Contribution of contrasting plant hierarchies to the response to N fertilizer in maize

The typical size structuring process that occurs as a consequence of intra-specific competition in maize promotes the appearance of contrasting plant hierarchies (i.e. dominated and dominant individuals). This process may become more intense under low nitrogen (N) availability. The alleviation of plant competition by N addition may reduce plant yield variability through a differential response to N in individuals of contrasting hierarchies. In this work, the response to N of dominated and dominant plants from stands with contrasting N supply (0 to 140-200 kg N ha⁻¹) was examined on 11 experiments carried out in Paraná, Argentina (31°50′S; 60°31′W) in a broad range of growing conditions that included the variation of the year, genotype, plant population and sowing date. Our objectives were: (i) to evaluate the response to N in contrasting plant hierarchies of maize, (ii) to quantify the contribution of dominated and dominant plants to the response to N of the overall stand, and (iii) to study the effect of N on relationships between plant hierarchies and stand variability. Response to N of yield per plant was associated with biomass per plant in non-fertilized controls, tending to be higher in plants with low biomass. The response to N of yield per unit area (i.e., considering all individuals of the stand) was related to the response to N of dominant and dominated plants (P < 0.0001). However, at a higher level of response to N of grain yield per unit area (>50-60%), dominant plants had a considerable lower response than dominated plants, whereas at a lower level of response (<30%), the contribution of contrasting plant hierarchies was similar. In stands with similar plant biomass between hierarchies, the differences in the response to N between plant types tended to be negligible. The coefficient of variation of yield per plant was reduced (P < 0.05) by effect of N in 4 out of 11 experiments, although it tended to be consistently lower in fertilized treatments. When the differences between the biomass of dominated and dominant plants were ample we found the highest response to N at the stand level, as a result of the higher increase in grain yield per plant in dominated plants than in dominant ones. The response to N in each plant hierarchy was differentially associated with increases in shoot biomass, harvest index, kernel number per plant and kernel weight.     

植物生长调节剂要要多效唑在草坪草上的应用进展

从多效唑的作用机理出发,分析其对草坪草的作用,概述多效唑在草坪草上的应用效果,指出存在的问题,并展望其应用前景。     

黄秋葵施肥研究进展

概述了黄秋葵的食用、药用价值,栽培特性以及氮磷钾肥、生物肥料、微量元素肥料对黄秋葵的影响,并对黄秋葵高产栽培技术提出了展望。     

Reaction to late blight in response to nitrogen management in Argentine potato cultivars

The objective of this study was to evaluate the reaction to late blight of two potato cultivars in response to nitrogen (N) management under field and in Vitro conditions. In Balcarce trial a reduction in phenols with the addition of excess N was found. Despite the reduction of the concentration of phenols no differences in the relative area under disease progress curve (rAUDPC) were observed between N levels. In Tafí del Valle, the rAUDPC denoted an interaction between cultivar and N level. In Frital, the N0 showed lower rAUDPC than N optimal (Opt) and N excessive (Exc) treatments. In contrast, no differences in rAUDPC between N levels on Pampeana were found. In the detached leaf test, no significant differences between N levels were observed in the threshold of severity of disease and the lesion growth rate. In conclusion, excessive N fertilization did not increase the susceptibility to late blight in this study.     

Resistance of potato to cucumber mosaic virus appears related to localization in inoculated leaves

Although CMV can cause extensive damage to solanaceous crops like tomato, tobacco and pepper, it has little if any impact on the related crop, potato. To better understand this phenomenon, we have tested 32 potato genotypes for susceptibility or resistance to local and systemic Fny-CMV infection. Using ELISA, all genotypes appeared to show virus replication in leaves that were mechanically inoculated. In contrast, only ten genotypes exhibited systemic spread as expressed by significant CMV titers in new growth. These data suggest that, although CMV can replicate in potato cells and appears to spread short distances cell-to-cell, long distance movement appears to be blocked in most potato genotypes. Therefore, the general resistance of potato crops to CMV infection may be related to virus localization at points of entry.     

水稻幼穗响应稻曲病菌毒素胁迫早期的转录组分析

【目的】由稻曲病菌引起的稻曲病不仅造成水稻减产,而且还会产生对动物和植物有毒的真菌毒素。探明水稻幼穗对稻曲病菌毒素胁迫响应的分子机制,可为发掘水稻抗稻曲病基因以及抗病分子育种开辟新的思路。【方法】用稻曲病菌毒素处理水稻幼穗,采用转录组测序技术对水稻幼穗进行转录组测序,以水稻9311基因组作为参考基因组进行对比,利用TPM法计算基因表达量,设定参数（差异倍数的绝对值不小于2,且q值不大于0.05）筛选差异表达基因。结合基因差异表达分析、富集功能分析,鉴定水稻响应胁迫的关键基因,并利用实时荧光定量PCR技术对差异表达基因进行验证。【结果】在稻曲病菌毒素胁迫12 h后,水稻幼穗出现2526个差异表达基因（DEG）;通过GO富集、KEGG代谢途经和KOG功能分析,将差异基因划分为GO功能下的64个条目、32个代谢途径和KOG功能下23个类别,包括淀粉和蔗糖代谢、苯丙类生物合成、碳代谢、糖酵解/糖异生、氨基糖和核苷酸糖代谢等生物学过程。DEG中有66个植物转录因子,分属7种植物转录因子家族,包括WRKY和Myb两大转录因子。分析二萜类生物合成与淀粉和蔗糖代谢途径相关基因发现,OsCPS2、OsKSL4和细胞色素P450等基因表达量上调,而淀粉酶、β-呋喃果糖苷酶和UDP-焦磷酸化酶等基因表达量下调,推测这些基因在水稻响应稻曲病菌毒素胁迫时发挥重要的作用。【结论】稻曲病菌毒素作为非生物胁迫因素对水稻幼穗具有毒性;通过干扰淀粉和蔗糖代谢等途径而影响种子营养物质的合成,降低水稻抵抗病原菌侵染水稻的能力。     

Effects of fertilizer application to grasslands in Greece

Grasslands in Greece are composed of a large variety of plant species, but they have relatively low productivity due to their misuse by domestic animals for thousands of years, and also to soil and climatic factors. Fertilizer application can improve productivity by affecting herbage yield, botanical composition, earliness of spring growth and quality. The application of N and P generally alters species composition and increases dry matter and crude protein yields, while the addition of K is often not effective. Also, NP fertilizer increases the in vitro digestibility while N often decreases P, Ca, Mg and Zn contents of herbage. It appears that Greek grasslands cannot utilize as much N as their temperate counterparts and that their soils are usually deficient in P. This indicates that NP fertilizer is necessary to secure increased yields with P being important in achieving a balanced grass-legume composition in the plant cover.     

不同冬小麦基因型对钾肥敏感性差异的研究

采用不同的小麦基因型,以４水平钾浓度的水培方法进行研究。在高钾条件下,小麦不同基因型的干重、植株含钾量、吸钾量、根系状况差异较小。随着钾浓度的下降,小麦不同基因型的干重、植株含钾量、吸钾量、根系状况差异逐渐加大。对钾肥反应敏感的小麦基因型,随着钾浓度的降低,缺钾症状加重。因而筛选出晋麦３１号为耐低钾基因型。     

玉米抗倒伏性评价方法的研究

选定抗倒性不同的10个玉米品种,对现有玉米抗倒伏研究方法进行比较研究,探索玉米抗倒伏综合评价方法。相关分析结果表明,倒伏系数是株高、单茎鲜重、茎秆机械强度和根量的综合体现,倒伏系数与倒伏程度的相关性达到极显著水平。通径分析表明,茎秆机械强度和根量对玉米倒伏系数有较大负作用,单茎鲜重和株高对倒伏系数的直接和间接的效应都较小。聚类分析将10个品种划分为5个倒伏级别。以倒伏系数为评价标准,能客观准确地反映10个玉米品种的抗倒性,抗倒性强的品种倒伏系数较小,依据倒伏系数可以建立玉米抗倒等级划分标准。     

Properties of Short-Dough Biscuits in Relation to Structure

The mechanical properties of short-dough biscuits of various composition were determined in three-point bending tests. The temperature during dough preparation and the dough water content affected the air volume fraction and the mechanical properties to an extent which depended on the fat content. These results suggest that the air volume fraction of the biscuits is likely to be related to the rheological properties of the doughs. The temperature at which measurements were made affected the mechanical properties of the biscuits, especially at higher fat contents. The diffusion of Sudan III into the biscuits also depended on the fat content. The mechanical properties were markedly influenced by water content; as a result of the plasticising effect of water, the matrix underwent a glass transition. The effect of sugar type on mechanical properties depended on the type of biscuit. It is concluded that low-fat biscuits are fat-dispersed systems and that high-fat biscuits are bicontinuous. Whether biscuits are in a glassy or rubbery state cannot be predicted from their water contents in relation to the state diagrams of either gluten or sucrose.     

水稻热耗散对逆境的响应

非光化学猝灭(NPQ)常用于评估以热能途径耗散的光能(热耗散),热耗散在维持光能转化平衡中起着重要作用,是水稻叶片重要的光防御机制。大量研究表明,热耗散的诱导受跨类囊体膜ΔpH、叶黄素循环和PsbS蛋白等的调控;NPQ与光保护效应不呈线性关系,只有在某些特定条件下,NPQ才可作为光保护效应的有效指标;在高温、低温、缺氮、干旱、盐胁迫等逆境下水稻NPQ显著增加,热耗散可能与水稻抗逆性密切相关。本文从热耗散的诱导和调控机制、NPQ与光保护效应以及水稻NPQ对环境因子(温度、氮营养、水分、盐)的响应等4个方面综述了水稻叶片热耗散的研究进展,并对水稻NPQ与抗逆性关系的研究作了展望。     

甘蔗对螟虫抗性的初步鉴定

在田间自然条件下,在分蘖期、拔节期和成熟期分别对热引1号、热引2号和ROC22号进行虫害调查。对分蘖期枯心率、拔节期和成熟期虫蛀孔数的结果分析表明,在3个不同生长时期,这3个甘蔗材料间对螟虫的抗性均差异显著,抗性依次为热引1号、ROC22、热引2号。因此,与当前主栽品种ROC22相比,热引1号可作为选育抗螟虫甘蔗品种的优良亲本,为抗螟虫甘蔗品种的选育提供良好基础材料。     

黑龙江省马铃薯晚疫病菌对甲霜灵药剂的敏感性测定

利用菌落直径法对2008年黑龙江省4个地区53株马铃薯晚疫病菌的甲霜灵药剂敏感性进行了研究,结果表明,黑龙江省马铃薯晚疫病菌中对甲霜灵药剂具有抗药性的菌株占很大比重,但是区域间抗药菌株的出现频率具有很大差异,其中牡丹江、哈尔滨地区抗药菌株达到了100%,海伦的抗药菌株为23.08%,加格达奇没有出现抗药菌株。本研究对在黑龙江省科学合理地使用苯基酰胺类杀菌剂防治马铃薯晚疫病具有重要意义。     

茶皂素在农药上的应用研究概况

本文从茶皂素对有害生物的生物活性及其对农药的增效作用等方面阐述了茶皂素的研究进展,并就茶皂素的生物活性和增效作用机制进行了初步探讨。     

花生对根结线虫病抗性温室快速鉴定方法

为了通过对花生抗线虫鉴定方法的比较,确定更加快速有效的抗性鉴定技术,作者于2002～2003年在佐治亚大学的Tifton试验站进行了温室盆栽试验.结果表明侵然期幼虫(2000～4000条/株)与虫卵(8000～16000粒/株)均可以用于花生抗线性鉴定的温室接种,但与使用虫卵接种相比,以侵染期幼虫作为接种体需要多花3～5d的时间收集幼虫;接种后14d,可以依据0～5级的虫瘿分级标准将供试的4份花生种质区分开来;接种后6～10周依据卵块数量或每克根中的虫卵数可以进一步确认花生的抗性水平.虫瘿级数、虫瘿数量、卵块数量及每克根中的卵量之间存在着极显著(P＜0.01)的正相关关系.根据研究结果提出了温室中花生抗线虫鉴定的程序方法以8000粒卵/株为适宜接种量,接种后14d依据0～5级的虫瘿分级标准进行初筛,对初筛入选的材料再在接种后6周根据卵块数量或卵量验证其抗性.     

花生基因型耐铝性生物学标定

根据植物耐铝性与其遗传的关系,在花生生态分类学四大类型中,选取40个不同基因型花生,通过组合式溶液培养试验、上培试验和田间试验,结果表明：（1）不同耐铝性花生品种具有不同的生物学特征,在根色、根形、根长、根系体积、植株生长量、叶色、叶形和荚果等具有明显差异;在植物细胞排列、细胞壁厚度、细胞形状以及细胞内的变化等也具有明显差异。（2）通过生物学标定,选择6个典型花生品种划分为高耐、中耐和敏感型三种耐铝基因型。（3）三种耐铝基因型在铅胁迫下,其浓度与花生主根长度、主根生长速率、根系体积、植株生长量和荚果发育量呈极显著负相关,其相关绝对值是敏感型＞中耐型＞高耐型。（4）三种耐铝基因型在溶液培养条件下,铝胁迫临介值分别为5．9、2．9和1．1mg／L,而在土培条件下,铝胁迫临界值（交换性铝饱和度）分别为12％、6％和1％左右。     

水稻白叶枯病的抗性遗传研究

 以4个晚粳品种为材料，采用双亲本回交设计对白叶枯病抗性的遗传特性及基因效应作了分析。参试的晚粳品种对两个菌系KS-6-6和浙173的抗性是不完全隐性遗传，符合加性－显性模型；基因的加性效应为极显著，显性效应和上位性效应则皆不显著。加性变异和显性变异并存，但以加性遗传变异为主，表现具有较高的广义、狭义遗传率。菌系Ⅱ与Ⅳ的病级间的关联性表明，晚粳品种嘉23对白叶枯病两菌系的抗性属同一多基因系控制的不完全隐性的数量性状遗传；从有效因子数目估值来看，本研究参试材料至少有一对隐性抗病基因在起作用。     

向日葵抗列当遗传研究

从吉林省境内采集的向日葵材料中鉴定筛选出了对列当抗感性无分离的亲本,配制了3个抗列当( P1 ) ×感列当( P2 )的组合。通过对3个组合F1、F2 和BC1 ( P2 )的列当接种鉴定,后代的表现型符合一对显性等位基因 控制的分离比率。根据抗列当的遗传规律,提出了感列当杂交种和自交系的抗性改良方法。