对虾集约化养殖水环境中施用芽孢杆菌的营养条件研究

随着对虾集约化养殖的迅速发展,养殖环境遭到严熏的破坏,对虾病害频繁发生.人们在养殖生产中一般通过使用有益微生物制剂来改善养殖生态环境,抑制病原微生物,从而减少疾病的发生.微生物制剂在对虾集约化养殖过程中使用越来越普遍.微生物制剂的生物学作用是需要一定的营养条件,并达到一定的数量才能表现出益生作用.笔者以生产上常用的芽孢杆菌为例研究了其营养需求及水环境改善效果,以期为生产提供理论指导.     

1-MCP复合杀菌剂对西州蜜甜瓜常温贮藏品质的影响

为了探究不同保鲜剂复合杀菌剂对甜瓜的保鲜效果,以西州蜜甜瓜为试验材料,研究了抑霉唑硫酸盐、ClO₂、咪鲜胺、1-MCP、1-MCP复合抑霉唑硫酸盐和无菌水对甜瓜常温贮藏下品质的影响。结果表明,与对照无菌水相比,所有保鲜剂均可显著抑制甜瓜采后腐烂与失重,维持果实硬度和可溶性固形物含量,提升贮藏品质。1-MCP与1-MCP复合杀菌剂处理可显著抑制西州蜜果实的呼吸速率和乙烯释放速率,呼吸峰值较对照无菌水分别降低43.7%和37.5%,乙烯释放峰值较对照无菌水分别降低47.9%和53.7%,呼吸峰值和乙烯释放峰值出现时间均推迟3 d。其中1-MCP复合杀菌剂对果实可滴定酸和Vc含量保持效果显著,与对照无菌水相比,可滴定酸含量提高40.0%,Vc含量提高38.2%,对西州蜜甜瓜的保鲜效果最好。     

不同固定化微生物颗粒降解养殖尾水中污染物的性能评价

选取3种载体（凹凸棒土、卡拉胶以及硅藻土）进行固定化微生物颗粒制备,并对不同颗粒性能、污染物去除性能及主要影响因素进行了研究。颗粒性能研究表明：凹凸棒土与硅藻土固定化微生物颗粒具有较好的机械强度,卡拉胶机械强度低;在有营养补充的前提下,凹凸棒土和卡拉胶可以稳定释放1.50×106 CFU/mL和2.60×105 CFU/mL的微生物,硅藻土固定化微生物颗粒缓释性能较差;利用Monod方程拟合可得,对于CODMn,硅藻土固定化微生物颗粒具有最大的比降解速率（μmax）,卡拉胶与之相当,凹凸棒土最低,同时硅藻土固定化微生物颗粒的Ks值显著低于其他两种颗粒;同时,氨氮降解动力学也呈现了相似的规律。环境条件对固定化微生物颗粒降解污染物的影响分析表明：中性（pH=7）条件下,凹凸棒土、卡拉胶、硅藻土固定化颗粒降解CODMn的一级速率常数最高;凹凸棒土与硅藻土固定化微生物颗粒在中性和碱性条件下的降解氨氮速率更高,卡拉胶在中性条件下降解氨氮速率最高。固定化微生物颗粒降解CODMn、氨氮的一级反应速率常数随温度的升高而增大,其中凹凸棒土固定化微生物颗粒对温度的变化更为敏感。除了硅藻土固定化微生物 颗粒以外,随着污染物初始浓度的增加,其余两种降解CODMn的一级反应速率常数k1值显著上升（P＜0.05）。不同曝气强度下3种固定化微生物颗粒降解CODMn一级反应速率无显著性差异（P＞0.05）,更高的曝气强度对氨氮降解有利。     

Feeding behaviour as a limiting step in insecticide absorption for the wireworm Agriotes sp. (Coleoptera: Elateridae)

The fipronil control of wireworms field populations (larval Agriotes sp., Coleoptera: Elateridae) is difficult because of the low integumental penetration rates of this insecticide into the target larval body. The main way of insecticide absorption being associated with food, analysis of the larval feeding behaviour is of key importance for designing a strategy of dietary chemical control of those subterranean pests. In this purpose, a standard method for assessing the long-term survival of field specimens in the laboratory was developed together with experimental designs for investigating food searching and choosing by larvae. Larval biological performances under those laboratory conditions were checked monthly. Three criteria were taken into account for measures: the duration of individual survival, the gain in average body weight, and the moulting rhythm. Experimentation revealed that seed flour was highly desired by larvae and that larval feeding choice was affected over short distances only. This suggests the involvement of dietary preference rather than attractivity in the larval feeding behaviour. This implies that, at the operational step, insecticide had better be associated to food, either as a coating on the seeds, or inside preferred baits.     

论我国农业持续发展面临的挑战及对策

我国农业在改革开放以来经历了一段快速发展阶段。目前农业和农村的若干深层次的问题开始显露,并对农业的持续发展构成重大制约。本文具体分析了商品能源、矿产资源、水资源、土地环境、劳力、投资、农民收入以及价格等8个方面存在的问题。指出我国农业不能走常规高投入高产出的现代化路子,而应深入探讨带有中国特色的途径。     

秸秆的微贮及喂牛试验

为充分利用当地秸秆资料，１９９５～１９９６年作者在山西吕梁地区用微贮饲料（黄干玉米秸）饲喂６０头试验牛；对照组６０头牛所喂黄干玉米秸未作任何处理，育肥９０天。精料由玉米粉５６．１％、麸皮２１．４％、棉籽饼２０％、食盐０．５％、矿物质及其它添加剂０．３％组成，两组牛精料日喂量均按平均体重的１％分两次饲喂。试验结果表明：试验组日增重为０．８９３ｋｇ，对照组为０．６５ｋｇ，试验组增重提高７２．８％。两组牛的料重比分别为８．１６％和１０．４１％，即对照组比试验组多消耗精料２７．５７ｋｇ。试验组头均盈利１１７．１元，对照为１３．４元，试验组比对照牛多盈利１０．３７元。     

Are pre‐spraying growing conditions a major determinant of herbicide efficacy?

To evaluate the effect of pre‐spraying growing conditions on herbicide efficacy, two years of experimentation were conducted in which Persicaria maculosa plants were exposed to different light intensities for 1–4 days before metribuzin treatment. Specific leaf area, rather than plant growth rate or plant size, was the only parameter that correlated well with herbicide efficacy in both years of experimentation. The negative relationship between the ED₅₀ and the specific leaf area indicates that leaf characteristics might be an important determinant of herbicide efficacy, for instance through an effect on herbicide uptake. In the third year of experimentation this hypothesis was further investigated by raising six cohorts of weed plants at a 1‐week interval and thus exposing them to a range of weather conditions. Clear relationships between uptake and herbicide efficacy were found for a combination of four plant species (Solanum nigrum, Senecio vulgaris, Chenopodium album and Brassica napus) and two herbicides (phenmedipham and bentazone). For phenmedipham, uptake was negatively correlated with global radiation and positively correlated with relative humidity. For the herbicide bentazone the opposite was found. These results were not species‐specific. This study shows the importance of the sensitivity of herbicide × species combinations and indicates that pre‐spraying weather information is relevant for the development of reduced dose rate recommendations.     

PCR-based determination of colonization patterns during potato tuber infection by single and multiple pathogens

Potato tubers piled in storage are prone to infection by numerous pathogens. Each pathogen can cause damage alone, but severe losses often arise when more than one pathogen is involved. Currently, only a visual diagnosis is practiced on potato tubers before storing them, which does not allow any prediction of further disease spread. The aim of the present study was to determine differences in patterns of tissue colonization by several tuber decay pathogens and how late blight infection affects further tuber colonization by other important tuber pathogens. This study was conducted using artificial inoculation of potato tubers and PCR to provide an early and accurate diagnosis of disease development for major potato tuber rots, and to assess potential synergism/antagonism between Phytophthora infestans and other pathogens in stored tubers. In order to accurately follow the progress of each pathogen in tuber tissues, samples were collected over time from both the surface (peel, 0–2 mm depth) and internal tissues (flesh, depth > 2 mm) of the tubers at various distances from the inoculation site, at 3, 5, 7, 10, 12, 14, 17, and 19 days after inoculation. Successful detection of single or multiple pathogens was achieved using specific PCR-primers for each pathogen. Pathogens were always detected several centimeters ahead of the visible lesions. This tracking enabled us to determine the extent of colonization both on the tuber’s surface and in internal tissues by each tested pathogen, either after single or multiple infections involving P. infestans as the primary pathogen. The presence of P. infestans was shown to enhance the development of Pectobacterium atrosepticum and to slow down that of P. erythrospetica and Pythium ultimum. No noticeable effect on further tuber colonization by F. sambucinum, V. dahliae or V. albo-atrum was observed in the presence of P. infestans. This approach involving more than one pathogen is more realistic than classical studies considering single pathogens, and may be helpful in monitoring the sanitary status of stored tubers. Our results make the outcome of certain combinations of pathogens in potato tubers more predictable and may result in more efficient preventive measures.     

丽水绒盖牛肝菌的资源状况与生境条件

调查了绒盖牛肝菌在浙江丽水的分布情况,介绍了其形态特征和生境条件,并提出合理开发利用的建议。     

草酸处理对杧果贮藏效果的影响

 　杧果(Mangifera indica L. ) 栽培种‘红　6号’果实经采后草酸、采前草酸+采后草酸和采前钙+采后草酸处理后, 在常温(25℃) 和低温(14℃) 下贮藏, 结果发现3种处理有效缓解了果实硬度系数下降, 控制了果实病情发展, 对果实完全后熟时的可溶性固形物和可滴定酸含量没有产生明显的影响,草酸处理是　果采后贮藏保鲜可选择的方法。