固定式太阳能喷灌系统喷洒水滴动能分布的研究

[目的]提高太阳能喷灌系统水力性能的稳定性和能量转换效率.[方法]采用激光雨滴谱仪测量技术,对225.7～1 145 W/m2之间不同光照强度下的固定式太阳能喷灌系统水力特性参数进行试验研究,分析了单个水滴动能、单位体积水滴动能及动能强度等参数的分布规律,并提出了系统能量转换效率的测量及计算方法.[结果]光照强度对单个...     

Process to extinction and genetic structure of a threatened Japanese conifer species, <Emphasis Type="Italic">Picea koyamae</Emphasis>

Since the end of the glacial age, Picea koyamae has been sparsely distributed in Japan as a relict species and is presently threatened with extinction. We investigated the population structure and genetic structure of nine populations of P. koyamae. Population size was assessed at 9–135 individuals in habitats ranging from 0.5 to 11.5 ha, and seedlings and saplings were observed in all but one particular population, which had a Sasa-type (bamboo grass) forest floor. The effective number of alleles per locus (N _e) within peripheral populations in the Yatsugatake Mountains was 1.8–2.7, much lower than that of core populations in the Akaishi Mountains (2.8–4.3) using five nuclear simple sequence repeat loci. This finding suggests that genetic variation in these populations has been reduced by isolation from other populations. The standardized genetic differentiation among populations (G′ _st ) was 0.410 and higher than that found in other Japanese conifers, suggesting that isolation and inbreeding have progressed in this species. In two isolated populations at the Yatsugatake Mountains, the fixation index (F _is ) was 0.315–0.354, much higher than the values determined for the other populations (−0.188 to 0.263). This suggests that these two populations have survived several generations while increasing the degree of inbreeding. However, the highest seedling density was in a population with low genetic variation and high F _is . The most serious problems at present appear to be the declining number of mature trees and the deterioration of suitable environments for seedling establishment.     

Certification of agroforestry tree germplasm in Southern Africa: opportunities and challenges

The lack of high quality agroforestry tree germplasm has long been recognized as one of the major challenges to widespread adoption of agroforestry in Southern Africa. Productivity levels realized in operational scale plantings are far less than those demonstrated in research and this has been partly blamed on the use of germplasm of unknown quality and low productivity potential. The lack of high quality germplasm is attributable to the absence of regulations to govern its production in the countries promoting agroforestry. Most of the agroforestry tree germplasm is sold or distributed without regard to its genetic, physiological and physical quality. Given these challenges, in this paper, we reviewed crop seed certification in general and tree germplasm certification in the USA, Europe, India, Southern Africa and the Organisation for Economic Cooperation and Development (OECD) with a view to find potential similarities with agroforestry tree germplasm. Only three countries in sub-Saharan Africa (Burkina Faso, Madagascar and Rwanda) were found to have tree germplasm certification: the OECD Forest Seed and Plant certification scheme. From the review, it is possible to establish agroforestry tree germplasm quality control systems, more so in countries that already have tree seed centres and tree seed regulations. A simple agroforestry tree germplasm certification scheme, based on the FAOs Quality Declared Seed (QDS) with truth-in-labelling is recommended. Three germplasm categories (audit, select and genetically improved) are recommended as a start. Furthermore, countries will need to develop new or amend existing agricultural seed policies and regulations to include agroforestry tree germplasm certification under QDS. Finally, germplasm quality standards for the selected agroforestry trees species in the respective countries will need to be developed.     

Nitrogen budgeting and quality of exponentially fertilized <Emphasis Type="Italic">Quercus robur</Emphasis> seedlings in Ireland

Current policy in Ireland calls for increased quality and quantity of broadleaved seedling plantings. Simultaneously, concerns regarding environmental contamination necessitate development of nursery production methods that minimize impacts. Exponential (E) fertilization has potential for producing high-quality seedlings through nutrient loading, while simultaneously minimizing nitrogen (N) losses during culture. We investigated the effects of a wide range (0.10–1.0 g N seedling⁻¹ year⁻¹) of E fertilization rates on seedling morphology and nutrition of Quercus robur L., as well as soil N status and N budget during one growing season in a bareroot nursery in County Carlow, Ireland. The N budget showed significant N losses, especially in the highest fertilizer treatments, due to high precipitation. Seedlings receiving the 0.5 E rate were morphologically and nutritionally superior to all other treatments. Results indicate that it may be possible to produce 1-0 bareroot seedlings meeting target specifications in Ireland and other countries of similar climate and soils if further manipulations to seedling culture are implemented; however, potential environmental degradation via N leaching must be considered when N loading in wet years.     

Effect of organic fertilizer on the growth and fruit yield of six paprika (<Emphasis Type="Italic">Capsicum annum</Emphasis> L.<Emphasis Type="Italic">)</Emphasis> cultivars in Malawi

The production of paprika (Capsicum annum L.) under small-scale farm conditions in southern Africa is constrained by low soil fertility and lack of appropriate cultivars. The objective of this study was to determine the growth responses and fruit yields of six cultivars of paprika to organic and inorganic nutrient sources. The study was conducted in 2007 and 2008 at Chitedze Agricultural Research Station in Malawi. A combination of six paprika cultivars and four nutrient sources, namely (1) organic input from Gliricidia, (Gliricidia sepium) biomass, (2) inorganic fertilizer, (3) integrated nutrient input (Gliricidia biomass + inorganic fertilizer), and (4) control (no nutrient input) were compared. Each combination was replicated five times. A split-plot design was used where nutrient sources formed the main plot and cultivars the sub-plots. Plant height differed due to nutrient source in 2007 and 2008, while differences due to cultivar were minor. The control plots produced the shortest plants (height < 50 cm), while plots receiving the integrated nutrient input produced the tallest plants (height > 60 cm). Numbers of branches and fruits per plant differed due to nutrient source and cultivar during most of the study period. Plants receiving either organic inputs (Gliricidia biomass) alone or the integrated nutrient input alone had significantly higher stem, leaf and fruit weight compared with the control. Average fruit yield was lower in control plots than in plots receiving the organic input alone or the integrated nutrient input. Among cultivars, Papri-King, Papri-Supreme and Papri-Queen produced higher dry fruit yield. The ASTA and RAL colour rating was within the internationally accepted range for fruit from the treatments.     

North American P type of Heterobasidion annosum shows pathogenicity towards Pinus halepensis in Italy

During a survey on the distribution of Heterobasidion root rot, the North American P group of H. annosum was recorded causing root rot on Aleppo pine, Pinus halepensis, in the gardens of a historical villa in Rome. This is the first report of Heterobasidion root rot on P. halepensis in its natural distribution area, the Mediterranean Basin.     

Extent,pattern, and multifunctionality of treed habitats on farms in Vermont,USA

Agroecosystems can serve as multifunctional landscapes when treed habitats such as woodlots, hedgerows, riparian buffers, windbreaks, and orchards, are conserved on farms. We investigated the extent, pattern, and multifunctionality of on-farm treed habitats for 16 Vermont farms in the Lamoille watershed of the Lake Champlain Basin. The site was selected because the land use pattern is representative of the region, containing a mixture of agriculture and forest in different habitat types. We used a GIS-based approach to delineate treed habitats on farms and conducted semi-structured interviews with farmers to explore their perception of the functions of treed habitats. Through an evaluation of the relationship between farm characteristics and spatial attributes of treed habitats, we found farm size to be an important variable. Larger farms had more land in treed habitats, while the pattern of these habitats was more complex on smaller farms. Average elevation of the farm, an indicator of biophysical conditions, was a stronger predictor of the extent of treed habitats than farm characteristics. From interviews, we found that farmers benefited from alternative forest products, both for direct consumption and sale, including firewood, timber, maple sugar, edible fruits and nuts, and wood crafts. Most farmers also recognized cultural and ecological functions provided by treed habitats. These results have implications for developing policies to promote the conservation of treed habitats, considering the preferences of the landowner or farmer.     

桦褐孔菌资源分布及其地域环境条件分析

对桦褐孔菌的资源分布及其环境条件进行了综述。濒危资源桦褐孔菌在我国主要分布在东北地区的大兴安岭、小兴安岭和长白山,在华北、西北和华南地区也有记录,并对其生存环境条件进行了汇总分析;另外,在山西的吕梁山中段和南段区域也发现了桦褐孔菌,并分析其形态特征、环境条件、品质等,可补充我国桦褐孔菌资源库,希望对桦褐孔菌的资源调查利用与资源保护提供更多的依据。     

Difficulties of wooden housing production sector in Brazil

ABSTRACT

This research identified the central hindrances found in Brazilian wooden housing scenario in the fields of finished product, producer, and sector. Thus, a questionnaire with three qualitative questions based on multiple-choice answers allowed investigating the difficulties faced by these producers in Brazil. This sector still faces obstacles in the three observed fields, especially for the negative aspects of house financing, housing technique certification, skilled hand labour, general costs incurred in local production, tax exemptions, public policies, utilization of wooden houses in public works, and other factors. These obstacles in wooden housing sector have created limitations of production potential and restrictions of its market. A current panorama from these obstacles was formed, which could contribute with sectoral development. Actions such as creation and institution of incentives and specific policies should consolidate as the main direction to reduce these difficulties faced by the wooden housing producers.     

冷害环境下遮阴处理对大果榛子萌芽生长的影响

为给大果榛子的规模引种提供参考,以‘龙榛’品种为材料,就叶芽和花芽萌动期其在冷害和不同光照强度条件下的生长状态进行分析。结果表明:枝条直径生长量方面,遮阴处理的平均值为5.26mm,未遮阴处理的平均值为7.91mm,未遮阴处理的大果榛子枝条直径与遮阴处理的存在极显著差异;芽长宽比方面,遮阴处理的平均值为1.61,未遮阴处理的平均值为1.49,2个处理间差异不显著。在遮阴处理下,大果榛子的营养生长(茎粗和叶芽大小)和生殖生长(花芽的萌发)均受到抑制,全光照条件下生长正常。冷害(≥2℃)并未对大果榛子萌发的叶芽和花芽造成低温伤害,光照强度对大果榛子生长影响显著。