only in the regions (RG)where the period of pre-harvest of wheat crop and the period of volunteer seedlings overlap. The OS was weak on spring wheat. The rate of OS was dependent upon the areas of RG, length of overlapping period in this region, infection rate, as well as the distance between the inoculum-source region and the target region. As long as the average temperature in the 10-days period during which the maximum temperature occurs in summer is <22℃, the earlier the overlapping-period occurs, the greater the OS rate is. Three steps may be involved in a completion of OS:inoculum accumulation-over summering-succeeding reproduction of the pathogen. The situation of succeeding reproduction of the pathogen in Longdong region, where the early-sowing winter wheat is grown, may have an important influence upon the OS in the target regions, where the sowing date is later than mid-October. Regional disease management with the no-wheat-planting strategy in the regions where OS occurs may be affected by many factors. To achieve a significant disease control, the area where the no-wheat-planting strategy is implemented should be equal to or greater than 95% of wheat-growing area. It is important to note that the low elevation limit for OS may float up or down depending on climatic variations in summers in two sequential years. Further investigation on geographic or regional distribution and the corresponding areas where OS possibly occurs prior to implementing the no-wheat-planting strategy for disease control in huge areas is recommended.