加拿大农药经营与使用许可管理制度

本文介绍了加拿大农药经营与使用许可管理制度的有关情况。加拿大实行联邦和省级平行立法体系,由联邦和各省政府按照法律划定的职责权限共同行使农药管理职责。     

The effect of root and shoot pruning on early growth of hybrid poplars

Planting stock type and quality can have an important impact on early growth rates of plantations. The goal of this study was to evaluate early growth and root/shoot development of different planting materials in typical heavy clay soils of northwestern Quebec. Using one-year-old bareroot hybrid poplar dormant stock, four planting materials were compared: (1) regular bareroot stock, (2) rootstock (stem pruned before planting), (3) whips (roots pruned before planting), and (4) cuttings (30 cm stem sections taken from the basal portion of bareroot trees, i.e. roots and shoot pruned). Rooted stock types (bareroot and rootstock) produced, on average, 1.2 times larger trees than unrooted stock types (cuttings and whips). However, shoot-pruned stock types (rootstocks and cuttings) reached similar heights and basal diameters as unpruned stock types (bareroots and whips), during the first growing season. Shoot pruning reduced leaf carbon isotopic ratios, suggesting that unpruned stock types were water-stressed during the first growing season. The stress was most likely caused by early leaf development while root growth occurred later in the summer. We conclude that shoot pruning bareroot stock is a useful management option to reduce planting stress without compromising early growth rates of hybrid poplars.     

加拿大食品法典工作机制

国际食品法典委员会（CAC）标准已成为全球食品管理机构和国际食品贸易中的重要参考标准。加拿大一直参与国际食品法典标准的制定工作,其机构设置和工作机制相对成熟完善,深入研究加拿大食品法典工作对我国相关工作的开展具有指导和借鉴意义。文章系统评述了加拿大食品法典工作机构设置和工作机制,并对进一步加强我国食品法典工作提出了建议。     

加拿大现代农业技术推广的特点与启示

加拿大完善高效的农业科技推广体系,确保了科研成果及时应用于农业生产过程中.农业科技推广体系具有的机构多元、方式灵活、手段多样、队伍高效精干和农业生产者高素质等特点,这为我国改革和完善农业科技推广体系提供了依据.     

加拿大的林业职业协会及其对我国的启示

从20世纪40年代开始, 加拿大陆续建立了林业职业协会, 包括8个省级林业职业协会、加拿大林业职业协会联盟以及加拿大林业资格鉴定委员会。实践证明, 这些协会在保护公众利益和促进森林资源的可持续经营方面发挥了积极的作用。文中介绍了加拿大林业职业协会的管理, 并针对我国实际提出了建议。     

美国和加拿大的林业非政府组织建设

介绍了美国、加拿大4个重要林业非政府组织的概况、运作模式和管理制度, 对促进我国林业非政府组织的发展提出了建议。     

Case definition for clinical and subclinical bacterial kidney disease (BKD) in Atlantic Salmon (Salmo salar L.) in New Brunswick,Canada

Bacterial kidney disease (BKD) is considered an important cause of loss in salmon aquaculture in Atlantic Canada. Causative agent of BKD is the Gram‐positive bacteria Renibacterium salmoninarum. Infected salmon are often asymptomatic (subclinical infection), and the disease is considered chronic. One of the challenges in quantifying information from farm production and health records is the application of a standardized case definition. Case definitions for farm‐level and cage‐level clinical and subclinical BKD were developed using retrospective longitudinal data from aquaculture practices in New Brunswick, Canada, combining (i) industry records of weekly production data including mortalities, (ii) field observations for BKD using reports of veterinarians and/or fish health technicians, (iii) diagnostic submissions and test results and (iv) treatments used to control BKD. Case definitions were evaluated using veterinarians’ expert judgements as reference standard. Eighty‐nine and 66% of sites and fish groups, respectively, were associated with BKD at least once. For BKD present (subclinical or clinical), sensitivity and specificity of the case definition were 75–100% varying between event, fish group, site cycle and level (site pen). For clinical BKD, sensitivities were 29–64% and specificities 91–100%. Industry data can be used to develop sensitive case definitions.     

Forage production and quality of 4 perennial grasses grown under and outside canopies of matureProsopis glandulosa Torr. var.glandulosa (mesquite)

Comparisons were made of dry matter production and forage quality of two coolseason grasses, Canada wildrye (Elymus canadensis L.), Virginia wildrye (Elymus virginicus L.), and two warm-season grasses, green panic (Panicum maximum var.trichoglume Eyles) and plains bristlegrass (Setaria leucopila Scribn. & Merr.), planted under and outside the canopies of mature honey mesquite (Prosopis glandulosa Torr. var.glandulosa). Green panic gave the greatest cumulative dry matter yield in both canopy (5120 kg ha^–1) and open (3370 kg ha^–1) locations, followed by plains bristlegrass under mesquite (1130 kg ha^–1) and in the open (570 kg ha^–1). One-time yields from Canada wildrye and Virginia wildrye, under and outside mesquite canopy, were 247 and 329 kg ha^–1, and 272 and 268 kg ha^–1, respectively. Dry matter production of green panic (p=0.001) and plains bristlegrass (p=0.026) was greater under mesquite only for the first of four harvests, although both warm-season grasses exhibited a trend for greater production under mesquite than in the open. Average nitrogen content of green panic was greater (p=0.0004) under mesquite than in the open, while plains bristlegrass exhibited a trend for greater crude protein content in the open than under mesquite. Overall, moisture content of the warm-season grasses was greater (p=0.0001) under mesquite than in the open, while Virginia wildrye was more (p=0.002) succulent under mesquite than in the open. Averagein-vitro dry matter digestibility of warm-season grasses was almost significantly greater (p=0.0501) in the open than under mesquite. Canopy soils contained significantly more organic C (p=0.0004) and total N (p=0.0001) than open soils, with differences of 8.3 Mg organic C ha^–1 and 1.3 Mg total N ha^–1. Correlations indicated that soil fertility was more limiting to grass production than light intensity.