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31.
以河西走廊东部1998—2007年麦红吸浆虫和气象资料为基础,分析了麦红吸浆虫的发生关键期、动态和气象成因,运用SPSS统计软件建立了气象预测模型。结果表明:(1)影响河西走廊东部麦红吸浆虫发生的主要气象因子是温度和水分,特别是后冬(2月)温度越低麦红吸浆虫破茧、化蛹、成虫始见越迟;2—5月水分因子促进麦红吸浆虫的发生发展;10cm地温与麦红吸浆虫的活动相关性显著,10cm地温指标高于平原地区渡河两岸6~8℃。(2)麦红吸浆虫越冬基数受9月平均最低温度制约显著。(3)1月极端最低地温和6月中旬-7月上句平均气温是影响当年麦红吸浆虫发生面积的前期和后期的主要气象影响因子。 相似文献
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通过单因素及多因素试验,探讨抑制荸荠中多酚氧化酶活性的效果。L_9(3~3)正交试验结果表明:柠檬酸预煮液的质量分数0.5%,预煮温度100℃,预煮时间5 min为最优预煮条件。 相似文献
34.
植酸酶基因PhyA对陆地棉产量性状的影响 总被引:1,自引:0,他引:1
在人工控制(培养基、水培、沙培)条件下,植酸酶基因PhyA具有分解利用培养基质植酸磷、提高磷素利用效率的功能,但在田间的表现目前尚未明确。在前期完成的PhyA转基因陆地棉新材料盆栽试验基础上,将其种植在田间条件下,研究PhyA基因对棉花产量性状的影响。结果表明,部分转基因棉花新材料的单株结铃数、铃重、衣分、籽棉产量、皮棉产量与野生型对照存在显著差异,PhyA在田间条件下具有改良转基因棉花部分产量性状的能力。在此基础上,遴选出2个转PhyA棉花优良新品系G3、G2,可用作今后转植酸酶基因棉花新品种培育的基础材料。 相似文献
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贮藏条件是影响双孢蘑菇贮藏效果的重要因素,介绍了气体成分、温度和湿度等因素对双孢蘑菇生理生化变化的影响。 相似文献
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38.
Logging pattern and landscape changes over the last century at the boreal and deciduous forest transition in Eastern Canada 总被引:4,自引:0,他引:4
Forestry practices associated with the industrial era (since ~1900) have altered the natural disturbance regimes and greatly
impacted the world’s forests. We quantified twentieth century logging patterns and regional scale consequences in three sub-boreal
forest landscapes of Eastern Canada (117,000, 49,400 and 92,300 ha), comparing forestry maps depicting age and forest cover
types for early industrial (1930) and present-day (2000) conditions. Results were similar for the three landscapes, indicating
large-scale forest change during the twentieth century. In 1930, previous logging activities had been concentrated in the
lowlands and along the main hydrographical network, as compared to a more even distribution over the landscapes in 2000, reflecting
a decreasing influence of the environmental constraints on forest harvesting. In 1930, old-aged forests (>100 years) accounted
for more than 75% of the unlogged areas of the three landscapes, as compared to less than 15% for the present-day conditions.
Logging practices have thus inverted the stand age distribution of the landscapes that are currently dominated by young and
regenerating stands. The 1930 forest cover types showed a clear relationship with elevation, with conifers located in the
lowlands and mixed and deciduous stands restricted to the upper slopes. Between 1930 and 2000, 58–64% of the conifer areas
transformed to mixed and deciduous forests, such that no clear altitudinal relationships remained in 2000. We conclude that
twentieth century logging practices have strongly altered the preindustrial vegetation patterns in our study area, to the
point that ecosystem-based management strategies should be developed to restore conifer dominance, altitudinal gradients,
as well as the irregular structure inspired from old forest stands. 相似文献
39.
小区绿化设计的理念、原则及造景 总被引:1,自引:0,他引:1
通过参考大量文献资料及深入实际调查分析研究,结合实例分析总结居住小区绿化设计中存在的几个常见的问题,提出小区绿化设计的理念、原则,并对小区绿化植物的选择与造景提出建议。 相似文献
40.
Patricia Flores Damián Poggi Stella Maris García Marcela Catraro 《International Journal of Fruit Science》2017,17(1):29-40
The objective of this work was to quantify changes in the germination capacity of Juglans nigra seeds following storage and then artificial stratification. Seeds were stored at 5 and –20 °C under 5% and 14% internal moisture content (IMC) for 0, 8, 10, and 12 months under conditions with oxygen or under vacuum. Germination percentage (GP) was affected by storage temperature, IMC, and storage period. Seeds stored with 5% IMC succeeded in germinating regardless of the temperature. Seeds stored with 14% IMC did not germinate (–20 °C) or germinated during storage (5 °C). The GP was reduced with the time of storage in seeds at –20 °C and 5% IMC and this effect was avoided in storage under vacuum. In conclusion, the germination capacity of black walnut seeds did not change for up to 12 months at low above-zero temperature and low IMC (5 °C, 5% IMC), being the most cost-effective alternative for long-term storage of black walnut seeds in commercial nurseries. Vacuum storage avoided the decrease of around 50% in average germination capacity of seeds stored for a year at –20 °C. 相似文献