共查询到10条相似文献，搜索用时 46 毫秒
1.
20%苍耳素乳油对苹果斑点落叶病的田间药效试验 总被引：1，自引：0，他引：1
田间药效试验结果表明:20%苍耳素乳油对苹果斑点落叶病具有很好的防效,20%苍耳素乳油500倍、300倍和100倍3种处理剂量在春稍停止生长后10 d的防效分别为69.7%、81.6%和85.9%,其中100倍液防治效果与20%的多菌灵防效80.9%呈显著差异;在末次施药后10 d供试药剂3个处理剂量的防效分别为65.5%、76.2%和78.8%,对照药剂50%多菌灵则为77.5%,方差分析表明,20%苍耳素乳油300倍、100倍液防效与对照药剂防效相当。 相似文献
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Asaresultofti1econunoncalculatingmethodllJofinertiamomentofcranemecha-nismbeingverycomplicatedandoverelabo-rate'anewcalculatingmethodhasbeenputforwardlz](Simplycallednewmethod).Butthenewmethodisonlysuitableforthecalculationofinertiamoment0flifting,tfavelingandro-tarymechanism'sloadingmovemass.WhetherornotcanwefindabettercalculatingmethodWhichhasdefiniteconcept,clearthinking,simpleconvenienceandbecomesinconunon?Thismethodwillbenotonlysuitableforcalcu-latil1ginertamomentonloadingmovemassoffourm… 相似文献
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The stomatal behavior of Adenophora lobophylla of different age structures was studied in July 1995 in greenhouse of the Harbin Forest Farm of Northeast Forestry University by means of shading experiment. The effects of different shading treatments on the stomatal physiological character and ecological adaptation of A. lo-bophylla of different ages were compared. The results showed that the morphological characters of annual A. lo-bophylla were more obvious than that of the perennial, but the stomatal density of annual was less than that of perennial. Growth of annual A. lobophylla was more sensitive to the change of environment than that of the peren-nial. The ecological adaptation of annual was weak, which was one of the main causes of endangered population. 相似文献
4.
The effects of disturbance on the stability of the eucalypt forest are considered in terms of Bormann and Likens' (1979) schema of reorganisation, aggradation, transition and steady state phases of secondary succession.The difficulties of making reliable estimates of ecosystem nutrient reserves are discussed against a background of anisotropic nutrient distribution, inadequate knowledge of the volume of soil effectively exploited by roots, and the limitations of existing techniques for soil chemical analysis. The relative significance of the atmosphere and parent material for the accumulation of nutrient reserves is outlined and the overriding importance of the latter on soil phosphorus capital in the eucalypt forest is emphasised.The capacity of forest ecosystems to restrict changes in the ionic concentration of percolating soil water is indicated and some important facets of nutrient dynamics are described. Spatial and temporal patterns of substrate availability and microbial activity greatly complicate the measurement of organic matter decomposition and nutrient flux on the forest floor. Adaptations of eucalypts potentially significant in mineral cycling are mentioned.The role of natural agents of disturbance as determinants of pattern in plant communities is indicated, and the effects of man-induced disturbances such as clearcutting, burning of logging debris, and hazard reduction burning are discussed in the context of biogeochemical cycling. The importance of close operational control of management practices is stressed, together with the need for appropriate measures of functional stability. 相似文献
5.
热带树木构筑学研究概述 总被引：10，自引：2，他引：8
热带树木构筑型研究是热带树种结构多样性研究的一个重要方面。本文简要叙述了热带树木构筑学的发展过程,介绍了热带树木的不同形成方式及构筑的主要要素。树木不同部分的发育顺序,顶端分生组织的活动方式,树木的延长生长与分枝方式等是热带树木构筑型的主要分类要素。 相似文献
6.
影响树木蒸腾耗水的外部因子研究进展 总被引：1，自引：0，他引：1
国内外研究表明,影响树木蒸腾耗水的外部因子主要由2部分构成:一是土壤因子,二是气象因子,包括光照、温度及空气相对湿度等。分析得出这两类因子影响树木耗水的一般规律为:(1)在土壤水分超过树木日需求量平均值过多时,叶片气孔在数小时内迅速关闭,导致树木蒸腾耗水量曲线呈下降趋势;在土壤水分低于树木日需求量平均值过多时,树木的生长受到限制,叶片水势下降,导致蒸腾耗水也相应下降。(2)在一定范围内,树木蒸腾耗水量会随着光照强度、大气温度的增加而增大,随着空气相对湿度的增加而减少。同时,这些因子间的互相作用也影响着树木的耗水。 相似文献
7.
沙棘林木生长与地上部生物量动态 总被引：2，自引：0，他引：2
依据１９９８年在半干旱黄土丘陵区安塞、吴旗的调查资料,对沙棘年生长及单株地上部生物量进行了分析。结果表明：（１）时间的三次系基式与生长的关系能较好地反映生长期内生长与时间的关系;（２）沙棘单株地上部各器官生物量占地上部生物量的分配比率顺序为：枝〉茎〉叶〉桔枝;且枝、叶、枯枝生物量与树彰有十分显著的相关关系,茎与树龄间有的相关关系;（３）可用树高、地径、树个械模型与地径、冠幅、多年生枝长结合模型估测 相似文献
8.
不同种源香椿抗寒性试验 总被引：1，自引：0，他引：1
以河南西峡等10个种源1年生香椿为材料,研究了不同低温处理条件下离体茎段的相对电导率,并与活体茎段及自然降温过程中各种源的表现进行了分析比较.用Logistic方程拟合曲线,求出拐点温度即低温半致死温度(LT_50),作为评价各种源香椿抗寒能力的参考指标.结果表明:各种源离体茎段相对电导率随处理温度的降低而呈"S"形曲线上升,其LT_50最低者为山东济南种源为-7.94℃,最高者为福建霞浦种源为-3.88℃;10个种源香椿抗寒性由大到小依次为山东济南、山东荷泽、河南西峡、陕西安康、江苏南京、四川广元、湖南洞口、湖北随州、贵州黔西南、福建霞浦,与大田自然越冬条件下各种源的表现基本一致. 相似文献
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