5种石斑鱼遗传差异的RAPD分析

运用随机扩增多态性DNA（random amplified polymorphic DNA,RAPD）技术对鞍带石斑鱼（Epinephelus lanceolatus）、驼背鲈（Cromileptes altivelis）、棕点石斑鱼（E.fuscoguttatus）、斜带石斑鱼（E.coioides）和鲑点石斑鱼（E.fario）的遗传多样性及系统发生进行了研究。从120个RAPD随机引物中筛选出扩增效果好的引物19个,分别用于5种石斑鱼基因组DNA的扩增。结果显示,5种石斑鱼平均多态性位点比率（P）分别为64.23%,72.61%,60.34%,69.97%,73.94%;个体间平均遗传相似系数（S）分别为0.8238,0.8110,0.8345,0.8277,0.8064;平均遗传距离（D）分别为0.1762,0.1890,0.1655,0.1723,0.1936;平均Nei基因多样性指数（H）分别为0.1189,0.1364,0.1028,0.1439,0.1648;平均Shannon信息指数（Hi）分别为0.1801,0.1992,0.1530,0.2100,0.2434。5个种间的遗传距离（Dxy）在0.3964～0.6085之间。     

玉米新品种正大305的选育研究

正大305是以自选系CTL101为母本,自选系CTL102为父本杂交选育的玉米单交种。在各级试验中表现为高产、稳产、多抗,两年区试比对照农大108、郑单958平均增产9.4%,2006年1月通过辽宁省农作物品种审定委员会审定。适宜在辽宁省郑单958种植的地区种植,适宜密度42 000～45 000株/hm2。     

贵州省主要自育杂交水稻超高产潜力研究

[目的]为提高水稻的单产水平提供理论依据。[方法]以水稻品种黔优88、益农1号和黔南优2058、Ⅱ优838（对照）为供试材料，研究了不同品种的高产特性。[结果]黔优88、益农1号和黔南优2058的产量分别为12990．0、12823．5和12460．5kg／hm^2，分别比对照Ⅱ优838增产20．0％、18．5％和15．1％。与对照Ⅱ优838相比，黔优88、益农1号和黔南优2058的有效穗增加15．1％、24．5％和3．5％；千粒重分别高2．7％、4．2％和11．4％；总颖花数分别增加10．5％、11．7％和8．3％，生物产量分别高187．0、98．0和220．0g/m^2。黔优88和益农1号库容量分别比Ⅱ优838大13．4％和16．4％。上述3个品种的干物质生产优势表现在中期和后期。[结论]黔优88、益农1号和黔南优2058的平均产量达到12757．5kg／hm^2。     

优质早籼三系不育系贺50A选育

贺50A是以金23A为母本，中9B／161—5B／金23B的F4代单株为父本，经多代择优回交与选择育成的早籼型三系不育系。该不育系具有不育性稳定，株叶形态好，生育期适中，开花习性好，柱头外露率和异交结实率高，米质较优，配合力强等特点。介绍了贺50A的繁殖制种技术要点。     

转基因741杨高效配套育苗体系建立

针对转基因741杨硬枝扦插难生根的特性，将组织培养及多种扦插繁殖技术有机结合在一起，建立了转基因741杨综合配套育苗体系，提出了适合无性繁殖的“遮阴间歇喷雾扦插”和“移棚不移苗扦插繁殖”育苗方法。转基因741杨组培快繁中，初始启动培养基为MS 6-BA1．0mg／L NAA0．1ms／L，嫩茎增殖培养基为MS 6-BA0．3～1．0mg／L IBA0～0．3mg／L，茎尖生根培养基为1／2MS 0．3IBA 1．5％蔗糖。不同月份嫩枝扦插培养的苗木中，5月份扦插的嫩枝生长较快，但苗木间分化程度较高；8月份扦插的嫩枝生长相对较慢，但苗木的分化程度低，生长整齐。不同月份苗木移栽后，生长节律相同，经过1a生长，不同月份间苗木生长差异不明显，5月份扦插的苗木生长略优于其他月份扦插的苗木。     

Effects of nitrogen and phosphorus fertilization on the growth and nutrition of hybrid poplars on Vancouver Island

The effects of nitrogen (N) and phosphorus (P) rates, P source, and method of P application were tested on growth and nutrition of four clones of hybrid poplar (Populus trichocarpa Torr. & Gray×P. deltoides Bartr. ex Marsh or P. trichocarpa×P. maximowiczii A. Henry) in a plantation on Vancouver Island. Treatments were applied shortly after planting. Nitrogen (0, 500kgNha^–1) was supplied as ammonium sulfate (AS); half of the AS was added at the start of the second growing season. Phosphorus (0, 100, 200kgPha^–1) was supplied as triple super phosphate (TSP), rock phosphate (RP), or diammonium phosphate (DAP) and banded or broadcast. Over four growing seasons, stem volumes increased with AS and P additions. The effects of AS and P each were greatest when the other was also added. Volume was greater when P was applied at 100kgha^–1 than in the P control and did not significantly increase further at 200kgPha^–1. Phosphorus additions were more effective when added as TSP or DAP than when added as RP, but only in P100 and when banded. Banding increased volume when P was applied at 200kgha^–1, but increases were significant only for DAP fertilized trees. Roto-tilling associated with the banding treatment also increased volume when AS and P were not added. Rankings of clones with respect to stem volume varied with N supply and changed over time.     

Deformation analysis of timber-framed panel dome structure I: simulation of a dome model connected by elastic springs

This study develops an analytical method that enables the simulation of the deformation of timber-framed plywood panel dome structures, of which strength is largely governed by the rigidity of joints. A hybrid truss structure model was employed to analyze this structure. In this model, we aimed to incorporate the mechanical properties of bolted and nailed joints, which were employed to build the structures, although the present investigation focused on the deformation characteristics of a dome in which the panel elements were connected mutually by elastic springs. The results of the theoretical analysis are compared with those obtained by experiments. The simulated results were found to be in good agreement with the results of the experiments under similar loading conditions.     

Age trends in the genetic parameters of wood density and the relationship with growth rates in hybrid larch (Larix gmelinii var. japonica × L. kaempferi) F1

Age trends in variance components and heritability of overall wood density, earlywood and latewood density, and latewood proportion were investigated in 29-year-old trees of 19 full-sib families of hybrid larch (Larix gmelinii var. japonica × Larix kaempferi) F₁. The age–age correlation and optimum selection age for these traits were also estimated and genetic and phenotypic correlations between wood density and radial growth rate were calculated for each growth ring. Intraring wood density data were obtained using X-ray densitometry. The coefficient of additive genetic variance was stable over all ages, whereas the coefficient of environmental variances gradually decreased with increasing age, resulting in increases in heritability estimates with age for overall density. The latewood proportion had the highest heritability estimates at all ages, ranging from 0.44 to 0.66. Overall density and its various components at 28 years of age showed strong genetic correlations with their respective traits at all younger ages. Optimum selection ages for the wood density traits ranged from 8 to 14 years, at which point maximum gain efficiencies per year were obtained. There were negative correlations between wood density and radial growth rate at early ages, although these relationships tended to be weaker with increasing age. These results suggest that selection at a young age is effective for wood density, but particular care must be taken in selecting trees with an improved radial growth rate because rapid growth will result in a low-density wood product, especially in the early growth period.     

A Review of Fine Root Dynamics in Populus Plantations

Production of native and hybridized varieties of Populus has received considerable interest in temperate regions as an alternative to agricultural crops and an additional wood source, while acting as a potential carbon (C) sink to offset emissions of fossil fuel-based greenhouse gases. Research of root system dynamics in Populus species is expanding, however, our understanding of the nature and role of fine roots (FR) is incomplete. The study objective, therefore, was to review the literature regarding FR production, mortality and longevity in Populus, and evaluate the magnitude and significance of the FR fraction to C sequestration. FRs, conventionally defined as less than 2 mm in diameter and responsible for water and nutrient uptake, are an essential component of the tree. Populus FRs are relatively short-lived, with reported lifespans ranging from 30 to 300 days, depending on root diameter, tree species and age, and soil environmental factors. Standing FR biomass fluctuates throughout the growing season. Fine root production generally peaks in mid-summer, and ranges between 1.0 and 5.0 mg ha⁻¹ yr⁻¹, while FR mortality has less seasonal amplitude. Production and mortality dynamics in Populus are highly plastic in response to soil environmental conditions, and although opposing conclusions have been proposed, research suggests soil moisture and nitrogen to be most important. Results from the literature indicate annual FR turnover to the soil C pool may be small (0.2–1.6 mg C ha⁻¹ yr⁻¹), but substantial in maintaining or enhancing C levels in natural and managed stands of Populus.     

双充种型孔滚筒式杂交稻育秧精密播种器设计与试验

目的 为满足杂交稻钵苗育秧低播量精密播种的农艺要求,解决型孔滚筒式育秧播种器作业过程中稻种在充种室流动性差、充种可靠性低、漏播指数高以及型孔易堵塞等问题,设计一种双充种型孔滚筒式杂交稻育秧精密播种器。方法 基于PLC控制技术,搭建型孔充种性能检测与控制系统,对播种器的关键部件进行设计,并通过EDEM离散元软件开展不同型孔形状、第一充种室充种位置角及生产率对充种性能影响的仿真试验,对第一充种区的型孔滚筒工作参数进行优化。研制试验样机并进行性能试验,试验材料为‘培杂泰丰’杂交稻。试验分2步：第1步,第二充种机构不动作,采用三因素三水平正交试验,研究型孔深度、生产率和第一充种室充种位置角对试验指标的影响,验证仿真准确性;第2步,启动第二充种机构,研究进行双充种作用下的不同振动频率对试验指标的影响,探明设计第二充种机构后播种性能。结果 第1步试验结果表明,影响播种合格指数与重播指数的因素主次顺序为型孔深度>生产率>第一充种室充种位置角;影响漏播指数的因素主次顺序为生产率>型孔深度>第一充种室充种位置角。第2步试验结果表明,当型孔形状为椭圆凹槽形,第一充种室的充种位置角为35°、第二充种室振动频率为27 Hz、生产率在400~600盘/h,播种合格指数均大于90%,漏播指数均小于3%,试验结果满足杂交稻低播量精密播种的农艺要求。结论 采用双充种的填充方式改善了播种器每穴的填充性能,减少了漏播指数,本研究结果为轻简型杂交稻钵苗育秧精密播种机的开发提供了理论依据。