嵌紋病對玉米生育之影響及篩選抗病品系應用於田間之效益

Abstract

B型玉米矮化嵌紋病毒（MDMV-B）及A型、B型、D型、兩耳草（sourgrass）型及S－1分離株甘蔗嵌紋病毒（SCMV）都是玉米嵌紋病的病原，經以酵素連結抗體免疫分析（ELISA）從1983年至1988年調查之結果，以MDMV-B在田間發生的頻度最高；再經溫室苗期測定病原性及田間試驗評估各型病毒所造成的經濟為害度，亦以MDMV-B最為顯著。裂區設計的田間試驗比較MDMV-B接種與不接種的玉米之生育狀況，結果在預備試驗中統計分析病毒感染所造成的間接影響並不顯著，因此本研究的主要試驗都只比較病毒接種的直接效應。從1986年至1988年，三次田間試驗之結果，發現MDMV-B感染顯著影響玉米生長並造成嚴重減產，最高可達47.9％，一般推廣之飼料玉米減產22─29％，臺農1號減產則在20％以下，明顯異於感病品種之反應。從1983年至1989年共篩選2808個玉米品系僅11個呈抗病反應，172個呈中抗反應，324個呈中感反應，餘皆為感病反應者。選其中呈不感病反應的八個青割玉米品系進行田間試驗，其生長與產量較不受MDMV-B的影響，結果與惑病的對照有明顯差異。選育中的超甜玉米品系七個，經田間試驗證實MDMV-B惑染後，株高、莖軸、產量等均明顯受損，且品種間反應程度有差異。 B strain of maize dwarf mosaic virus (MDMV-B), strains A, B, D, and sourgrass of sugarcane mosaic virus (SCMV-A, -B, -D, -Sou), and undetermined isolate of SCMV (S-1) are all causal agents of corn mosaic in Taiwan. Investigating the occurrence of these viruses in 1983－1988 by ELISA, we found that MDMV-B was prevalent on corn producing areas of Taiwan. In the meanwhile MDMV-B is the main causal virus of corn mosaic was demonstrated by greenhouse seedling technique to determine the virulence of virus and field trials to estimate the yield losses of sweet corn inoculated with virus. Split-plot design was adopted for field experiments to evaluate the effects of MDMV-B on developments and yields of corn. The indirect effects of virus infection was not so significant that we only compared the difference between treatments of direct manual inoculation and noninoculation in the following experiments. Results of field trials in 1986－1988 showed that MDMV-B inoculation might severely reduce grain yield of inbred line “TA80-1410” up to 47.9%. Involved in this study two general released corn varieties (“Tainan 16” and “Tainung 351”) reduced 22－29% grain yields and “Tainung 1” usually lose less and never more than 20% of yield indicated that “Tainung 1” was significantly less affected by MDMV-B than other tested varieties. Screening corn lines for resistance to MDMV-B in 1983－1989, we found that in a total of 2808 tested lines, 11 lines were resistant, 172 lines were moderately resistant, 324 inles were moderately susceptible, and remainders were all susceptible to the virus. Eight selected lines, which originated from silage corn and were not susceptible to MDMV-B, were evaluated for the effectiveness of their resistances in the field. No significant effects of MDMV-B on developments and yields of tested lines were observed indicated that this level of resistance is effective to prevent yield losses to the disease in the field. Plant heights, stalk diameters, and ear yields of seven breeding lines of sweet corn were significantly reduced due to inoculation with MDMV-B in the experiment, and these disease responses of every corn lines were significantly different.