The effect of delays in establishment of a static or dynamic controlled atmosphere on the quality of ‘Hass’ avocado fruit

The effect of delays of 1, 5, 10 or 15 d after harvest in establishing a static controlled atmosphere (SCA) or dynamic controlled atmosphere (DCA) on the quality of ‘Hass’ avocados (Persea americana Mill.) was investigated. Fruit were stored at 5 °C in SCA (5% O₂/5% CO₂) or DCA (<3% O₂/0.5% CO₂) for 6 weeks and compared with fruit stored in air. In addition, to determine whether increasing the CO₂ in the DCA would affect the fruit quality, DCA-stored fruit were compared with fruit held in a DCA with 5% CO₂ (DCA + CO₂) established 1 d after harvest. The quality of fruit was assessed at the end of storage and after ripening at 20 °C. DCA-stored fruit ripened in 4.6 d compared with 7.2 d for SCA-stored fruit, or 4.8 d for air-stored fruit. In addition, the incidences of stem end rot (SER), body rot (BR) and vascular browning (VB) were lower in DCA-stored fruit (35%, 29% and 29%, respectively) than in SCA-stored fruit (57%, 52% and 49%, respectively), or air-stored fruit (76%, 88% and 95%, respectively). Delaying the establishment of both SCA and DCA for 15 d resulted in significantly more advanced skin colour at the end of storage (average rating score 11.9) compared with other delay periods (4.6–5.1). There was no significant effect of delay on the time to ripen, skin colour when ripe or any ripe fruit disorder incidence. The incidence of diffuse flesh discolouration (DFD) was not only <1% when averaged over all delays but only occurred at >0.5% incidence in the 15 d delay treatment in DCA (4.8%) and not in SCA. The incidence of diffuse flesh discolouration was 62% in air-stored fruit. Inclusion of 5% CO₂ in DCA retarded fruit ripening from 4.7 to 6.9 d and increased the incidence of rots at the end of storage from 5% to 14%, and increased the incidence in ripe fruit of SER from 30% to 56% and of BR from 27% to 55%. It is concluded that fruit quality was better after CA storage than after air storage, and that DCA storage was better than SCA. The effect of DCA is to independently reduce the time to ripen after storage and the incidence of rots when ripe. Delaying the application of SCA or DCA did not affect the expression of rots, but may increase the incidence of DFD. Inclusion of CO₂ at 5% in CA retarded fruit ripening but stimulated rot expression and should not be used for CA storage of New Zealand grown ‘Hass’ avocados.     

大豆抗腐霉根腐病的生理差异研究

腐霉根腐病是大豆主要的土传病害,为揭示抗感病大豆品种的生理差异,对不同抗性品种在腐霉病原菌侵染下的大豆下胚轴中丙二醛、苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、可溶性糖、脯氨酸含量的变化进行测定。结果表明:腐霉菌侵染后,抗病大豆品种下胚轴的丙二醛含量增加不十分明显;可溶性糖含量都是正向增加,苯丙氨酸解氨酶活性,过氧化物酶活性,脯氨酸含量在不同时段都有所增加且抗病品种明显高于感病品种。而感病品种在腐霉菌侵染条件下,大豆下胚轴中丙二醛含量累积较高,可溶性糖在某一时段内有所减少,苯丙氨酸解氨酶活性、过氧化物酶活性,脯氨酸含量增加幅度小于抗病品种,表明抗病品种具有较强的生理生化调节能力。     

玉米茎腐病生防菌株的筛选及抑菌作用研究

以吉林省玉米茎腐病优势菌株禾谷镰孢菌（Fusarium graminearum）为供试菌,从土壤中分离筛选生防菌株,获得对禾谷镰孢菌具有显著抑制作用的细菌菌株GsAl-2,抑菌率为46.27%。经分子生物学鉴定及系统发育分析,确定其为Asaia lannensis。通过抑菌机制研究表明,GsAl-2可显著抑制禾谷镰孢菌生长,使菌丝细胞膜渗透性增强、内含物外溢、菌丝脂质过氧化程度提高。GsAl-2与玉米膜下滴灌水肥药一体化技术联用试验表明,GsAl-2对玉米茎腐病的田间防效为58.68%±1.78%,GsAl-2的施用并未增加玉米表观病害。探讨A.lannensis的生防作用,为其在农业病害防治方面的应用提供基础信息。     

施用长效缓释尿素对大豆根腐病及产量的影响

为了探明长效缓释尿素是否对大豆根腐病病情指数有影响,其影响是否是导致产量降低的主要因素,试验于2014 年在大豆鼓粒期采用通径分析的方法对根部主要生理指标、大豆根腐病病情指数与产量之间的关系进行了通径分析。结果表明：施用长效缓释尿素的处理病情指数最低,达到33.96%,其产量最高为2998.65 kg/hm2。在对影响大豆产量的根部参数的通径分析中可以看出,直接通径系数最大的为地下鲜重的0.4649,说明其为最关键因子。根腐病病情指数也是影响大豆产量的因素之一,但其不是最主要的因素。长效缓释尿素主要是通过增加地下鲜重从而影响产量。     

甘薯抗茎线虫病种质资源的筛选与抗病性评价

对81份甘薯材料进行了茎线虫病、黑斑病和根腐病抗性鉴定和评价。结果表明:同时抗这3种病害的甘薯品种(系)较少,仅郑04-4-2和徐062826对甘薯茎线虫病抗侵入和抗扩展的同时,对黑斑病和根腐病也具有较高的抗性水平;另外有部分品种(系)如泰中7号、浙紫1号、徐060407等达到抗两病水平,可作为甘薯抗病育种的双抗亲本加以利用。     

3种液体地膜对大豆根腐病及产量的影响

为了找到一种能有效预防大豆中后期根腐病发生的并保证增产措施。本研究对3种液体地膜喷施下的根腐病发病率及产量进行了测定。结果表明液体地膜对大豆苗期镰孢菌根腐病,疫霉根腐病均有加重现象,但差异不显著。花期及后期对疫霉根腐病有防治效果,其中禾美特液体地膜对大豆疫霉根腐病防效最高,达21.83%。3种液体地膜对大豆均有增产作用,禾美特液体地膜处理增产效果最好,增产率达12.48% 。液体地膜能有效预防大豆花期及后期大豆疫霉根腐病,并有效提高大豆产量。禾美特液体地膜的抗病效果和增产效果最好。     

生姜腐烂病的发生及其防治研究

生姜腐烂病是江西省兴国县生姜生产发展中的主要病害.本文经田间调查及室内研究确定该病是由青枯假单胞杆菌(Pseudomonas solanacearum(Smith)Smith)侵染所致,并对病害的症状、病原的形态特征、发病条件和综合防治措施进行了探讨.     

宁夏地区玉米镰孢茎腐病病原菌的分离与鉴定

为明确宁夏地区玉米镰孢茎腐病病原菌的种类及优势病原菌,本研究于2020年采集宁夏地区玉米(Zea mays L.)茎腐病样品36份,对所采集样品进行组织学分离、纯化和单孢分离,参照Nelson等分类系统进行形态学鉴定,并结合镰孢菌特异性引物EF-1α进行序列分析.本研究共获得209株镰孢菌,包括禾谷镰孢复合种(Fusa...     

奶牛腐蹄病的病因及防制措施

通过对奶牛腐蹄病的病因、治疗、预防及控制等方面的综述,从日粮营养、环境卫生、饲养管理、遗传育种等诸多方面探讨,提出了实用有效的防制措施。     

8种农药对贡柑黑腐病菌丝生长和孢子萌发的影响

利用菌丝生长速率法及孢子萌发法测定了8种化学杀菌剂对贡柑黑腐病0hernaria cirri）的毒力。结果表明,用菌丝生长速率法测定时250g／L阿米西达效果较差,70％甲基托布津效果一般,其余6种农药均表现较好活性;用孢子萌发法测定时80％戊唑醇、40％腈菌唑效果较差,250g／L丙环唑、250g／L阿米西达表现一般,80％代森锰锌、10％苯醚甲环唑、70％甲基托布津、25％咪鲜胺均有较好的活性。