不同用量保水剂对紫花苜蓿比叶面积和光合特征的影响

为保持与高效利用绥化地区有效降水而达到人工苜蓿草地稳产增产的目的,以保水剂不同用量（0、15、30kg.hm-2）研究其用量对紫花苜蓿比叶面积和光合特征的生理响应。结果表明：施用保水剂对紫花苜蓿比叶面积无显著影响,对叶绿素含量和光合特征有显著影响。保水剂施用量为15kg.hm-2时,保水剂能显著提高紫花苜蓿叶片的pn、gs、Tr和WUE,而保水剂施用量为30kg.hm-2时,保水剂显著降低了pn、gs和Tr,但没有影响WUE。紫花苜蓿pn与gs、pn与Tr的相关性以施用量30kg.hm-2处理最强,依次是15kg.hm-2和CK。pn与WUE以施用量15kg.hm-2处理最强,依次是CK和30kg.hm-2处理。因此,加强保水剂在苜蓿产业化生产中的应用性仍需研究。     

Association of root, specific leaf area and SPAD chlorophyll meter reading to water use efficiency of peanut under different available soil water

Drought is the major abiotic constraint affecting peanut productivity and quality worldwide. There is a pressing need to improve the water use efficiency (WUE) of rain-fed peanut production. Breeding varieties with higher water use efficiency is seen as providing part of the solution. The objectives of this work were to (i) evaluate genetic variation in WUE, harvest index, root dry weight, specific leaf area (SLA) and SPAD chlorophyll meter reading (SCMR) among peanut genotypes in response to different available soil water levels and (ii) assess the relevance of root dry weight, SLA and SCMR to WUE in peanut under receding soil moisture levels. Two greenhouse experiments were conducted in the dry and rainy seasons in 2002/2003. The 11 peanut genotypes (ICGV 98300, ICGV 98303, ICGV 98305, ICGV 98308, ICGV 98324, ICGV 98330, ICGV 98348, ICGV 98353, Tainan 9, KK 60-3 and Tifton-8) and three soil moisture levels [field capacity (FC), 2/3 available soil water (AW) and 1/3 AW] were laid out in a factorial randomized complete block design (RCBD) with six replications. At 37, 67, and 97 day after sowing (DAS), data were recorded for SLA and SCMR. Root dry weight, harvest index (HI) and WUE were recorded at harvest. Drought reduced WUE, root dry weight and HI. Across both seasons, Tifton-8 and ICGV 98300 had high WUE and also had large root systems under drought conditions. ICGV 98324 and Tifton-8 had low SLA and high SCMR under stressed and non-stressed condition. Under drought conditions, ICGV 98324 had high HI and Tifton-8 had low HI. Root dry weight had a greater contribution to WUE under well-watered and mild drought (2/3 AW). Under severe drought (1/3 AW), SLA showed a more important contribution to WUE than the other traits. Traits that were associated to high WUE under drought conditions were different among different peanut genotypes. ICGV 98300 maintained high root dry weight under 2/3 AW and ICGV 98324 maintained low SLA and high SCMR under 1/3 AW. Tifton-8 had both large root systems and low SLA associated with high WUE.     

甘肃合作猪白细胞抗原经典Ⅱ类分子DR基因克隆及生物信息学分析

为了克隆甘肃合作猪白细胞抗原(SLA)DRA和DRB基因,分析SLA-DR基因特性和抗原多态性,首次研究了甘肃合作猪在异种移植等研究领域中的应用前景.应用RT-PCR分别扩增合作猪SLA-DRA和SLA-DRB基因并进行测序,将所获得基因序列登录GenBank(登录号分别为FJ905823和FJ9058258),再用NCBI中的BLAST和ExPASy等相关软件进行生物信息学分析.发现在猪-人异种移植中,近亲繁殖的合作猪种在与人类主要组织相容性复合体遗传基因水平相似性方面有一定优势,也可作为备选猪种对相关基因进行必要的修饰和改造.     

江西４刨花楠种源苗木叶片表型性状与生物量分配的比较

采用实验地调查与统计分析方法对江西4种源刨花楠(Machilus pauhoi)苗木叶片长(LL)、宽(LW)、厚(LT)、重(LH)、叶面积(LA)及比叶面积(SLA)等表型性状与生物量分配进行比较,4种源的种子分别来自江西崇义(CY)、遂川(SC)、泰和(TH)和永新(YX)4县.结果表明:(1)刨花楠不同种源间苗木的LL、LW、LT、LH、LA与SLA存在显著差异(P＜0.05),其中,LL大小为TH＞SC＞YX＞CY,LW为CY＞TH＞SC＞YX,LT为SC＞YX＞TH＞CY,LH为TH＞CY＞SC＞YX,LA为TH＞CY＞SC＞YX,SLA为YX＞SC＞CY＞TH.(2)叶片的LL、LW、LH与LA四者间呈极显著正相关(P＜0.01);而SLA与LL、LW、LH、LA四者均呈极显著的负相关(P＜0.01),与LT虽呈负相关,但相关不显著(P＞0.05).(3)不同种源间苗木生物量存在显著差异(P＜0.05),其大小为SC＞TH＞CY＞YX;4种源苗木各构件的生物量占总生物量比都为叶＞茎＞根.(4)不同种源间苗木各相同构件间的相对生物量结构虽存在差异,但相差不显著(P＞0.05),其中叶相对生物量大小为TH＞SC＞YX＞CY,茎相对生物量为CY＞SC＞TH＞YX,根相对生物量为YX＞CY＞TH＞SC.(5)不同种源间苗木的根冠比大小为YX＞TH＞CY＞SC,但相差不显著(P＞0.05).     

猪主要组织相容性抗原复合物Ⅲ类区域基因研究进展

根据国内外最新资料对猪MHC Ⅲ类区域的基因及功能、物理图谱等方面进行了综述,以期对猪MHC Ⅲ类基因的研究提供最新学术动态。     

英语专业写作中“学习性评价”教师书面反馈的实证研究

教师书面反馈是写作教学的重要组成部分。本研究试图在写作教学中通过＂学习性评价＂教师反馈,并在教学实验前后对教师和学生进行问卷调查和访谈等方式,实现＂以写促学＂的目的,结果表明,教师书面反馈可以提高学生作文水平,帮助学习者正确认识和综合评价自身语言技能,促进整个二语习得进程。     

9个阔叶树种叶绿素估测模型

为了方便快速准确地测量树木叶片的叶绿素质量分数, 对9个阔叶树种的叶片采样, 利用CCM-200测得的叶绿素指数(CCI值)和叶片厚度因子建立叶绿素的估算模型, 将估算结果与萃取法测量叶绿素质量分数比较, 分析发现:仅利用CCM-200测得的叶绿素指数估算叶绿素a, 叶绿素b和总叶绿素质量分数的线性模型误差较大, 叶绿素指数与叶绿素a, 叶绿素b和总叶绿素质量分数的决定系数(R2)均在0.610左右, 相关性不是很显著。当用比叶质量(SLW)来反映叶片厚度, 与叶绿素指数一起作为自变量, 分别建立估算叶绿素a, 叶绿素b以及总叶绿素质量分数的线性回归方程, 发现叶绿素指数及比叶质量与叶绿素a, 叶绿素b和总叶绿素质量分数之间的决定系数(R2)分别为0.678, 0.707和0.689, 相关性得到较大提高。而如果采用比叶面积(SLA), 即比叶质量的倒数来反映叶片厚度, 与叶绿素指数一起作为自变量, 分别建立估算叶绿素a, 叶绿素b以及总叶绿素质量分数的线性回归方程, 各决定系数分别为0.869, 0.893和0.881, 相关性得到显著提高。由此得到结论:利用叶绿素指数与比叶面积建立的叶绿素质量分数估算模型精度较高, 且适用于多种不同树种叶绿素质量分数估算, 具有普适性。     

农科学生英语课堂上的母语依赖分析

从教育心理学和二语习得学科的角度,结合问卷调查,分析农科学生在英语课堂上母语依赖的客观存在性及其发挥的作用。研究表明,农科学生在英语课堂上的母语依赖是客观存在的,母语依赖发挥着缓解学习者心理焦虑,提高学习动机和增强对比意识等作用。     

Perennial O. sativa × O. rufipogon interspecific hybrids: I. Photosynthetic characteristics and their inheritance

A survey of 24 wild Oryza accessions identified Oryza australiensis and Oryza rufipogon as potential sources of enhanced photosynthetic rate for introgression into cultivated rice. Photosynthetic capacity per unit leaf area (CER) was associated with leaf N content but not with leaf chlorophyll concentration, flag leaf area, or specific leaf area. Eight fertile, perennial F₁ hybrids between O. sativa and O. rufipogon were grown in non-flooded soil, and CER was measured at flowering under saturating light. Two F₁ hybrids had greater CER than the average of 26.1 μmol m² s⁻¹. The F₂ progeny from these hybrids were screened for CER in the field, and segregants with even greater rates of photosynthesis were selected. The basis of high photosynthetic rate in the F₂ populations was not leaf thickness or leaf chlorophyll content. One F₂ line had exceptionally high CER and stomatal conductance. Broad-sense heritability on an individual plant basis for CER in two F₂ populations was 0.44 and 0.37. A highly significant offspring-parent regression of 0.89 for CER was observed in a replicated field evaluation (four blocks, five plants per plot) of 20 vegetatively propagated F₂ selections and their F₃ seedling progeny. Broad-sense heritability for CER on a plot-mean basis was estimated as 0.74 for both selected F_2:3 families and for the selected F₂ clones. Genetic resources in the genus Oryza may represent a source of alleles to increase leaf photosynthetic rate in the cultivated species, which we have demonstrated to be a heritable, though environmentally variable, trait in an O. sativa/O. rufipogon population.