黄淮海平原玉米施氮量对后茬小麦土壤剖面硝态氮和产量的影响

在冬小麦-夏玉米一年两熟模式下,玉米品种“郑单958”（植株密度9株/m^2）和小麦品种“93-9”（基本苗704株/m^2）,冬小麦基施144kg N/hm^2,研究了玉米5个施N量（0、90、180、270和360kg/hm^2）对后茬小麦期间土壤剖面硝态氮含量、无机氮总量,以及小麦氮素吸收利用和产量的影响.结果表明：（1）与不施氮相比,玉米施氮显著增加小麦季0～200cm土壤硝态氮含量;自拔节起,0～40cm、0～130cm和0～200cm硝态氮含量均随施氮量增加而递增,在硝态氮含量较高的小区增幅也大.（2）轮作一周期后,不施氮和施氮360kg/hm^2显著影响0～130cm和0～200cm无机氮总量,但在90～270 kg/hm^2之间,施氮量的影响不明显.（3）施氮小于180kg/hm^2时,成熟期小麦植株氮素和籽粒氮素积累量、氮肥利用率均随施氮量增加而递增,但不明显.（4）与不施氮相比,施氮90kg/hm^2的小麦产量和麦玉轮作总产均增加但不明显,施氮180 kg/hm^2均显著增加,施氮270kg/hm^2与180kg/hm^2无明显差异.本试验条件下,夏玉米施氮90～180 kg/hm^2是适宜的.     

小麦花后弱光引起籽粒淀粉的粒度分布及组分含量的变化

在籽粒灌浆阶段(花后1～30 d)对小麦进行光强为自然光照45%的弱光处理,研究了小麦籽粒淀粉粒度分布和组分含量的变化.结果表明,小麦籽粒淀粉粒体积分布呈双峰曲线,峰值分别在5.1～6.1 μm和20.7～24.9 μm,两峰值间的低谷出现在9.9 μm左右.表面积分布和数目分布分别表现为双峰和单峰曲线.小麦花后弱光显著降低2.8～9.9 μm淀粉粒体积百分比,增加22.8～42.8 μm淀粉粒体积百分比.同时花后弱光显著降低<0.8 μm和2.8～9.8 μm淀粉粒表面积百分比,增加0.8～2.8 μm和>9.9 μm淀粉粒表面积百分比.可见灌浆期弱光显著降低籽粒B型(＜9.9 μm)淀粉粒体积和表面积百分比,而A型(＞9.9 μm)淀粉粒比例相对增加.与A型淀粉粒相比,B型淀粉粒对弱光的反映更敏感.小麦弱光处理籽粒淀粉及其组分含量显著低于对照,但其直/支比较对照高.相关分析表明,籽粒直/支比与2.8～9.9 μm淀粉粒体积百分比呈显著负相关,而与22.8～42.8 μm淀粉粒体积百分比呈显著正相关.花后不同阶段弱光显著增加A型淀粉粒体积百分比、降低B型淀粉粒体积百分比,其中灌浆中、后期弱光影响程度较前期大.表明,弱光条件下小麦籽粒淀粉合成底物优先供应淀粉粒的生长,而非形成更多的淀粉粒.     

The cellular pathway of photosynthate transfer in the developing wheat grain. I. Delineation of a potential transfer pathway using fluorescent dyes

A potential cellular pathway for photosynthate transfer between the crease phloem and the starchy endosperm of the developing wheat grain has been delineated using fluorescent dyes. Membrane permeable and impermeable dyes have been introduced into the grain through the crease phloem, the endosperm cavity or the dorsal surface of the starchy endosperm. The movement of the symplastic tracer 5-(6)-6-carboxyfluorescein (CF) derived from 5-(6)-6-carboxyfluorescein diacetate (CFDA), from either direction between the crease phloem and the endosperm cavity, indicated that the symplastic pathway was operative from the crease phloem to the nucellar projection. Furthermore, the inward movement of apoplastic tracer trisodium, 3-hydroxy-5,8,10-pyrentrisulphonate (PTS) from the endosperm cavity and that of CF following plasmolysis showed that there was a high resistance to solute transfer within the apoplast of the pigment strand. All dyes entered the modified aleurone and adjacent sub-aleurone bordering the endosperm cavity. Subsequent movement of the symplastic tracers CF and sulphorhodamine G (SRG) into and through the endosperm was rapid. However, the movement of apoplastic tracers PTS and Calcofluor White (CFW) was relatively slow and with tissue plasmolysis, CF was confined to the cytoplasm of the modified aleurone and subaleurone cells. Together, these results demonstrate that there is a high resistance to solute movement within the apoplast of the cells bordering the endosperm cavity. We propose that photosynthate transfer is via the symplast to the nucellar projection where membrane exchange to the endosperm cavity occurs. Uptake from the cavity is by the modified aleurone and small endosperm cells prior to transfer through the symplast to and through the starchy endosperm.     

THINOPYRUM BESSARABICUM和THINO-PYRUM ELONGATUM的基因组关系研究

对 2个八倍体 C.S- Thinopyrum bessarabicum( AABBDDJJ,2 n=8x=56)和 Goshawk( GHK) - Thinopyrum elongatum( AABBDDEE,2 n=8x=56)的根尖细胞染色体进行 C-分带 ,从中分检出 Th.bessarabicum和 Th.elongatum的各自染色体进行核型分析 ,结果表明 :Th.bessarabicum和 Th.elongatum的大多数染色体都具有端带 ,但 Th.bessarabicum的端带更强 ,很少有中间带 ;而 Th.elongatum的染色体除 E1外其它染色体的端带较弱 ,而且带纹较丰富 ,有较多的中间带。对 C.S- Th.bessarabicum和 GHK- Th.elongatum进行有性杂交 ,其杂交种F1的 PMC染色体在 MI的平均配对构型为 1 5.50 5.0 3 [ 1 4.2 0 ○ 0 .40 0 .2 1 ,其中 Th.bessarabicum和 Th.elongatum染色体平均配对成 2 .5个二价体 ,由 C-分带显示大多数 Th.bessarabicum和 Th.elongatum染色体呈单价体状态。因此推断 ,Th.bessarabicum和 Th.elongatum两物种的染色体应属不同的染色体组     

不同小麦品种氮效率与氮吸收对氮素供应的响应及生理机制

以具有典型特征的不同氮效率小麦品种为材料,研究了低氮和高氮条件下小麦的生物学性状、生理参数和氮同化代谢酶活性.结果表明:低氮条件下,不同氮效率小麦品种根系干质量、茎叶干质量、植株氮累积量基本上为氮高效品种>中效品种>低效品种.低氮条件下,氮吸收高效品种（冀97-6360）的根系活跃吸附面积、TTC还原力、叶片硝酸还原酶活性和叶片NO₃^-含量最大;生理高效品种(石新5418)具有较高的叶片亚硝酸还原酶活性和谷氨酰胺合成酶活性,较低的植株全氮含量、叶片NO₃^-含量和硝酸还原酶活性.低氮条件下植株氮利用效率与氮吸收系数显著相关.不同小麦品种在高氮条件下的生物学性状、生理参数和氮同化代谢酶活性与低氮条件下不尽一致.     

Functional analysis of the ver gene using antisense transgenic wheat

The function of ver203 , a gene related to vernalization in winter wheat, was investigated by expression of a complementary DNA as an antisense RNA in transgenic plants. A verc203:gus fusion‐expression plasmid was constructed in pBI221, which contains a CaMV (cauliflower mosaic virus) 35S‐promoter, a gus gene and a nos terminator. The construct was then introduced into the plant by the pollen‐tube pathway. The results showed that heading was strongly inhibited in 6 of 326 vernalized antisense transgenic winter wheat plants, until both the vernalized control winter wheat and sense transgenic plants ripened. The hybridization analysis of DNA, amplification of the insert DNA sequences with PCR, northern blot analysis with double‐ and single‐stranded probes, and detection of GUS activity by X‐gluc assay gave strong positive results. This suggests that the VER203 protein plays an important role in controlling heading and flower development in winter wheat.     

小麦和玉米根系取样位置优化确定及根系分布模拟

为了确定小麦(Triticum aestivum)、玉米(Zea mays)根系的最优取样位置和更准确地模拟根长密度在土壤剖面的分布, 在冬小麦和夏玉米的灌浆后期, 采用根钻法取样, 比较了不同取样位置对根系分布的影响; 采用Gerwitz和Page模型对根长密度的分布进行了模拟。结果表明, 冬小麦行间和行上取样在0-10 cm土层根长密度差异显著, 在10 cm以下土层差异减少。在确定根长密度分布的取样中, 在0-20 cm土层应考虑根长密度分布的空间差异, 即行上密度大于行间密度; 而在20-100 cm土层, 需要考虑行间根长密度大于行上的空间差异; 在1 m以下土层两个位置的差异逐渐消失, 可不考虑空间差异。夏玉米根长密度在上层土壤表现出距离植株不同位置差异显著的特征。植株位置(株上)、距植株10 cm和距植株20 cm位置根长密度在土壤中的分布特征是: 0-10 cm土层3个位置根长密度差异在50%以上, 根长密度大小是株上>距植株10 cm>距植株20 cm; 而在10-30 cm层次, 根长密度表现为距植株10 cm>株上>距植株20 cm, 30-50 cm土层株上位置的根长密度最小, 50 cm以下各位置根长密度差异不明显。对于玉米根系取样, 50 cm以上土层需要考虑根长密度的空间差异, 50 cm以下土层可不考虑。采用Gerwitz和Page模型, 结合华北平原机械化耕作下形成的土壤犁底层变厚及其犁底层容重增加对根系分布的影响, 在模型中加入土壤容重参数订正可以使模型更准确地模拟根长密度在土壤剖面的分布。     

覆膜栽培下春小麦种群的生长冗余与个体大小不整齐性的关系

 增加有效分蘖数被认为是提高小麦(Triticum aestivum)产量的重要方法之一,但是小麦种群在生长进程中也会形成大量的无效分蘖,存在“生长冗余”。研究了覆膜栽培对两个春小麦种群中无效分蘖比率和收获指数的影响,并从植物个体大小不整齐性和生活史策略的种群生态学角度探讨其影响机制。与露地对照相比,覆膜栽培能显著提高春小麦产量(+38.5%);产量的提高源于地上部分生物量（+44.7%）的显著增加。但是, 覆膜种群的繁殖分配（穗重/地上部分生物量,-5.2%）和收获指数(-4.5%)显著降低;在几个主要生     

Identification and Preliminary Analysis of Several Centromere-associated Bacterial Artificial Chromosome Clones from a Diploid Wheat Library

Although the centromeres of some plants have been investlgated prevlously, our knowledge of the wheat centromere Is still very llmlted. To understand the structure and functlon of the wheat centromere, we used two centromeric repeats （RCS1 and CCS1-5ab） to obtain some centromere-assoclated bacterial artificial chromosome （BAC） clones in 32 RCS1-related BAC clones that had been screened out from a diploid wheat （Triticum boeoticum Boiss.; 2n=2x=14） BAC library. Southern hybridization results indicated that, of the 32 candidates, there were 28 RCS1-positive clones. Based on gel blot patterns, the frequency of RCS1 was approximately one copy every 69.4 kb in these 28 RCS1-positive BAC clones. More bands were detected when the same filter was probed with CCS1-5ab. Furthermore, the CCS1 bands covered all the bands detected by RCS1, which suggests that some CCS1 repeats were distributed together with RCS1. The frequency of CCS1 families was once every 35.8 kb, nearly twice that of RCS1. Fluorescence in situ hybridization （FISH） analysis Indicated that the five BAC clones containing RCS1 and CCS1 sequences all detected signals at the centromerlc regions in hexaplold wheat, but the signal intensities on the A-genome chromosomes were stronger than those on the B- and/or Dgenome chromosomes. The FISH analysis among nine Triticeae cereals indicated that there were A-genomespecific （or rich） sequences dispersing on chromosome arms in the BAC clone TbBACS. In addition, at the interphase cells, the centromeres of diploid species usually clustered at one pole and formed a ring-like allocation In the period before metaphase.     

冬小麦不同生育期最小冠层阻力的估算

作物最小冠层阻力是研究农田蒸发和作物缺水的一个重要参数。使用作物的冠层红外温度信息,将作物在充分灌溉情况下冠层温度与空气温度之差与空气的饱和水汽压差的经验关系同其理论解释相结合,通过实验数据,估算了在华北平原气候条件下的冬小麦（Triticum aestivum L.）的平均最小冠层阻力,为基于这种阻力的应用共基础,研究表明冬小麦最小冠层阻力随发育期而不同,并且抽穗前后差异明显,给出了冬小麦不同生育阶段的平均最小冠层阻力。