Use of netting and whitewash spray to protect papaya plants against Nivun Haamir (NH)-dieback disease

A disease causing the decline of papaya (Carica papaya) plants was noticed in the Jordan Valley in 1982. The disease caused severe yellowing of the upper leaves and dieback of the apex. The disease was not transmissible mechanically and continued efforts to associate viruses and viroids have so far been unsuccessful. Epidemiological observations suggested that the disease is airborne and probably caused by a mollicute. In order to test this hypothesis, plots were covered by an insect-proof net and with white nets providing 15, 30 and 50% shade. The 30%, 50% and insect-proof nettings provided complete protection, and the 15% netting reduced disease incidence to <2%, compared with>37% in the uncovered control plot. Spraying plants at weekly intervals with a commercial whitewash solution was also found to be effective in reducing disease incidence. The advantages of using a range of netting field treatments as a simple means for obtaining information on the epidemiological nature of a new disease are described.     

Rectangular Cover System of Manifold Method and Its Auto Mesh Algorithm

In contrast to the finite element method, another form of numerical method which is based on the using of rectangular math covers in manifold method is proposed. In this method, the element data is not a necessary in the input data files and it can be incorporated with the CAD technology conveniently. The theory and application of the method are discussed and the auto mesh algorithm of the cover system is also given in this paper. The numerical examples indicate that the method and the algorithm are accurate and effective.     

An Evaluation of Blueberry Cultivars Grown in Plastic Tunnels in Douglas County,Oregon

Abstract

Growing fruits and vegetables in plastic tunnels is known to accelerate maturity and protect quality. There are several studies on highbush blueberry (Vaccinium corymbosum) that demonstrate the ability of row covers to advance or delay crop maturity depending on how they are manipulated. Accelerating or delaying harvest time can prove to be very lucrative for producers. However, before producers start putting plastic tunnels over their crops it is important to know how blueberry cultivars will behave when grown under plastic. Six cultivars of southern highbush blueberry and eight cultivars of northern highbush blueberry were grown in a high hoop plastic tunnel for two seasons. Blueberry plants were grown under plastic from February 1 until their harvest was completed each year. After harvest, the plastic covering over the hoops was removed to help the blueberry plants develop fruit buds and meet winter chill requirements. On February 1 the plastic covering was returned to the high hoop tunnel after chilling requirements were met. As expected, fruit maturity dates were 1-3 weeks earlier for all the highbush blueberries grown inside the tunnel versus the same cultivars grown outside. The difference in maturity dates between cultivars grown under plastic and outside did change from one year to the next because of variation in the weather. Despite potential for poor pollination of blueberries in plastic tunnels, yields were significantly enhanced for four cultivars when grown under plastic tunnels. ‘Toro’, ‘Nui’, ‘Legacy’, and ‘Misty’ showed yield gains ranging from 1 to 4 times when grown under a plastic tunnel. Seed numbers per fruit were not significantly impacted by growing plants inside our tunnel.     

蕨类植物在园林绿化中的应用

蕨类植物种类丰富、适应性强、管理简便,非常适合园林应用。在简要分析我国蕨类植物种质资源的基础上,探讨蕨类植物在园林植物造景如庭院、地被、水景、岩石园等的应用,提出应在园林建设中重视蕨类植物,尤其是中国原产的蕨类植物和从国外引进的一些新优园艺蕨类品种,以丰富植物多样性和园林景观。     

Bearing properties of engineered wood products I: effects of dowel diameter and loading direction

The embedment tests of laminated veneer lumber (LVL) with two moduli of elasticity (MOE; 7.8 GPa and 9.8GPa), parallel strand lumber (PSL), and laminated strand lumber (LSL) were conducted in accordance with ASTM-D 5764. The load-embedment relation for each of these engineered wood products (EWPs) was established. The directional characteristics of bearing strength (_e), initial stiffness (k _e), and effective elastic foundation depth were obtained from the tested results. The effective elastic foundation depth (=E/k _e,E = MOE), based on the theory of a beam on elastic foundation, was obtained from thek _e and MOE. An of 90° (perpendicular to the grain) was calculated by dividingE ₉₀ [MOE of 90° from the compression test, but MOE of 0° (E ₀), parallel to the grain, obtained from the bending test] byk _e90, the initial stiffness of 90°. This study aimed to obtain the bearing characteristics of each EWP, taking into consideration their anisotropic structures, for estimating the fastening strength of a dowel-type fastener. The relations between the bearing coefficients ( _e,k _e,) on the loading direction and dowel diameter were established from the load-embedment curves. Based on the results of the embedment test, tested EWPs showed different tendencies in all directions from wood and glued laminated timber.Part of this study was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

中国干旱区积雪面积产品去云处理方法验证与评估

针对MODIS每日积雪产品中云覆盖现象严重这一问题,以中国干旱区作为研究对象,结合AMSR-E被动微波雪深数据,采用多时相、多传感器数据融合的方法进行去云处理,获取MODIS每日,4 d,8 d和MODIS与AMSR-E融合后的每日,4 d与8 d共6种新的积雪产品,并分别提取其积雪持续日数（SCD）。对比结果显示,MODIS与AMSR-E多传感器的阈值法4日融合产品在融合算法效率、云去除效果和融合后保持较高分类精度方面均有较好表现,其融合后的无云产品在全天气条件下具有96%的整体分类精度、80%的雪分类精度和99%的陆地分类精度,大大高于研究区原MODIS Terra-Aqua每日融合积雪产品全天候条件下64%,32%和70%的整体、雪、陆分类精度;并且由其提取的积雪持续日数不仅在最大程度上保持了原MODIS产品高的空间分辨率,而且精度较高,对研究区积雪的空间分布状况有很好反映。     

耐荫、半耐荫地被植物在广州公园中的应用

耐荫、半耐荫地被植物是营建复层植物景观的重要元素。在对广州公园进行调查研究基础上,文章归纳总结了耐荫、半耐荫地被植物的种类,并根据园林用途对其进行归类。共有34种,隶属25科33属。经分析,这些植物与其他园林要素之间常见的配置方式有路缘配置、与山石相配置等7种。     

Perennial ground cover plants as floral resources for urban pollinators: A case of Geranium species

Urban green areas, due to their high plant diversity, can be supportive as floral resources (nectar and/or pollen) to wild and managed pollinating insects. This research aims towards understanding the contribution of ornamental ground cover perennials as a food source for urban pollinators. We compare floral phenology and abundance, nectar and pollen production, and insect visitation to flowers of Geranium macrorrhizum, G. platypetalum and G. sanguineum, planted in the botanical garden of Lublin, SE Poland. The investigation revealed that the studied hardy geraniums exhibit many features valuable for pollinators, including large floral display (G. macrorrhizum and G. platypetalum), extended flowering period (G. sanguineum) and ample nectar and pollen reward (G. macrorrhizum). They can supply urban pollinators with a high quality food during spring and early summer time, i.e. the period of high food demand by many bee species. Moreover, hardy geraniums might be valuable plants for urban beekeeping as they are eagerly visited by honeybees. The investigated ground cover plants could therefore be considered in future city plantings.     

不同材料覆盖的土壤蒸发效果分析

为了有效控制草地退化,保护生物资源,保持"生态-经济-社会"的良性循环和生物资源的可持续利用.通过在希拉穆仁草原典型地带进行不同材料覆盖的土壤蒸发实验,并以恢复生态学为指导思想,研究了不同材料覆盖对土壤水分的影响.试验结果表明,干草、砾石覆盖均能有效地抑制土壤蒸发,相比对照而言,整个蒸发过程中,干草覆盖比砾石更能有效抑制土壤水分蒸发.     

信息化教学在基因工程药物课程中的运用

随着现代信息技术的发展,基因工程药物发展迅速。本人从玉林师范学院生物制药专业和本科生的实际情况出发,通过运用现代信息化技术和手段开展教学实践,取得了良好的教学效果。