景天类和马齿苋类植物耐旱性快速评价方法初探

[目的]建立快速、标准化测定景天类、马齿苋类植物耐旱性的评价方法。[方法]以佛甲草、松叶景天、毛马齿苋为试验对象,比较了它们的叶片结构,研究了人工气候箱模拟高温干旱胁迫对它们形态特征及生理生化指标的影响,并探讨了上述指标对快速评价3种植物抗旱性的有效性。[结果]用人工气候箱模拟干旱胁迫能显著提高3种植物耐旱性的筛选效率,建议以此为基础建立景天类、马齿苋类植物快速评价方法;叶片结构特征和形态变化与水分代谢紧密相关,可作为3种植物耐旱性评价的基本依据;干旱胁迫后,叶绿素和游离脯氨酸含量差异反映了3种植物对干旱胁迫的敏感程度,可作为耐旱性评价的参考;SOD、POD活性与3种植物对干旱的抵抗力不一致,不宜作为耐旱性评价的指标。[结论]综合叶片解剖学、形态变化及复水试验结果,得到耐旱性强弱为毛马齿苋〉佛甲草〉松叶景天。     

Response of spring planted barley (Hordeum vulgare L.), oats (Avena sativa L.) and wheat (Triticum aestivum L.) to mesotrione

There is little information on the response of spring planted barley (Hordeum vulgare L.), oats (Avena sativa L.) and wheat (Triticum aestivum L.) to mesotrione under Ontario environmental conditions. Four field studies were conducted in Ontario, Canada over a two-year period (2008 and 2009) to evaluate the sensitivity of spring planted cereals (barley, oats, and wheat) to pre-emergence (PRE) and post-emergence (POST) applications of mesotrione at 50, 100, and 150 g ai ha⁻¹. Mesotrione applied PRE caused minimal visible injury at 3, 7, 14 and 28 days after emergence (DAE) and had no adverse effect on plant height or yield of barley, oats and wheat. Mesotrione applied POST caused as much 11% injury and reduced plant height as much as 6% in spring planted cereals. Injury was higher in wheat compared to barley or oats. Mesotrione applied POST had no adverse effect on the yield of barley or oats but decreased the yield of wheat as much as 14%. Based on this study, mesotrione applied PRE at 50, 100 or 150 g ai ha⁻¹ can be safely used in spring planted barley, oats, and wheat. Mesotrione applied POST at the proposed dose of 50, 100 or 150 g ai ha⁻¹ can also be safely used in spring planted barley and oats. However, mesotrione applied POST results in unacceptable injury in spring planted wheat.     

根生长法测定柳树对重金属的耐性研究（摘要）

[目的]探讨柳树对单一或复合重金属的耐性大小,为木本植物修复重金属污染土壤提供理论依据。[方法]采用根生长法研究重金属Cu^2＋、Pb^2＋、Zn^2＋及3者混合液对柳树枝条不定根生长的影响。调查项目包括柳树枝条不定根的数目及长度,并由此计算生根率、抑制率和耐性指数。[结果]不同浓度的重金属溶液对柳树枝条不定根的生长存在显著影响。当Cu^2＋浓度高于15mg/L、混合溶液浓度高于20mg/L、Zn^2＋浓度高于30mg/L时,柳树枝条均无不定根生成;溶液浓度达到40mg/L时,只有Pb^2＋处理组能长出不定根;随着溶液浓度的升高,柳树枝条不定根的数目逐渐下降;浓度为5mg/L的Zn^2＋处理组柳树枝条不定根数目最多。其他浓度中,Pb^2＋处理组不定根数目最多、根长及平均根长最长、生根率最高。[结论]柳树枝条对Pb^2＋的耐受性最强,对Cu^2＋的耐受性最弱。柳树对3种重金属及3者混合液的耐受性大小依次为Pb^2＋〉Zn^2＋〉Cu^2＋＋Pb^2＋＋Zn^2＋〉Cu^2＋。     

Mechanisms of resistance in cotton to whitefly (<Emphasis Type="Italic">Bemisia tabaci</Emphasis>): Tolerance

Screen house experiments were conducted under no choice conditions, to determine the tolerance, a mechanism of resistance, in cotton under a population pressure of 150 and 300 pairs of whiteflies Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Twelve cotton genotypes, viz., four resistant (NHH 44, Supriya, LD694 and PA 183), four susceptible (F 846, IS-376/4/1/20/72, LK 861 and RS 2013) and four with moderate reaction (T x Maroon 2-78, MRC 6304Bt, RS 2098 and CNH 911) to B. tabaci were assessed in terms of decrease in plant height, number of nodes and chlorophyll content (a, b and total) from control. The study revealed that all three characters are important to identify tolerance. A strong tolerance mechanism is operating in NHH 44. The genotypes LD 694 and PA 183 were rated as moderately tolerant, however, IS 376/4/1/20/72, Tx Maroon 2-78, MRC 6304Bt, F 846 and CNH 911 exhibited no tolerance mechanism and were categorized as the most susceptible genotypes.     

耐密植大豆品种沈农12叶片性状研究

以耐密植大豆沈农12和普通大豆辽豆11为试材,在不同种植密度(7.5、15.0、22.5、30.0、37.5、45.0万株.hm-2)下,比较了2个品种的叶片性状。结果表明:耐密植品种沈农12叶形指数较高、叶柄较短、叶倾角较小,有利于密植栽培;随着种植密度增加,在一定密度范围内叶形指数、叶柄长度均随密度增加而增大;耐密性不同的品种叶柄长度随密度而增加的幅度不同,沈农12增幅较小;叶倾角也有随密度增加而减小的趋势。沈农12叶片性状有利于叶片的受光态势,因而,该品种的净光合速率较高,并且随着密度增加其叶片的净光合速率下降幅度较小。     

Correlation of ethylene synthesis in Citrus fruits and their susceptibility to Alternaria alternata pv. citri

The susceptibility of Fortune (Citrus clementina × Citrus reticulata), Citrus paradisi and Citrus limon fruits to Alternaria alternata pv. citri was investigated using different artificial inoculation methods. The results obtained reveal that the C. paradisi and C. limon fruits are less susceptible to A. alternata pv. citri than Fortune fruits, although all showed symptoms of Alternaria brown spot when the cuticle was broken and the flavedo or flavedo + albedo was removed. Furthermore, it was seen that susceptibility to the fungus decreased as the age of the fruit increased. There was a positive correlation between the susceptibility of the different Citrus fruits to A. alternata pv. citri and their “in vivo” ethylene levels, the most susceptible fruit (Fortune) producing more ethylene during growth than the less susceptible C. limon and C. paradisi. This suggests that ethylene may well be considered as a possible marker of Citrus fruit susceptibility to A. alternata pv. citri. Disease development increased when the Fortune fruits were treated with 1 mM ACC (a precursor of ethylene biosynthesis) or 1 mM Ethephon (an ethylene-releasing compound) prior to inoculation with A. alternata pv. citri. The role of ethylene as a factor involved in disease development is discussed.     

Polyphosphate kinase is essential for swarming motility, tolerance to environmental stresses, and virulence in Pseudomonas syringae pv. tabaci 6605

Polyphosphate kinase (PPK), encoded by the ppk gene, is a principal enzyme responsible for synthesis of inorganic polyphosphate (poly P) from ATP in many Gram-negative bacteria. In order to elucidate the functions of poly P in Pseudomonas syringae pv. tabaci 6605, an in-frame deletion mutant of the ppk gene (ppk) was constructed. The ppk mutant did not accumulate poly P, whereas the wild-type strain accumulated a large quantity. The mutant had reduced swarming motility, even though it retains swimming motility like the parental strain. The mutant exhibited increased sensitivity to prolonged incubation and environmental stresses, such as heat shock and oxidative stress and reduced exopolysaccharide (EPS) production compared to the wild-type. Northern blot analysis revealed that expression of the rpoS gene, encoding the stationary phase sigma factor RpoS, was reduced in ppk in the logarithmic phase, indicating that rpoS is regulated by the ppk gene. The poly P deficient mutant had significantly reduced ability to cause disease in its host tobacco plant and in planta growth of the mutant was also significantly reduced in host tobacco leaves as compared to the wild-type strain. Thus, our results suggest that poly P plays an important role in the virulence of P. syringae pv. tabaci 6605.     

First frost: Effects of single and repeated freezing events on acclimation in Picea abies and other boreal and temperate conifers

In experiments with needles of Picea abies, we tested the specific hypothesis that a single night of freezing acts as a signal that triggers a rapid increase in low temperature (LT) tolerance, and the more general hypothesis that repeated or prolonged freezing stimulates increased LT acclimation. In three growth chamber experiments involving acclimation under early- to mid-autumn light and temperature conditions followed by one or more freezing treatments, we found no significant effect of a single night of freezing on LT tolerance, and only limited and inconsistent effects of repeated and prolonged freezing. We also tested the effect of prolonged storage at −5 °C on LT tolerance on samples of three boreal and three temperate conifer species during acclimation under field conditions, and again found no consistent enhancement of LT tolerance attributable to freezing in either group. In agreement with our own and others’ anecdotal observations that some species can attain nearly maximal LT tolerance in the absence of freezing under field conditions, we conclude that freezing is neither required nor a major influence in LT acclimation, at least in well-studied boreal conifer species, while the effects of freezing on temperate conifers are not as well-documented. We conclude that freezing treatment of conifer seedlings to ensure sufficient hardiness for late planting seems to offer little practical advantage.     

羽衣甘蓝新品种冬春3、11号的选育

冬春3、11号羽衣甘蓝新品种植株板叶,株高13～15 cm,株幅25 cm×27cm,心叶幅16 cm×17 cm,外部叶片14～15片,颜色都为绿色,内部心叶21～24片,冬春3号心叶片颜色淡黄(白)色,中心叶片粉红色,冬春11号心叶片淡粉红色.生长排列紧密,包心,观赏性极优.是目前国内因地制宜育成的首批耐冻、晚抽苔的羽衣甘蓝杂优一代新品种,适合长江两岸及以北广大地区12月至3月填补室外盆花空白观赏.     

山西冬麦区小麦全蚀病发生规律及不同品种的耐病性鉴定

全蚀病在山西省冬麦区于小麦１～２分蘖期开始发病，灌浆期病势达到高峰，小麦一生均受到该病的胁迫。白穗出现时间的早晚与小麦千粒重和穗粒数之间呈高度正相关，相关系数分别为ｒ＝０．９９５９和ｒ＝０．８４５６，即白穗出现时间愈早，对二者的影响愈大。在小麦的适宜播种期内，随着播期的推迟，病害有明显减轻的趋势。通过模糊聚类分析，将供试品种分为４个类型，即耐病高产型、耐病中产型、感病中产型和感病低产型。