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短穗兔耳草的克隆生长特征 总被引:11,自引:1,他引:10
以调查统计的方法研究了高寒草甸匍匐茎植物短穗兔耳草Lagotis brachystachya无性系的生长特征、形态特征以及能量分配规律,研究结果表明:匍匐茎只有1条的短穗兔耳草最多,占60.47%,匍匐茎有4条的短穗兔耳草只占6.98%。在牧草生长盛期,短穗兔耳草无性系的基株高度4.03 cm,根长为9.11 cm,叶数为7.98;分株高度0.85 cm,根长2.73 cm,叶数为3.08;匍匐茎的茎生叶数为12.54,长度为15.14 cm,匍匐茎比节间重为2.18 mg/cm,粗度为0.97 mm,不同构件的干质量呈现出基株>匍匐茎>分株>茎生叶的规律。随着匍匐茎数目的增多,短穗兔耳萆无性系的基株根长逐渐增加,用于克隆繁殖的能量投资也有增加的趋势,其他参数都没有明显的变化规律。 相似文献
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为了探究生长年限对衰败期苜蓿和中老龄柠条的叶片光合生理特征及土壤水分的影响,在2014年于地处黄土高原水蚀风蚀交错带强烈侵蚀中心的神木六道沟小流域,测定了不同生长年限苜蓿(ALF10、ALF13、ALF33和ALF49)和柠条(KOP10、KOP25、KOP43和KOP73)的叶片光合参数、叶结构性状参数以及0~400 cm土层土壤体积含水量(SWC0-400)。结果表明:对于衰败期苜蓿,ALF10和ALF13叶片净光合速率(Pn)差异不显著(P>0.05),而后随生长年限的延长逐渐降低,ALF33和ALF49比ALF13叶片的Pn(24.01 μmol·m-2·s-1)分别降低了2.32 μmol·m-2·s-1和7.76 μmol·m-2·s-1。相比ALF10,随生长年限延长SWC0-400恢复至10.88%(ALF13),而后随着生长年限延长降低至8.81%(ALF33)和6.12%(ALF49)。土壤水分对ALF33的限制作用不明显,水分胁迫使ALF49非气孔限制值比ALF33增大了0.340。对于中老龄期柠条,叶片Pn随生长年限的延长先升高后降低,KOP25和KOP43叶片Pn最大且两者差异不显著(P>0.05),比KOP10(6.62 μmol·m-2·s-1)分别增大了6.57 μmol·m-2·s-1和7.66 μmol·m-2·s-1,KOP73比KOP43叶片Pn降低了4.95 μmol·m-2·s-1。对于同为黄绵土生长的KOP10、KOP43和KOP73,SWC0-400随生长年限延长逐渐上升,分别为8.50%、9.06%和10.71%。土壤水分恢复使KOP43叶片气孔及非气孔限制值比KOP10柠条降低了0.185和2.180。此外,柠条叶片相对叶绿素含量(SPAD)与Pn呈极显著正相关(P<0.001),相关系数为0.514。研究结果表明衰败期苜蓿和中老龄期柠条叶片光合性能呈波动式变化,这与土壤水分的相互作用有关。 相似文献
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This paper evaluates the perception of crowding, its determinants and relationship with trail users’ experience in a peri-urban nature park. Existing crowding surveys rely heavily on a single-item 9-point crowding scale which was originally developed for backcountry areas. Receiver operating characteristic (ROC) analysis was used to test the validity and reliability of this measure in detecting crowding issues and formulating visitor capacity limits. Low validity and reliability raised concerns about the applicability of this scale in similar frontcountry areas. Inability of this simple crowding measure to detect a visitor threshold brings to the fore its another important limitation – ignorance of the complexity of crowding phenomenon. The perception of crowding varies with various social, psychological and situational factors, and a best-worst scaling (BWS) experiment was designed to simultaneously evaluate different aspects of crowding in the Medvednica Nature Park, a peri-urban nature park near Zagreb, Croatia. The findings of BWS experiment revealed that occupancy of mountain huts, number of other hikers on the trail and amount of litter along the trail on average contributed most to the trail users’ sense of crowding. A latent class analysis identified a large heterogeneity in the perception of crowding; while one group of trail users (63%) was more disturbed by the direct social impacts, the others (37%) were more disturbed by the secondary impacts of other visitors, especially by the negative externalities from road traffic in the park. Older visitors had a greater tendency to primarily associate crowding with the environmental conditions. A higher impact of trail use level in the perception of crowding, younger age and more frequent use were associated with a more negative evaluation of crowding. The park management should closely monitor road traffic in the park and visitor activity on highly used trails, especially on those popular among younger trail users. 相似文献
37.
Youjun WANG 《干旱区科学》2019,11(2):217-227
The Alagxa Plateau, in the margin of the northeastern Tibetan Plateau, is one of the most important dust source areas in East Asia, and the widespread sandy desert in the area is important both as a reservoir and a source of eolian silty. The northeastern margin of the Tibetan Plateau is one of the most actively-growing mountain belt on earth, and has large amounts of debris, with masses of fine grained material, which were continuously mobilized and deposited in the Alagxa Plateau by rivers, forming broad alluvial fans. It is possible that the role of fluvial sediments as a source of silty dust in the Alagxa Plateau has been underestimated. In this study, we test this hypothesis by investigating the iron mineralogical and geochemical characteristics of the fluvial sediments and the surface material of the sandy desert in the Alagxa Plateau, and comparing them with paleo-eolian dust deposits(loess) in the adjacent Chinese Loess Plateau(CLP) to investigate the possible linkages among the fluvial sediments, sandy desert and the last glacial loess of the CLP. The results show that sandy desert typically have high contents of goethite, and high ratios of goethite to hematite, similar to the fluvial sediments in the Alagxa Plateau. Based on the major element characteristics, field investigations and the results of previous studies, we found a genetic link between the silt component of the fluvial sediments and the sandy desert in the Alagxa Plateau with high value of Gt(goethite) and similarity of the Gt/(Hm(hematite)+Gt) ratio. But the silt component of the sandy desert main come from the adjacent fluvial sediments. The iron mineralogical characteristics(χ(magnetic susceptibility), χARM(anhysteretic susceptibility), SIRM(saturation isothermal remanent magnetization) and SIRM_(AF100 mT)(SIRM demagnetized at 100 mT)) of the CLP samples overlap with those of the fluvial sediments in the Alagxa Plateau, but there is a mismatch with the sandy desert samples. This suggests that the fluvial sediments are the source of a large amount of silty material which could be transported to the CLP. Therefore, we conclude that the fluvial sediment in the Alagxa Plateau is an important source of eolian silt, which is deposited in downwind region, and that this source has been previously underestimated. 相似文献
38.
不同氮素水平下双季稻株型与冠层内光截获特征研究 总被引:1,自引:0,他引:1
本文旨在阐明双季稻株型与冠层内光合有效辐射截获的时空分布特征。选用4个不同株型早、晚稻品种,设置4个不同施氮水平,系统观测其植株形态和冠层内光合有效辐射截获率(IPAR)的时空分布状况。结果表明,施氮水平对早、晚稻株高、穗长、叶长和叶基角均有显著影响,均表现为随施氮水平的增加而增大;早、晚稻孕穗期的分层叶面积指数(LAI)和向上累积LAI大于抽穗后12 d,分层LAI呈冠层中部大于上部和下部的分布特征,最大分层LAI出现在0.58相对高度处;冠层上中部分层LAI和向上累积LAI随施氮水平的增加而增大;向上累积LAI随相对高度呈S型曲线分布,可用Logistic方程定量描述(R~2 0.99);早、晚稻孕穗期的冠层IPAR大于抽穗后12 d,且随施氮水平的增加而增大,其日变化表现为正午较小,早晚较大;株型紧凑的早、晚稻品种,冠层IPAR低;冠层IPAR与向下累积LAI之间的关系可用方程IPAR=a (1-e~(-b×LAI))定量描述(R~2 0.88);冠层内IPAR的三维空间分布表现为冠层上中部水平面上IPAR较低,光斑变化大,冠层下部水平面上IPAR较高,光斑变化较平缓,同一冠层高度水平面上的IPAR呈不均匀分布。研究结果可为双季稻高产栽培及理想株型的优化设计提供支撑。 相似文献
39.
辣椒GRAS家族全基因组鉴定与表达分析 总被引:1,自引:0,他引:1
基于辣椒全基因组数据信息,利用生物信息学方法对CaGRAS基因家族进行了系统鉴定和进化分析,并通过Real-time PCR方法检测了CaGRAS家族组织表达模式和对PEG6000、盐胁迫的应答。结果表明:在辣椒中存在54个CaGRAS基因,除11号染色体外其余染色体均有分布,外显子数1~3,等电点4.97~9.13;系统进化分析显示CaGRAS基因可分为8个进化群;CaGRAS基因具有不同的表达模式,在根、茎、叶片和茎尖中优势表达的基因分别有34、8、3和8个;多数CaGRAS基因能响应PEG6000和盐胁迫,其中CaGRAS11、CaGRAS30、CaGRAS40、CaGRAS44和CaGRAS50受到PEG6000和盐胁迫的强烈诱导。本研究为深入解析CaGRAS家族基因的功能奠定了一定基础。 相似文献
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