湖南省双季稻田土壤无机磷形态的分级研究

为弄清湖南省双季稻田土壤无机磷的形态及其与土壤有效磷的关系,运用张氏法和蒋氏法两个分级体系对湖南省临澧、醴陵、湘乡３县（市）双季稻田土壤无机磷形态进行分级研究．结果表明,风化程度较高的第四纪红土母质发育的红黄泥田,土壤无机磷以Ｏ－Ｐ和Ｆｅ－Ｐ为主,占无机磷总量的７８．７％;而风化程度较低的紫泥田和河沙泥田,土壤无机磷以Ｃａ－Ｐ为主,分别占无机磷总量的４７．０％和４５．９％,Ｆｅ－Ｐ和Ｏ－Ｐ也占了相当大的比例,大致与Ｃａ－Ｐ的含量相当,但无机磷的总量较红黄泥田高．相关分析结果表明,Ｆｅ－Ｐ,Ｃａ２－Ｐ和Ａｌ－Ｐ与有效磷之间均呈极显著的正相关,是土壤有效磷的主要来源．蒋氏法不仅适用于北方的石灰性土壤无机磷形态的区分,同样适用于南方大面积分布的中、酸性双季稻田土壤无机磷形态的区分．     

天然沸石对松嫩平原黑钙土理化性质和保水能力的影响

目的通过研究天然沸石掺配量对于松嫩平原黑钙土理化性质和土壤水分特征曲线的影响,来研究天然沸石改良黑钙土的保水能力的效果,为改良土壤保水性提供理论参考。方法采用天然沸石改良土壤,进行60 d花盆培养,环刀法测量土壤密度,公式法计算土壤总孔隙度、毛管孔隙度、通气孔隙度。离心机法测定土壤水分特征曲线。结果天然沸石改良黑钙土试验中,土壤密度随沸石掺配量的增加而增大,呈正相关关系,当沸石掺配量为10%时,土壤密度增加最为显著;毛管孔隙度和总孔隙度均随掺配量的增加而减小,呈负相关关系,当沸石掺配量为10%时,土壤的通气孔隙度为最大。各掺配量下土壤的持水能力结果为:20%天然沸石(NZ)>15%NZ≈10%NZ>5%NZ>CK。各组土壤的水分特征曲线均能用Gardner模型拟合。Gardner模型方程的拟合系数a、b均随持水能力增强而减小,呈负相关关系;随饱和含水率升高而增大,呈正相关关系。将饱和含水率和拟合系数a进行拟合,结果显示决定系数(R2)为0.941 8。结论在进行土壤持水能力改良时,利用10%天然沸石掺配量比较经济可行。土壤饱和含水率高,不一定水分特征曲线初始水平就高。各项试验结果说明,利用天然沸石可以有效改良砂壤黑钙土的保水能力,为黑土区土壤改良提供试验和理论参考。      

施氮量对超高产冬小麦花后光合特性及产量的影响

为给冬小麦超高产栽培中氮肥合理运筹提供参考依据,于2007-2008年在河南温县、兰考两试验点,以两个具有超高产潜力的冬小麦品种豫麦49和兰考矮早八为供试材料,在全生育期施氮0、90、180、270 和360 kg N ·hm-2（底施和拔节期追施各半）的条件下,研究了施氮量对冬小麦光合特性、干物质积累和籽粒产量的影响。结果表明,两试验点施氮量180和270 kg·hm-2处理的籽粒产量均达到了每公顷9 000 kg以上的水平,高于其他施氮处理,与不施氮和90 kg N ·hm-2处理间差异均达显著水平。进一步分析发现,与其他处理相比,180和270 kg·hm-2处理提高了两个小麦品种开花后旗叶光合速率和SPAD值,进而增加了花后干物质积累量。两试验点的施氮处理对大穗型品种兰考矮早八成穗数影响不显著,而施氮量180和270 kg·hm-2处理显著提高了多穗型品种豫麦49的成穗数;两品种穗粒数和粒重均表现为不施氮和90 kg N ·hm-2处理显著低于适宜施氮量（180和270 kg N ·hm-2）处理。两品种在两试验点获得最高产量的施氮量不同,豫麦49和兰考矮早八分别在270和180 kg·hm-2获得最高产量。由此可见,在本试验条件下,两个品种在施氮量180~270 kg·hm-2、基施和拔节期比例5∶5条件下,在稳定足够穗数的基础上,增加穗粒数,促进花后物质积累量,提高粒重,可实现超高产。     

新形势下湖北棉花育种方向的商榷

湖北棉花育种水平较高,基本能满足湖北省作为植棉大省的需要。随着抗虫杂交棉的大面积应用,给棉花育种工作带来了新的问题和挑战。在分析近年来湖北省育成棉花品种情况、育种现状及存在主要问题的基础上,探讨了湖北棉花育种发展方向,认为今后应加强常规棉选育、加强育种方法创新和杂种优势利用研究。     

大豆疫霉根腐病研究进展

从大豆疫霉根腐病病害的起源、生理小种的分化、病害的流行、抗源筛选、抗性机制等方面,综述了国内外该病的研究进展。     

Age structure of Tilia broad-leaved Korean pine forest on northern slope of Changbai Mountain

IntroductionAgestructureoftrees,whichreflcctsrcge11eratio11processandvelocity,meansquantityoftreesdividingbyage.Broad-leavedKoreanpineforestwastl1etypicalzol1alvegetationofChangbaiMountaininNortheastO1ina,anditwastheprimarygymnospermconununitysurvivedaftertheQuatemaryGlacierPeriod.Alotofcommunityinf`)r-mationaccumulatCdinthestr-uctllreofforeststandsa11dgrowingprocessofindividualtrees.So,athoroughstUdyonagestructureanditsdistributiol1ofbroad-leavedKore-anpine.forestwouldprovidetl1eoretical…     

Evolution of soil microbial biomass in restoration process of Robinia pseudoacacia plantations in an eroded environment

Vegetation recovery is a key measure to improve ecosystems in the Loess Plateau in China. To understand the evolution of soil microorganisms in forest plantations in the hilly areas of the Loess Plateau, the soil microbial biomass, microbial respiration and physical and chemical properties of the soil of Robinia pseudoacacia plantations were studied. In this study, eight forest soils of different age classes were used to study the evolution of soil microbial biomass, while a farmland and a native forest community of Platycladus orientalis L. were chosen as controls. By measuring soil microbial biomass, metabolic quotient, and physical and chemical properties, it can be concluded that soil quality was improved steadily after planting. Soil microbial biomass of C, N and P (SMBC, SMBN and SMBP) increased significantly after 10 to 15 years of afforestation and vegetation recovery. A relatively stable state of soil microbial biomass was maintained in near-mature or mature plantations. There was an increase of soil microbial biomass appearing at the end of the mature stage. After 50 years of afforestation and vegetation recovery, compared with those in farmland, the soil microbial biomass of C, N and P increased by 213%, 201% and 83% respectively, but only accounting for 51%, 55% and 61% of the increase in P. orientalis forest. Microbial soil respiration was enhanced in the early stages, and then weakened in the later stage after restoration, which was different from the change of soil organic carbon. The metabolic quotient (qCO₂) was significantly higher in the soils of the P. orientalis forest than that in farmland at the early restoration stage and then decreased rapidly. After 25 years of afforestation and vegetation recovery, qCO₂ in soils of the R. pseudoacacia forest was lower than that in the farmland soil, and reached a minimum after 50 years, which was close to that of the P. orientalis forest. A significant relationship was found among soil microbial biomass, qCO₂ and physical and chemical properties and restoration duration. Therefore, we conclude that it is possible to artificially improve the ecological environment and soil quality in the hilly area of the Loess Plateau; a long time, even more than 100 years, is needed to reach the climax of the present natural forest. __________ Translated from Acta Ecologica Sinica, 2007, 27(3): 909–917 [译自: 生态学报]     

裂腹鱼类种质多样性研究综述

裂腹鱼类隶属于鲤形目鲤科裂腹鱼亚科,目前已记录有12属90种（亚种）,是鲤科鱼类中唯一适应于亚洲中部青藏高原地区自然条件的一个自然类群。整个裂腹鱼类呈现出以青藏高原为中心的分布格局,中国是世界上裂腹鱼类种类分布最多的国家。目前,随着对鱼类种质资源的研究越来越受到人们的关注,裂腹鱼类作为产地名贵经济鱼类,其种质资源已成为了研究的热点。此文重点从形态分类、物种多样性、地理分布、细胞水平、生化水平和分子水平,对多年来裂腹鱼类种质资源研究方面的进展进行综述,以期为裂腹鱼类资源的保护和利用提供基础资料。     

九峰科技植物资源现状与保护对策

经过查阅历史档案、询问当事人及外业核查、调查,结果表明:九峰地区现有39块试验现场,面积124.7hm^2;实施各类科技项目53项,项目规模面积140.25hm^2,涉及裸子、被子等植物73科,150属,194种(类),已形成科技植物群体;在九峰森林植物本底调查、林木种质资源收集与保存、林木品种遗传改良及繁殖技术等13个学科方向及近120个植物品种开发研究方面取得了重大突破和创新;鉴于九峰科技植物资源现状,本文提出了相应的保护对策与措施。     

The use of T‐DNA tagging to isolate mutants of Colletotrichum gloeosporioides and Colletotrichum acutatum with reduced virulence against Hevea brasiliensis

Agrobacterium tumefaciens‐mediated transformation (ATMT) is being increasingly recognized as an effective insertional mutagenesis tool in studies of filamentous fungi for gene discovery and functional analysis. We developed and optimized ATMT for 2 Colletotrichum species, Colletotrichum gloeosporioides and Colletotrichum acutatum, the causative agents of Colletotrichum leaf disease in rubber trees in Southern China. A. tumefaciens strain AGL‐1 carrying an ILV1 gene and a green fluorescent protein gene were used to transform the conidia of these 2 Colletotrichum species. The transformation efficiency was correlated with the co‐cultivation duration and bacterial cell concentrations, which reached 300–400 transformants per 1 × 10⁶ conidia after optimization. Southern blot analysis indicated that about 60.0% of the C. gloeosporioides transformants and 46.2% of the C. acutatum transformants had a single copy of T‐DNA in their genomes. Fungal genomic DNA segments flanking the T‐DNA were identified in the transformants through thermal asymmetrical interlaced polymerase chain reaction followed by sequencing. The flanking sequences from 4 C. acutatum and 7 C. gloeosporioides transformants showed moderate or weak homology to the NCBI database entries. Some sequences matching those reported virulence‐related genes. The results suggest that the T‐DNA inserted mutants banks constructed are useful for the discovery of new or important genes and to elucidate their function in the 2 Colletotrichum species.