红姬凤梨离体培养植株再生关键技术研究

[目的]建立红姬凤梨组织培养快繁体系。[方法]以MS培养基为基本培养基添加植物生长调节剂,对红姬凤梨叶片进行愈伤组织诱导,并进行芽分化、芽的继代增殖和生根培养。[结果]叶鞘愈伤组织诱导以MS＋2,4-D0．5mg／L＋BA3．0mg／L＋KT2．0mg／L培养基最好、愈伤组织诱导率和分化率分别达82．4％和40．2％;丛生芽诱导以MS＋2,4-D0．2MG/L＋NAA0．05mg／L＋BA3．0mg／L＋KT2．0mg／L培养基增殖效果最佳,增殖倍数迭9．72;生根诱导以1／2MS＋NAA3．0mg/L培养基诱导生根效果最好,平均每株生根12．12条。[结论]采用组织培养可有效去除病毒,增加繁殖系数。     

苹果杂种F1代叶片性状分离及早期选择研究

为了探讨叶片性状在苹果杂交实生后代早期预先选择中的可行性和实用性,2007～2008年连续两年对秦冠×富士﹑富士×秦冠杂交F1代的572株实生苗的叶片大小、叶长、叶宽、叶形指数、叶柄长度、叶柄粗度和叶片厚度等7个叶片性状指标进行了调查测定和统计分析.结果表明,苹果叶片性状在杂交后代中存在广泛性变异,其中叶片大小在个体间的差异变化最大;杂交后代群体中,叶片大小变化呈连续性正态分布,其中小叶型植株所占比率为8.97%～11.03%;3年生与4年生杂交苗的叶片性状表现基本一致,能反映叶片性状特征,可以作为叶片性状早期选择的开始年限;苹果杂种F1代实生苗叶片大小变异系数大,田间调查测定简便、易行,可以作为苹果"大群体"杂交后代叶片性状早期选择的有效指标.     

辣椒叶片总RNA提取与质量分析

用3种不同方法提取辣椒叶片的总RNA,研究辣椒叶龄和基因型对总RNA提取的影响和筛选辣椒总RNA提取的最佳方法.结果表明,方法2为辣椒叶片总RNA提取的最佳方法;从新叶中提取的总RNA的亮度高,完整性最好,中龄叶次之,老叶最差;辣椒材料0860-1总RNA的28 S和18 S条带明亮,质量浓度最高,材料0876和08122的这些条带较暗,质量浓度低.     

北京地区棚栽台湾青枣叶片性状对比研究

以北京地区大棚栽植的台湾青枣9个品种的叶片为材料,分别对其表型进行观察对比,对其叶面积、叶绿素含量等指标进行测定分析,并利用石蜡切片技术对显微性状进行观察对比,研究了不同品种间叶片性状差异。结果表明:北京地区棚栽台湾青枣各个品种间叶片性状表现差异显著,但部分品种内指标间表现并不一致,为北京地区台湾青枣的引种栽培提供了一定依据。     

绿豆开花后不同节位叶片衰老的超微结构研究

以绿豆品种安05-4为试验材料,在透射电镜下观察了绿豆不同生育时期、不同节位叶片衰老进程.结果表明,绿豆植株开花后16 d内,叶肉细胞排列整齐,细胞间隙小,细胞中叶绿体高基粒片层数增加;开花23 d以后,叶片迅速衰老,细胞解体,叶肉细胞出现间隙,叶绿体减少,叶绿体基粒片层、基质片层解体.不同节位叶片衰老存在差异,表现为主茎开花第三节叶片＞第二节叶片＞第一节叶片.     

Modeling responses of dryland spring triticale,proso millet and foxtail millet to initial soil water in the High Plains

Dryland farming strategies in the High Plains must make efficient use of limited and variable precipitation and stored water in the soil profile for stable and sustainable farm productivity. Current research efforts focus on replacing summer fallow in the region with more profitable and environmentally sustainable spring and summer crops. In the absence of reliable precipitation forecasts for the crop growing season, farmers rely mainly upon knowledge of plant available water (PAW) in the soil profile at planting for making crop choice decisions. To develop a decision support strategy for crop selection based on initial PAW, experiments were conducted with spring triticale (XTiticosecale Wittmack), proso millet (Panicum miliaceum L.), and foxtail millet (Setaria italica L. Beauv.) under artificially controlled Low, Medium, and High initial PAW levels during 2004 and 2005 at Akron, Colorado, and Sidney, Nebraska. The objectives of this study were to adapt an existing cropping systems model for the simulation of triticale and millet and to evaluate simulations from the adapted model by comparing results with field data collected under varying initial PAW conditions. The Root Zone Water Quality Model with DSSAT v4.0 crop growth modules (RZWQM2) was used. Specifically, the Cropping System Model (CSM)–CERES–Wheat module was adapted for simulating triticale, and CSM–CERES–Sorghum (v4.0) module was adapted for simulating proso millet and foxtail millet. Soil water, leaf area index, grain yield, and biomass data for the highest PAW treatment from one crop season for each of the three crops were used to adapt and calibrate the crop modules. The models were then evaluated with data from the remaining PAW treatments. The proso millet module was further tested with four years of data from a crop rotation experiment at Akron from 2003 to 2006. Simulation results indicated that the adapted and calibrated crop modules have the potential to simulate these new crops under a range of varying water availability conditions. Consequently, these models can aid in the development of decision support tools for the season-to-season management of these summer fallow replacement crops under dryland conditions in semi-arid environments.     

Yield losses of soybean and maize by competition with interseeded cover crops and weeds in organic-based cropping systems

Weed management is a major issue in organic farming systems. Although interseeding cover crops is one alternative to herbicides, cover crops often suppress not only weeds but also main crops. Therefore, using cover crops for weed control without adverse effects on main crop growth is important. To verify the effect of cover crops on competition between main crops, cover crops and weeds in a snowy-cold region, main crops soybean (Glycine max Merr.) in 2005 and maize (Zea mays L.) in 2006 were grown with cover crops winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), respectively. The cover crops were sown on three sowing dates: before main crop planting (Pre-MC), on the same date of main crop planting (Syn-MC) and after main crop planting (Post-MC). A plot without cover crops (Sole-MC) was used as a control. The dry weight (DW), vegetation cover ratio (VCR), vertical community structure and chlorophyll content were measured to estimate the competition between main crops, cover crops and weeds. Weed DW was suppressed significantly by sowing cover crops in both soybean and maize. This weed suppression was associated with the increase of VCR of main crops plus cover crops at the early growth stage of main crops. Soil seed banks of dominant weed also became lower by sowing cover crops, implying the importance of proper weed management for suppressing weeds successively. In addition, the sowing dates of cover crops had large effects on main crops DW especially in maize, i.e., it was significantly lower in Pre-MC and Syn-MC than in Post-MC. Although the cover crop height was markedly shorter than the main crop height, the chlorophyll content of the main crops was significantly lower when cover crops were sown earlier. These results suggest that the growth inhibition of main crops by cover crops was partly caused by competition for nutrients between main crops and cover crops, and this growth inhibition was alleviated when cover crops were sown after the establishment of main crops. Consequently, soybean yield was the highest in Post-MC and decreased by 29%, 18% and 7% in Sole-MC, Pre-MC and Syn-MC, respectively, and maize yield was also the highest in Post-MC and decreased by 68%, 100% and 24% in Sole-MC, Pre-MC and Syn-MC, respectively. It was concluded that weeds could be controlled effectively by sowing cover crops after planting main crops in organic farming systems in a snowy-cold region.     

氮素对小麦不同叶位叶片叶绿素荧光参数的调控效应

为了解氮素对小麦不同叶位叶片光合能量利用的影响,测定和分析了旱地和水地小麦品种在3个氮素水平下不同叶位叶片的叶绿素荧光参数.结果表明,随氮素水平的提高,小麦幼苗叶片最大荧光(Fm)、可变荧光(Fv)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ潜在活性(Fv/Fo)和非光化学猝灭系数(qN)都呈上升趋势,而光化学猝灭系数(qP)则呈下降趋势;但旱地品种叶片荧光参数对氮素更敏感,旱地品种小麦幼苗叶片的Fm、Fv、 Fv/Fm、Fv/Fo和qN均高于水地品种,qP低于水地品种.旱地和水地品种在不同氮素处理下各叶位叶绿素荧光参数表现不同,光合能量利用随叶位的降低逐渐升高.     

Responses of rice leaf thickness,SPAD readings and chlorophyll a/b ratios to different nitrogen supply rates in paddy field

The objective of this paper was to investigate the influence of different nitrogen (N) application rates to some morphological and physiological features of leaf blades, including leaf thickness, chlorophyll content at different leaf ages and chlorophyll a/b ratios. A paddy field and a cement tank experiments were conducted simultaneously. Rice leaf thickness was measured through a specially developed displacement sensor. Meanwhile, chlorophyll content was estimated using chlorophyll meter (SPAD) and spectrophotometer after ethanol extraction of leaf samples. With the increase of N application, leaf thickness became thinner and chlorophyll a/b ratios decreased. Moreover, the sensitivity of the SPAD readings of the same leaf at different leaf ages to N rates was assessed through coefficients of variation (CV). CV of SPAD readings increased from 8.8% to 21.6% during leaf lifetime, which indicates that SPAD readings became more and more sensitive to nitrogen rates as leaf aged. Therefore, SPAD readings of the lower leaves, which were physiologically older than the upper ones, were more sensitive to nitrogen rates.     

水分胁迫对不同基因型夏大豆冠层发育及耗水量的影响

在防雨棚条件下研究了不同阶段水分胁迫对4个夏大豆品种五星3号、冀豆15、冀豆16和冀豆17冠层发育和耗水特性影响.结果表明:大豆耗水规律为出苗后20 d内日耗水强度较低,初花期～鼓粒初期较高,最高峰出现在初花期前后,鼓粒中后期较低.最大叶面积指数(LAI)出现在盛花期,不同阶段水分胁迫使多数品种的LAI明显下降.从冠层发育角度,冀豆16苗期抗旱性较强,五星3号花期和鼓粒期抗旱性较强,冀豆15鼓粒期抗旱性较强.五星3号、冀豆15和冀豆16的LAI相近,但五星3号的耗水量较低,冀豆17 LAI和耗水量均较高.大豆主要耗水层在0～100 cm,尤其0～50 cm土层土壤水分状况对大豆的生长发育影响效应更大.