The effect of understory removal on microclimate and soil properties in two subtropical lumber plantations

Understory vegetation is an important component in forest ecosystems. However, the effects of understory on soil properties in subtropical forests are not fully understood. We thus conducted an experimental manipulative study in two young fast-growing plantations—Eucalyptus urophylla and Acacia crassicarpa—in southern China, by removing understory vegetation in both plantations, to estimate the effects of understory vegetation on microclimate, soil properties and N mineralization. Our data showed that, after 6 months, understory removal (UR) in both plantations had greatly increased soil surface luminous intensity (90–500 cd) and temperature (0.5–0.8 °C); soil moisture was reduced in the Eucalyptus plantation but not in the Acacia plantation. Understory removal also reduced soil organic matter (SOM), but had little impact on other soil chemical properties, including total phosphorus, C/N, pH, exchangeable cations (K, Ca, Mg), available P, ande extractable NH₄–N and NO₃–N. We found a significant decline of soil N mineralization and nitrification rates in the 0–5 cm soils of UR in both plantations. The decline of SOM in UR may contribute to the lower N transformations rates. This study indicates that a better understanding of understory vegetation effects on soil N cycling would be beneficial to forest management decisions and could provide a critical foundation for advancing management practices.     

东南沿海防护林主要病虫害发生现状与防治策略

基于现有文献以及笔者多年来对沿海防护林病虫害的研究积累,对东南沿海防护林的主要树种木麻黄、红树林的主要病虫害发生和防治现状进行了综述,并提出了防治策略。     

Comparation on UV curing reactivity of Allyl abietate and allyl isopimarate北大核心CSCD

The UV curing reaction of the difference between allyl abietate(AA) and allyl isopimarate(AI) was studied. The conversion rate of the vinyl double bond was characterized and detected by FT-IR analysis. Results showed that conversion of double bonds are firstly increased then decreased with the increases of the dosage of initiators. Conversion of double bonds firstly increased and then leveling off with the increases of the illumination time, and AA is higher before the 200 s. AA is higher then AI under the same illumination intensity. Surface drying time of AA is shorter than AI, and relative curing speed become faster at the same conditions. Under the conditions of 2-hydroxy-2-methylpropiophenone(Darocure-1173)as photo initiator and dosage 6%, illumination time 200 s, illumination distance 4.5 cm and illumination intensity 100%, number average molecular weight of cure products of AA and AI are 4 176 and 9 407 with polymerisation degrees of 12 and 28, respectively. The obtained UV cured coating all have smooth and transparent appearance. It represented some superior properties in flexibility, mechanical impact strength, adhesive power, hardness, acid resistance, alkali resistance, salt resistance, water resistance, etc.. The hardness of AA and AI cured products are H and HB, respectively.     

Genetic diversity of Cucurbita maxima assessed using morphological characteristics and random-amplified polymorphic DNA markers in China

Cucurbita maxima is one of the most widely cultivated Cucurbitaceae in Heilongjiang province, China. The objectives of this study were to clarify the genetic diversity of 44 accessions from different geographical origins using morphological and molecular characteristics and to compare the consistency of these morphological and molecular characteristics. Morphological characteristics showed a large qualitative variability primarily according to fruit-related traits. Twenty-eight random-amplified polymorphic DNA (RAPD) markers produced 128 bands. Both morphological characteristics and RAPD markers grouped 44 accessions of C. maxima into four clusters, and the similarity coefficients ranged from 0.70 to 0.91 and from 0.40 to 0.98, respectively. DNA polymorphisms were highly consistent with phenotypic traits on rootstock C. maxima. The relationships between C. maxima from different origins were not clearly defined via morphological characteristics and RAPD analysis, suggesting some traits of C. maxima were specific to geographical location had disappeared or were weak in Heilongjiang province, which would not facilitate pumpkin breeding. Hybrid generations and their parent plants or sister lines were grouped into sub-clusters and showed little genetic distance according to both evaluation methods. Overall, morphological characteristics and RAPD markers were consistent and revealed high genetic diversity between C. maxima landraces from different origins.     

种子发芽纸测试报告

发芽纸是种子发芽试验必需的材料。国内首次研制成的专用种子发芽纸具有吸水快、持水性好、韧度大、厚度适中等特点。该纸无毒性、幼根不易穿透,且成本低。它既可衬垫于发芽容器中,更宜作发芽纸卷。试用结果表明,它能广泛适用于农作物、蔬菜、牧草、瓜、豆类等各种种子的发芽试验。在植物种子科学研究和生产实际中,经常需要进行种子发芽试验,一般的种子发芽试验常采用纸张作为发芽床。为使种子正常发芽和便于检查发芽结果,要求发芽纸有良好的理化特性。对此,国际种子检验协会对种子发芽纸的质地、灰分、韧度和吸水性能等有明确的规定指标,如要求纸张有足够强度,在发芽试验操作中不致撕破;质地要通透多孔,但幼根不能穿入纸中。国外已有不少国家都生产有专用的种子发芽纸,而国内至今还没有一种专门供种子发芽用的纸张,长期以来使用的是普通滤纸、卫生纸、乃至黄草纸等代用品。这些纸张在协调种子发芽所需的水气条件方面存有不少缺陷,其质地、强度或吸水性等都达不到要求。为了填补国内这一空白,浙江农业大学种子科学中心和浙江民丰造纸厂造纸研究所自1987年开始进行种子发芽纸的研制。经过多次反复研制和测试,已研制成功一种种子发芽纸。它厚度适中,既可平垫于玻皿之中,又可用作发芽纸卷,且成本低于目前代用的普通滤纸。经数家种子部门试用,反应良好。此将发芽纸研制过程中生物学适用性测试的部分内容报告如下。     

基于Web-GIS技术建立交通信息公共服务网站

在分析交通信息公共服务网站建立的意义和作用的基础上,设计了网站的结构与总体框架,提供了相关的空间数据与属性数据的采集与存储方式,并分析与建立了相关的Web-GIS结构,同时提出了在SuperMap平台与VS.NET开发环境中此类网站开发与实施方法。     

解钾细菌与黏土矿物协同促进玉米生长提高土壤养分有效性

为了揭示解钾细菌在西北矿区浅埋古河道土壤中对植物生长和土壤养分利用的影响,通过日光温室短期盆栽的方式,以不同黏土矿物配比的人工培土为基质模拟古河道不同质地土壤,以西北地区常见农作物玉米为宿主,研究解钾细菌在人工培土基质中的微生物数量变化规律,以及二者协同作用对玉米生长和矿质养分吸收的影响。结果表明:1)土壤黏土矿物含量增大有利于提高土壤解钾细菌数量,促进微生物活性。当黏土矿物质量分数为68%,速效钾质量分数约170 mg/kg时,解钾细菌数量最大;2)玉米地上部分干质量、根冠比、根系活力随黏土矿物含量增大而增大,以解钾细菌作用下黏土矿物质量分数68%的玉米生长效果最佳;3)在解钾细菌作用下,植物氮磷钾积累量和土壤养分利用的最佳土壤黏土矿物质量分数为45%、68%和75%,土壤钾素、氮素和磷素最大利用率分别达到65%、53%和17%;4)解钾细菌在土壤钾素含量低时促进土壤磷素吸收,土壤钾素过量时,促进土壤氮磷钾的吸收,提高土壤养分利用率。因此,土壤黏土矿物与解钾细菌相互作用,而且积极影响植物生长和土壤养分的吸收利用,这对进一步探寻适合矿区浅埋古河道土壤的微生物复垦技术,深入改良和开发矿区退化土壤具有重要意义。     

甘薯糠腐茎线虫病组织病理学扫描电镜研究

利用扫描电子显微镜对被甘薯糠腐茎线虫（ＤｉｔｙｌｅｎｃｈｕｓｄｅｓｔｒｕｃｔｏｒＴｈｏｒｎｅ）侵染的甘薯组织细胞的损伤情况进行了观察,结果表明：与健康甘薯相比,轻一中度侵染的病薯细胞失水,雏缩,细胞间隙加大,淀粉粒颗粒变小,大部分细胞出现及变形等病理变化,同时可见许多正在侵染的线虫;患病严重的薯块内细胞严重失水,皱缩,细胞间呈现大的空隙,维管组织变形,有的破碎,细胞内淀粉数量明业减少甚至完全丢失,     

Molecular and phenotypic characterization of Chinese wheat (Triticum aestivum) cultivars for resistance to Fusarium head blight

To identify excellent cultivars resistant to Fusarium head blight (FHB), 104 wheat cultivars were tested by single-flower inoculation using two prevalent pathogens from 2018 to 2020. Agronomic traits were also investigated. Six FHB-resistance quantitative trait loci (QTL), Fhb1, Fhb2, Fhb4, Fhb5, Fhb7 and Qfhb.crc-2D, have been assessed using previously reported DNA markers. A diagnostic marker has been used for Fhb1, and indicative markers linked to the other QTL were used. Results showed that (i) 12 (11.5%) cultivars were resistant to two pathogens in 3 years; among them, ‘Shengxuan 6’, ‘Wanhongbian 759’, ‘Yunong 903’ and ‘Yunong 901’ had good agronomic traits. (ii) Among cultivars with one resistance QTL, the severities of cultivars carrying Fhb1 and Qfhb.crc-2D were 2.2 and 2.8, respectively, whereas those of cultivars with Fhb2 or Fhb7 were 3.6. Among cultivars with two resistance QTL, the severities of cultivars with Fhb1 + Fhb4, Fhb1 + Fhb7 and Fhb4 + Fhb5 were 2.2, 3.0 and 3.6, respectively. The severity of five cultivars possessing three or four resistance QTL was below 2.5. Fhb1 and Qfhb.crc-2D showed better resistance effects than other resistance QTL.     

柴油机螺旋气道数字化设计方法

通过系统分析柴油机螺旋气道几何结构以及气道敏感区域对气道流通性能的影响关系,确定了构建螺旋气道的关键结构参数。提出了一种以气缸盖结构为约束条件,涡流比为设计目标,再进行流量系数优化的螺旋气道数字化设计方法,建立了螺旋气道参数化数学模型,开发了一款柴油机螺旋气道数字化建模软件。针对一款自主开发的卧式两缸柴油机螺旋气道的设计要求,采用螺旋气道数字化建模软件建立了螺旋气道数字化三维模型,进行了模型光顺性分析和流通性能分析。分析结果表明,螺旋气道数字化设计方法具有一定的可行性和通用性,只需提供气缸盖结构、流通性能(涡流比和流量系数)的设计要求,通过该数字化设计方法和建模软件就能设计出满足要求的螺旋气道。