共查询到20条相似文献，搜索用时 234 毫秒
1.
冬樱花物候及观赏期观测 总被引：2，自引：0，他引：2
云南各地冬樱花花期有一定差异,但大都集中在12月上旬至1月中旬,紫色叶呈现期为12月下旬至1月上旬.果实成熟期为3月至4月.最佳观花期为12月中旬至1月上旬,持续时间昆明为12～15 d,思茅和景谷为10～12 d.最佳观紫色叶期为12月下旬至1月上旬,昆明为7～8 d,思茅为4～5 d.最佳现果期昆明为4月上、中旬,持续10～15 d,思茅和景谷为3月下旬至4月上旬,10～12 d.由不同地区和同一地区不同年份冬樱花物候的差异,认为冬樱花属低温春化才能开花的植物. 相似文献
2.
本文对黄檗开花与结实性状进行了研究,结果表明:长春城市群体不同年份开花时间为5月下旬至6月上旬,花期变动于9～11 d,平均10 d,单株花期6 d;靖宇山地群体不同年份开花时间为6月上旬至下旬,花期变动于12～14 d,平均13 d,开花时间较长春城市群体晚10～15 d.长春城市群体不同年份花前≥10℃有效积温变动于514～597℃,平均576℃;靖宇山地群体变动于601～685℃,平均652℃.花前有效积温的高低是影响开花时间早晚的主要环境因子,在相对有限的地理区域内,低纬度山区的黄檗开花时间要晚于高纬度的平原地区.传粉受精后,子房开始迅速膨大,果实发育至第42 d时,平均横径9 mm、纵径10 mm,最大横径11 mm、纵径12 mm,最小横径7 mm、纵径8 mm,至此体量不再增加直至成熟,早期发育快于晚期.果实未成熟时均为绿色,至8月下旬果皮开始泛黄,并逐渐出现蓝黑色,至9月下旬呈蓝黑色,完成生理与形态成熟;10月上旬开始有果实凋落,至11月末基本全部凋落,相同时间内不同母树间落果量存在差异.各雌株果实成熟时鲜重差异显著,5号雌株最重(每300枚质量为276.81 g),为2号雌株(每300枚质量为110.68 g)的2.5倍.结实有大小年现象,长春市栽培群体每2年或3年丰收一次;同年株间结实状态高度同步,但结实量差异显著. 相似文献
3.
以长春市建植小叶女贞庭院绿篱为研究材料,观测群体花期、单株花期、单花序与单花花期,收集5月份有关气温数据,分析其对花期性状表现是否构成影响及程度。结果表明:2014—2016年小叶女贞开花时间为6月2日至25日之间,3 a群体花期平均为21.3 d,各年度相差在1 d之内,盛花期为12~13 d;单株开花时间最短植株为16 d,最长者为19 d,平均为17.5 d;单花序为8~12 d,单花为4~5 d。小叶女贞为夏初开花树种,此时气温等气象因子稳定,花期基本不受天气微小变化影响,开花时间亦相对稳定。 相似文献
4.
凤凰木常见的病虫害及防治要领 总被引：1，自引：0，他引：1
正凤凰木植株高大,树形美观,树冠横展而下垂,浓密阔大而招风,耐干旱耐瘠薄,不耐寒,喜高温,须在阳光充足处方能繁茂生长,种植6~8年开始开花,花朵颜色艳丽。在华南地区,每年2月初萌发冬芽,4~7月为生长高峰,7月下旬因气温过高,生长量下降,8月中下旬以后气温下降,生长加快,10月份后生长减慢,12月至翌年1月份落叶,是常见的景观绿化树种。 相似文献
5.
后斑小瓢虫是竹茎扁蚜最重要的捕食性天敌之一,本文描述了其各虫态各龄期的形态特征,并对其生物学特性进行了观察,发现后斑小瓢虫在福建武夷山一年发生4～5代,有世代重叠现象,从卵发育到成虫约需21 d,成虫寿命一般为26 d,幼虫和成虫都有捕食性。每年4月下旬至6月下旬虫口数量达到高峰。研究可为野外快速辨认该种瓢虫和天敌资源利用提供参考。 相似文献
6.
7.
8.
9.
10.
11.
蒙链眼蝶生物学习性初步研究 总被引：2，自引：0，他引：2
蒙链眼蝶是竹子上新发生的害虫之一,在浙江省一年2代,以蛹越冬。成虫出现期为4月中旬到6月上中旬、7月下旬到8月下旬。幼虫为害期为6月中旬到7月下旬、8月中旬到10月下旬。幼虫有5龄、6龄两个龄数。各代历期平均分别为34.9天、36.6天。幼虫一生平均食叶为296 cm~2。天敌为伞裙追寄蝇,野外平均寄生率38％。 相似文献
13.
遮荫下2种热带树苗叶片光合特性和抗氧化酶系统对自然降温的响应 总被引：10，自引：0，他引：10
选取 2种遮荫条件下 (8%、2 5 %全光照 )西双版纳地区热带雨林上层树种滇南红厚壳和中层树种玉蕊的幼苗 ,测定了雨季末自然降温过程中 2种植物叶片光合特性、抗氧化酶 (SOD、CAT、APX)活性、丙二醛 (MDA)含量的变化。研究结果表明 :低温使 2种植物单位面积叶绿素含量和净光合速率明显下降 ,生长在中等光强下的幼苗比低光强下的幼苗下降的比率大 ,滇南红厚壳比玉蕊下降的比率大。在降温初期 ,即从 10月到 12月初 ,2种光强下 2种植物SOD和APX活性上升 ,CAT活性出现波动 ,黎明光化学效率和MDA含量基本没有变化 ,光合机构没有受到氧化破坏。 12月末 ,中等光强下滇南红厚壳黎明光化学效率降低 ,SOD和APX活性有所下降 ,MDA含量显著上升 ;而低光强下的滇南红厚壳和 2种光强下玉蕊SOD和APX活性仍在上升 ,MDA含量变化较小。这表明 ,2种光强下 2种热带树苗是以不同的方式响应自然降温 ,低温对中等光强下的植物比低光强下的影响大 ,上层树种滇南红厚壳受到的影响比中层树种玉蕊大。同时 ,根据降温过程中抗氧化酶活性和MDA含量的变化 ,大致可将西双版纳热带雨林幼苗对低温的响应分为 2个阶段 ,即第 1阶段为低温适应阶段 ,抗氧化酶活性上升 ,光合机构没有受到明显的氧化破坏 ;第 2阶段 ,中等光强下滇南红厚壳抗氧化酶 相似文献
14.
F. G. Rogers 《Southern Forests》2013,75(1):93-95
In the summer rainfall regions of South Africa the start of the wet season is a time of change in plant communities and is important in management. Data covering 25 years have been evaluated in an attempt to determine the start of the wet season at the Cathedral Peak State Forest in the Natal Drakensberg. In every year it had started by 5 November, but in only 24% of years had it started by 1 October. Dry periods can occur after the wet season has started and in one year a dry period of 13 days was recorded in December. 相似文献
15.
16.
We studied the effects of "near-lethal" (NL, 47 degrees C for 1 h) heat stress, applied to intact shoots of red-osier dogwood (Cornus sericea L.) during early (October), deep (November) or late (December) dormancy, on bud dormancy release and development of stem tissue cold hardiness under natural conditions and at a constant temperature of 0 or 23 degrees C in the dark. The NL heat-stress treatment overcame bud dormancy when applied during the early and late stages of dormancy. During October and December, all plants in the 23 degrees C + dark post-stress environment broke bud within 35 and 12 days, respectively, whereas the corresponding values for days to bud break in the control plants were more than 150 and 110 days, respectively. Application of NL heat stress during deep dormancy caused only slightly earlier bud break compared to the control plants. In the 0 degrees C + dark post-stress environment, all NL heat-treated plants died within 9 weeks. Under natural post-stress conditions, bud break in plants receiving NL heat stress during early and deep dormancy occurred at the same time as in control plants, whereas bud break of plants receiving NL heat stress during late dormancy occurred 55 days earlier than in control plants. Under both natural and 23 degrees C + dark post-stress conditions, cold hardiness of plants receiving NL heat stress during early dormancy was similar to that of controls. Application of NL heat stress during deep dormancy hastened the rate of deacclimation under the 23 degrees C + dark post-stress conditions but had no effect on deacclimation under natural post-stress conditions. Application of NL heat stress during late dormancy enhanced deacclimation of plants in both the 23 degrees C + dark and natural post-stress environments. 相似文献
17.
18.
19.
Denitrification rates in soils of six subalpine plant communities in an eastern Sierra Nevada watershed were determined by the acetylene inhibition method. Soil atmosphere samples were collected monthly from June 1986 through May 1987 in a riparian, wet meadow, dry meadow, north-facing forest, south-facing forest and barren site and analyzed for N2O content using gas chromatography. Soil temperature, moisture, organic matter, C,N,C:N ratio, NO3N and pH were examined to assess their effects on denitrification rates. Mean denitrification rates for the year varied from 103.3 μg m−2h−1 in the north-facing forest to 120.2 μg m−2h−1 at the barren site, but did not differ significantly among any of the six plant communities. However, comparisons among months within individual communities revealed that the denitrification rates in each community varied significantly over the year, and in three of the six sites significant correlations between denitrification rates and other soil parameters were detected. Soil acidity was positively correlated with denitrification rate in the riparian and wet meadow communities, and in the dry meadow, soil moisture was positively correlated while soil temperature and organic matter were negatively correlated with denitrification rate. Comparisons among sites within individual months revealed significant differences in denitrification rates in June, September, October and January, but no single site consistently exhibited the highest or lowest rate in all 4 months, and only in October, when denitrification rates were positively correlated with soil temperature and moisture, was variation in denitrification rates among sites explained by other soil parameters. For the six plant communities overall, soil denitrification rates were highly variable from June to October, increased sharply from October to December, and then declined from December to May. 相似文献