Susceptibility to downy mildew (Plasmopara viticola) of different Vitis varieties

The susceptibility of different varieties of Vitis vinifera and other Vitis species to downy mildew (caused by Plasmopara viticola) in field, greenhouse and laboratory tests was compared over a period of three years. Different degrees of susceptibility were detected. The most susceptible V. vinifera varieties were ‘Treixadura’ and ‘Albariño; ‘Cabernet Sauvignon’, ‘Mencía’ and ‘Chasselas Doré’ were the least susceptible. The non-vinifera varieties showed no symptoms of downy mildew in the field. Surprisingly, in laboratory and greenhouse tests, the rootstock 110-R was much more susceptible to infection than S04. No relationship was seen between susceptibility and berry colour, or the time of sprouting or fruit ripening. Neither was any correlation seen between susceptibility and the condition of being a traditional or introduced variety. Better knowledge of the susceptibility to downy mildew of different varieties would allow for growers and breeders to select those that are more resistant.     

Sensitivity,resistance stability,and cross-resistance of Plasmopara viticola to four different fungicides

Baseline sensitivity to fungicides was determined in 105 Plasmopara viticola isolates using the floating leaf disk test. The mean EC₅₀ values were 0.372 ± 0.104, 0.604 ± 0.215, 0.306 ± 0.101, and 0.922 ± 0.209 μg mL⁻¹ for fluxapyroxad, benthiavalicarb-isopropyl, ametoctradin, and famoxadone, respectively, which we regarded as the baseline sensitivity to the four fungicides. Resistant mutants can be generated using a median effective concentration or a minimum inhibitory concentration to fluxapyroxad, benthiavalicarb-isopropyl, ametoctradin, and famoxadone respectively, but the resistance stability of resistant mutants from the minimum inhibitory concentration (MIC) was significantly lower than that from the median effective concentration (EC₅₀). In brief, high resistant mutants obtained was at the higher concentration, the resistance stability of the mutants recovered was more quickly. But lower resistant mutants obtained was at the lower concentration, the resistance stability of the mutants recovered was slower. Even if the resistance level of the mutants is low, it is more capable of stably heritable. These data indicate that the highest dosage is not used, resistance will still develop. In a correlation analysis, no cross-resistance to each other of these four fungicides was observed.     

抗青枯病花生资源的种子大小 及主要品质性状的遗传分化

以123份不同类型的抗青枯病花生种质为材料,对荚果大小、种子大小、出仁率、蛋白质、含油量和脂肪 酸等性状遗传分化进行了研究。研究结果表明,在我国抗青枯病花生资源中,高油酸种质资源较多,这些资源的荚 果及种仁大小,油酸、亚油酸、棕榈酸、硬脂酸、花生酸、花生烯酸、山嵛酸含量性状均存在丰富的遗传变异;但是,高 含油量资源较少,而且在含油量、蛋白质含量和出仁率方面的遗传多样性不丰富。根据12个与种子品质相关性状 信息, 123份抗青枯病资源被分成2组5亚组13个品种群,这些品种(群)与已被广为利用的骨干抗病亲本协抗青 和台山三粒肉之间存在很大的遗传分化。     

不同种茎处理对甘蔗品种萌芽幼苗期抗旱性的影响

在控制环境条件下研究了3种种茎处理方法对不同甘蔗品种品种萌芽出苗和幼苗生长的影响。在本试验的干旱条件下，F172的萌芽出苗几乎不受干旱影响。而其它3个品种则明显受干旱影响。对于广西主栽品种桂糖11号和新台糖16号，剥叶不砍种处理在干旱的条件下出苗和幼苗生长相对较好。     

大豆感染灰斑病菌后超氧化物歧化酶活性的变化

用人工接种的方法，分别将灰斑病菌接种在5个不同抗性的大豆叶片上，分析了接种后不同时期大豆叶片中超氧化物歧化酶(SOD)活性的变化规律。结果表明，生理小种和供试品种组合不同，SOD的活性变化规律不同；但总的趋势是随着接种后时间的推移，抗感品种的SOD活性的变化呈曲线上下波动，这种曲线体现了大豆感染灰斑病菌后SOD活性的动态变化规律。因此，认为接种灰斑病菌10个生理小种后大豆叶片中SOD活性的变化是大豆对灰斑病侵染后产生的一种普遍性反应，有利于提高大豆的抗病性；但不宜作为抗性鉴定的指标。