32份木薯种质对疫霉根腐病的抗性评价和农艺性状分析

通过田间自然发病和室内离体接种方法对32份木薯种质进行了棕榈疫霉根腐病抗病性评价,结果表明,供试的32份木薯种质中,高抗种质7份,抗病种质7份,中感种质8份,感病种质7份,高感种质3份。其中高抗种质为‘H360’、‘华南11号’、‘华南8号’、‘H588’、‘桂热3号’、‘H873’和‘H971’;抗病种质为:‘F556’、‘H502’、‘GR911’、‘C-4’、‘F10’、‘南植188’和‘H47’。对其中14份抗棕榈疫霉根腐病木薯种质的农艺性状进行了鉴定和评价,结果表明‘华南8号’、‘GR911’、‘F556’、‘C-4’、‘H360’可以进一步加以利用。

Comprehensive assessment of 32 cassava germplasms for resistance to root rot disease (Phytophthora palmivora) and agronomic traits

130 Botryosphaeria dothidea isolates were collected from major apple-produced regions to assess the sus-ceptibility to tebuconazole by mycelium growth rate method and to test the virulence of resistance mutants.Resist-ant mutants were obtained by chemical screening and UV irradiation in the laboratory,and the fitness parameters of resistant and susceptible isolates were measured.The results showed that the EC50 values of 130 isolates varied from 0.051 6-1.925 4 μg/mL with the mean of (0.799 6±0.039 1)μg/mL and low resistant subcolony has been discovered.The resistant ratio of tested isolates was 71.54% and high-resistant strains has not discovered in major apple-produced regions.The resistance level of three resistant mutants was high with the resistant ratio of 58.82, 41.60 and 38.19 times,respectively.The fitness and virulence of resistant mutants had no significant difference between resistant and susceptible isolates.The resistance ratio of mutants decreased gradually after 9 generations of subcultures in the absence of fungicides and the resistance could not inherit stably.The results indicated that the resistance of B .dothidea to tebuconazole could gradually decline when the field selection pressure became lower.