甘薯地下部生长对产量的影响

利用甘薯不同品种进行嫁接,研究了地下部、地上部生长的相互关系,嫁接材料砧木与接穗之间的交互作用.甘薯地下部对产量的影响大于地上部.嫁接后,砧木与接穗之间交互影响不显著,可以利用甘薯库鉴定品种产量高低.     

不同生态条件下玉米产量源库关系的研究

１９９３－１９９４年在新疆石河子、北京大兴、山东济南、江苏扬州对多花品种掖单１３和中花品种鲁玉１０进行春播试验，采用高产群体剪叶剪穗、不同密肥培植不大不同群体研究了玉米群体主要源库指标与产量的关系。结果表明：尽管玉米产量因试点经续度及生态条件的差异很大，但不同试点的玉米产量水平均随花后干物质积累量（源）、总粒数（库）的增加而增加，源库相互促进增产。但增源增产与增库产比，增库增产更为重要。这方面花数     

播期与密度组合对夏玉米群体源库关系及冠层透光率的影响

通过播种期和密度两因素耦合试验(3个播期,各播期下设3个密度)研究不同播期、密度组合对夏播玉米群体源库关系及冠层透光率的影响。结果表明:适宜播期(6月22日之前)与适当密度(半紧凑型品种"金海5号"为6.00～7.50万株·hm-2,紧凑型品种"郑单958"为6.75～8.25万株·hm-2)组合的各源库指标表现较优。叶面积指数(LAI)在吐丝期达到4.88～5.97,成熟期仍保持在2.73～4.48;群体透光率在吐丝期和成熟期分别达21.09%～34.82%和27.97%～35.29%;吐丝期穗位叶片Pn较高,达34.4～41.7μmol(CO2)·m-2·s-1;"金海5号"6月15～17日播种、播种密度为7.50万株·hm-2,"郑单958"6月15～17日播种、播种密度为8.25万株·hm-2时,均产量达到最大,分别为14863.50kg·hm-2和15123.30kg·hm-2。     

杂交中籼新组合Ⅱ优1259的主要特性与再生高产栽培研究

简述了Ⅱ优1259的基本特征特性,对其超高产特性的产量与产量构成因素进行分析,结果表明:Ⅱ优1259超高产群体形成的决定因素是库容量大,即单位面积的总颖花数与产量呈极显著正相关,每穗总粒数与产量呈显著正相关;除此之外,高光合性能的形态特征也是超高产的另一个重要因素。并对Ⅱ优1259作再生稻栽培的特性及关键栽培技术进行了研究。     

库源调节对玉米杂交种青枯病抗性的影响

以穗叶处理作为控制库源关系的手段,对玉米杂交种青枯病的抗病性进行了研究.结果表明:()库源关系对玉米杂交种的抗病性有直接影响.去穗可显著提高感病品种(掖单13)的抗性,去叶则使抗病品种(高油115)的抗病性降低.()穗叶处理间有明显的互作效应.所有处理均以去穗留叶发病率最低,以留穗去全叶的发病率最高.各叶处理对抗感品     

Estimated persistence of northern flying squirrel populations in temperate rain forest fragments of Southeast Alaska

Habitat reserves are a common strategy used to ensure viability of wildlife populations and communities. The efficacy of reserves, however, is rarely empirically evaluated. We examined the likelihood that small (650 ha), isolated habitat reserves composed of old-growth Sitka spruce (Picea sitchensis)-western hemlock (Tsuga heterophylla) rain forest (upland-OG) and mixed-conifer peatlands (peatland-MC) would sustain populations of northern flying squirrels (Glaucomys sabrinus) in the absence of immigration or emigration within the Tongass National Forest in Southeast Alaska. We used demographic data obtained from a study of flying squirrels on Prince of Wales Island in Southeast Alaska and litter size from flying squirrels in similar habitat to estimate per capita rate of increase (r) of flying squirrels in upland-OG (r = 0.14, SD = 0.42) and peatland-MC habitats (r = 0.01, SD = 0.39). Our results indicated that peatland-MC habitat was unlikely to sustain populations and that viability of flying squirrel populations in small habitat reserves largely depended on the upland-OG forest component. We subsequently estimated time to extinction (T_N) based on r, its variance (v), and the potential population ceiling (K). We used T_N to calculate the probabilities (P_t) that squirrel populations would persist in small reserves containing 100%, 50%, and 25% upland-OG habitat for 25, 50, and 100 years. In each scenario, we calculated T_N and P_t for 2 levels of v. For the best-case scenario (100% upland-OG forest, lowest variance, t = 25 years), T_N was 507 years and P_t was 0.95. For the worst-case scenario (25% upland-OG forest, highest variance, t = 100 years), T_N was 237 years and P_t was 0.66. Minimum patch size of upland-OG forest required for a high probability (P_t = 0.95) of sustaining a flying squirrel population in isolation with relatively low demographic variability (v = 0.34) for 25, 50, or 100 years was 578, 5077, and 78,935 ha, respectively. We concluded that it was unlikely that small isolated habitat reserves could sustain populations of flying squirrels for >25 years in the absence of immigration. Consequently, dispersal among small reserves is critical to ensure that they function to support metapopulations of northern flying squirrels.     

旗叶期缺磷及去蘖对小麦光合特性和磷分配的影响

采用石英砂培养方法并去除或保留分蘖，研究了旗叶期缺磷对大穗型小麦CA9325和多穗型晋麦2号（JM2）生长后期旗叶光合和蒸腾速率、干物质和磷在体内分配以及最终产量的影响。结果表明: ⑴旗叶期缺磷一段时间后降低小麦旗叶的光合和蒸腾速率。不同供磷水平下，去蘖使小麦旗叶光合和蒸腾速率大都高于同期未去蘖的；⑵旗叶期缺磷几乎导致两品种所有器官和整株干物质和磷的积累降低，去蘖的小麦籽粒干物质和磷总量占整株的比例均高于未去蘖的，说明缺磷促进小麦各营养器官的磷向籽粒转移；⑶主茎干物质和磷的积累以CA9325高于JM2，而JM2则以分蘖占优势，这与JM2分蘖数较多有关；⑷ 不论供磷还是缺磷，未去蘖的CA9325籽粒产量低于JM2，而去蘖后则相反。不同库容量的CA9325千粒重和籽粒磷含量均高于JM2。全生育期供磷条件下的磷吸收效率，以未去蘖的CA9325显著高于JM2，去蘖后两品种间无明显差异。     

库大小对水稻不同叶位叶片氮代谢的影响

采用去穗与疏花方式调节库大小，研究了对水稻不同叶位叶片氮代谢的影响。去穗或疏花后，已完成发育的源叶片，尤其是顶4叶，蛋白质合成重新旺盛，蛋白氮含量提高，出现了类似于生长库的氮代谢特征。水稻叶片的酸性转化酶活力可反映其蛋白质合成能力，据此可判断叶片是属于氮素供应源还是氮素接受库。研究证实下位叶的氮代谢     

春小麦群体库的形成及其特性分析

以春小麦两个品种内麦19和永良4为试材，在不同密度、施肥量处理下对春小麦群体库均形成与特性以及在产量形成中的作用进行了系统研究。结果表明，春小麦籽粒体积(库容量)随生育进程呈单峰曲线变化，籽粒干物重的增长(库的充实)随生育进程呈S型曲线变化；每穗结实粒数(库)与开花期群体干物质源的供应呈显著正相关。籽粒体积与灌浆速率及粒重呈极显著正相关，由此说明扩大库容(籽粒体积)，可以促进源的生产、运转与积累，提高籽粒重量。     

Contrasting measures of fitness to classify habitat quality for the black-throated sparrow (Amphispiza bilineata)

Habitat quality is an important consideration when identifying source and sink habitat and setting priority areas for avian conservation. The problem is that different measures may lead to different conclusions about habitat quality, and may also vary in the resources required to estimate them. Individual level measures, such as nest success, and fecundity, will often identify different high quality habitats than population level measures, such as abundance or the number of fledglings produced per unit area. We tested measures of fitness in the Black-throated Sparrow both at the individual and at the population level for six habitats in the northern Chihuahuan Desert, to explore their value as indicators of habitat quality. We compared clutch size, number of nestlings per nest, number of fledglings per successful nest, nest density, nest success, daily nest survival rate, season-long fecundity, number of fledglings produced per 100 ha, and adult abundance, in each habitat type. We also modeled source-sink dynamics to estimate the scale at which they operate, to infer survival rates, and to ascertain the relative source potential of each habitat. We found that fecundity is the best indicator of individual level habitat quality but a poor indicator of population level habitat quality. Nest success (or fecundity, if resources are available to adequately estimate it) plus nest density provide the most robust indicator of population level habitat quality, which is the level at which priority habitats for conservation should be identified. Mesa grassland and black grama grassland functioned as source habitats most consistently, and mesquite was consistently a sink but also probably a reservoir of individuals available to occupy other habitats.