磷胁迫下大豆根分泌有机酸的动态变化

通过水培试验采用直接收集法和高效液相色谱技术测定了大豆根分泌物中有机酸的组成和含量,探讨了不同磷处理条件下大豆根分泌物中有机酸的动态变化,分析了不同磷处理对大豆根系生长和根分泌有机酸的影响。结果表明,大豆缺磷时,根冠比和根长密度增加,根直径变小,根分泌物中有机酸特别是苹果酸、柠檬酸和反丁烯二酸的数量增加,缺磷处理苹果酸和顺丁烯二酸的释放高峰先于供磷处理,不同生育时期有机酸分泌量存在明显差异。     

橡胶树红根病的蔓延速度及预测预报

橡胶树红根病菌主要依靠根系接触蔓延传染,其蔓延速度与橡胶树种植密度等有关。依据大田橡胶树发病情况调查,推导出红根病在橡胶树林段中的蔓延速度公式。运用此公式对橡胶树红根病在大田中的蔓延发展进行预测预报,结果与实际情况相似     

控制性分根交替灌水对作物水分利用率的影响及节水效应

控制性分根交替灌溉（ｃｏｎｔｒｏｌｅｄｒｏｏｔｓ－ｄｉｖｉｄｅｄａｌｔｅｒｎａｔｉｖｅｉｒｉｇａｔｉｏｎ,ＣＲＡＩ）是康绍忠提出的一种农田节水调控思路,其基本概念与传统灌水方式有着根本的不同。传统的灌水方法,追求田间作物根系层的充分和均匀湿润,ＣＲＡ...     

Quantity production of anther-derived haploids from a multiple disease resistant tobacco hybrid. I. Frequency of plants with resistance or susceptibility to tobacco mosaic virus (TMV), potato virus Y (PVY), and root knot (RK)

Summary Methods are described for producing large numbers of haploid plantlets from anthers of a flue-cured tobacco hybrid with monogenic resistance to tobacco mosaic virus, (TMV), potato virus Y (PVY) and root knot (RK), respectively. Additional details are given on colchicine treatment for converting haploids to doubled haploids (DH's) and on the frequency of spontaneous DH's among untreated plantlets. Disparate genetic ratios of TMV-resistant to TMV-susceptible plants were obtained among colchicine-treated haploid plantlets, induced DH's and untreated haploids when compared with F₂ and BC₁ progenies. Haploids (gametes) with the gene for TMV resistance occurred more frequently than expected and plantlets with the gene for RK resistance occurred less frequenctly than expected. Transmission of the gene for PVY resistance differed only slightly from Mendelian expectations. These unexpected ratios, in addition to the frequent occurrence of plastid chimeras among anther-derived plantlets, strengthened our conviction that haploidy is somehow associated with mutation.Joint contribution from the Departments of Genetics, Crop Science and Plant Pathology, North Carolina State University, and the Tobacco Research Laboratory, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Oxford, North Carolina. Paper No. 5576 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, North Carolina.     

滑液支原体WVU1853株热不稳定延伸因子的表达及黏附特性分析

旨在探究滑液支原体(Mycoplasma synoviae,MS)热不稳定延伸因子(elongation factor thermo unstable,EF-Tu)的黏附特性.参照GenBank中MS WVU1853株EF-Tu序列,设计引物对Tu-F/Tu-R,利用PCR扩增获得MS EF-Tu基因后,将其克隆入pE...     

低覆盖度行带式种植模式下赤峰杨根系分布特征

采用根钻法对低覆盖度行带式栽植模式下赤峰杨的根长密度的空间分布特征进行了研究,同时用烘干法对其根质量密度进行了测量。结果表明:赤峰杨的总平均根长密度在不同土层间变化很大,0.0 40 cm土层为根系主要分布区域,其在总平均根长密度中所占比例高达77.1%;不同径级之间的根长密度差异显著,0.0 0.2 mm径级根系的根长密度最大,可达0.61 cm·cm-3。带间根长密度变化出现了先增大后减少而后略有增大的趋势,环境因子影响根系分布,>2.0 mm的粗根根长密度主要分布于带间。低覆盖度行带式配置模式下的赤峰杨吸收根系(<2mm)主要分布于0 40 cm深度区域,粗根(>2.0 mm)主要分布于地表40 cm以下区域,带间是根系的主要分布区域,根系主要利用的是天然降水。     

黑龙江春小麦根腐病危害损失研究

 通过田间小区控制试验和大田中取样调查等方法,对小麦根腐病在小麦生长不同阶段的危害损失进行了较详细的研究,明确了小麦根腐病苗腐主要影响田间保苗率、幼苗长势及成穗率等而造成产量损失;成株期的叶腐、穗腐则主要影响粒重而造成大幅度减产;同时穗腐又造成小麦籽粒感病,使种子质量下降而带来损失。     

Soil fertility enhancement by planted tree-fallow species in the humid lowlands of Cameroon

Four shrub/tree species, Alchornea cordifolia, Pennisetum purpureum, Chromolaena odorata, and Calliandra calothyrsus were evaluated for their potential contribution to soil fertility restoration after two years fallow. Standing biomass, root distribution, nutrient content in the biomass, decomposition and nutrient release patterns, and association with mycorrhizae were the evaluation parameters. Alchornea and Pennisetum produced thehighest above-ground biomass, 66 t and 54 t/ha respectively. Pennisetum had more than 19 t/ha of root, 92% of which was in the 20 cm top soil. Alchornea had 74% of it roots in this soil layer, mostly as coarse roots while Calliandra had a deeper root system. Alchornea fallow accumulated more N and Ca, and Pennisetum fallow, more K than others, and mycorrhizae were mostly associated with Alchornea roots. The ranking of the different species for the decomposition rate was: Chromolaena > Pennisetum > Calliandra = Alchornea. Also release of nutrients during decomposition followed the order K > N > Ca. Alchornea and Pennisetum could be recommended as green manure species especially when high quantities of material are needed for weed or erosion control. Calliandra and Chromolaena, because of the flush of nutrient during early mass, loss can be used as mulch when the crop demand of nutrient is high. Alchornea decomposed slowly and therefore could be used to improve Chromolaena mulch, thus contributing to the build up of soil organic N and providing both short- and long-term nutrient release. This revised version was published online in June 2006 with corrections to the Cover Date.     

4个国外引进树种扦插试验初报

采用全光自动喷雾扦插育苗设备,进行欧洲云杉、白云杉、黑云杉、东部白松４个 国外引进成功树种半木质化嫩枝扦插试验,探讨了这４个树种的扦插育苗技术。沙质插壤上各树种生根率分别达欧洲云杉７７．５％、白云杉５２％、黑云杉４４．５％,东部白松在锯末插壤上扦插生根率为３５％。为进一步扩大栽培,加速林木良种化,走有性选择、无性繁育的无性系林业发展道路,提供了新的可行的无性繁殖方法。