影响芒果炭疽病病斑扩展的因素

采用离体叶片接种法,研究分生孢子浓度、芒果抗病性、温度、相对湿度、光照条件等因素对芒果炭疽病病斑扩展的影响.结果表明:分生孢子悬浮液浓度对病斑扩展有显著影响,接种4个分生孢子就能引起侵染;不同的芒果品种抗性级别和病斑大小之间显著相关;适合病斑扩展的温度是24～33℃,最适宜温度28℃;高湿和全黑暗条件有利于病斑的扩展.     

水稻胡麻斑类似病危害转Bt稻“克螟稻”初报

 于田间转Bt稻“克螟稻”稻叶上观测到一种病斑，病斑中心和周围均呈褐色，长椭圆形与稻胡麻斑病类似，平板上分离到的病原菌菌丝呈灰褐色，菌丝有多个隔膜，分生孢子梗成丛，但在PDA培养基上，产生的分生孢子特征与稻胡麻斑病不吻合。从为害级别和严重度上分析克螟稻对胡麻斑类似病的感病程度远远超过其亲本秀水11。克螟稻叶片间发病速率增长迅速，而秀水11叶片间发病速率增长缓慢。     

玉米灰斑病及抗性研究

玉米灰斑病由尾孢菌引起。尾孢菌在玉米叶粉碳酸钙琼脂培养基上能够产生分生孢子。采用注射法可以进行人工接种,空气湿度大、温度适宜条件下利于病害发生。参考玉米大、小斑病国家调查标准,提出9级标准记载植株灰斑病发病级别。研究表明,以推广种植抗病品种为主,辅助以栽培管理的综合防治措施是防治玉米灰斑病的有效途径。目前,在我国主要玉米种质中,仅有PB类群种质表现为抗灰斑病,四平头、旅大红骨、PA等类群种质多表现为感病。随着玉米灰斑病危害加重,应加强玉米灰斑病抗性基因发掘、种质改良和创新研究。     

野生大豆田间感染大豆灰斑病简报

大豆灰斑病(Cercospora Sojina Hara)又称蛙眼病,1915年首先在日本报道,现已遍布美国、巴西、中国、日本等主要大豆产区。我国黑龙江、吉林、辽宁、河北、山东、安徽、江苏、福建、四川、广西等地均有此病为害。病原真菌属半知菌类,为害大豆子叶、叶片、茎、荚及籽粒,叶片上病斑灰褐色、园形、周围有狭窄的暗褐色边缘     

大豆感染灰斑病菌后过氧化物酶活性的变化

本研究通过分析不同抗性的大豆品种接种灰斑病菌1-10号生理小种后，叶片中过氧化物酶（POD）活性变化的规律，探讨了过氧化物酶在大豆抗灰斑病中的作用。研究结果表明，大豆抗感品种接种灰斑病菌后，叶片中过氧化物酶活性比对照植株叶片中过氧化物酶活性均有所增高，并且抗感品种接种后叶片中过氧化物酶活性变化的幅度因生理小种的不同而不同，可见，大豆感染灰斑病菌后叶片中过氧化物酶活性的变化是大豆一种普遍性的抗病反应，而且抗感品种之间过氧化物酶活性变化差异并没有明显的规律性。因此，不宜作为一种生化指标来鉴定大豆品种对灰斑病的抗性。     

大豆叶片结构与灰斑病抗性的研究 Ⅰ．大豆叶片气孔密度、茸毛密度与灰斑病抗性的关系

采用火棉胶法和水合氯醛法研究了大豆叶片气孔密度、茸毛密度与灰斑病抗性的关系。试验结果表明，抗病品种和感病品种叶片正面和背面的茸毛密度并没有什么差异；但抗病品种叶片正面及叶片背面的气孔密度明显少于感病品种，这是抗病品种抵抗菌丝侵入的第一结构屏障。     

翠贝防治人参斑病试验报告

翠贝50％干悬浮剂具有保护、治疗和根治的仿生杀菌剂,在防治人参斑病属首次应用。试验证明翠贝3000倍液防治人参斑病效果最佳,且对病害具有治疗作用,对发病的人参叶片控制效果极佳,防效达83．3％,是值得推广应用的一种新型农药。     

大豆灰斑病抗感标准划分的研究

大豆灰斑病抗感鉴定标准的确立一直是抗病育种及抗病机理研究中的关键问题，也是一个难点。本文以大豆杂交组合的后代为材料，从各组合F2植株的病情分布、F3株系的抗感分离以及植株抗重复再侵染能力的角度，对大豆抗灰斑病的抗感鉴定标准进行研究。提出：在用混合菌种对大豆材料进行田间接种的条件下，大豆灰斑病的抗感鉴定标准应定在病斑型级数为B2处，即植株叶片的病斑数量不能超过5-8个。     

灰斑病所致大豆品质与产量损失的研究

采用不同病叶、病粒,对大豆灰斑病所致大豆品质和产量的影响进行了研究,结果发现:灰斑病直接影响大豆叶片全N含量及籽粒氨基酸与蛋白质含量.叶片中的全N含量随病情加重而减少,病粒中17种氨基酸总量、蛋白质和脂肪含量与病叶一样也随病情加重而递减.灰斑病引致的大豆产量损失与病粒率和籽粒病指相关密切,与病粒率的相关系数为0.9723,与籽粒病指的相关系数为0.9763.根据相关系数建立两个方程,用(Y)=-0.1890 1.4063X10.7993(X1病粒率)和(Y)=2.6034 1.338X2(X2病指)可预测大豆由灰斑病病粒引致的减产量,用n'=Int[(YBL×100-8)]/(5 1)可预测当年大豆的等级,并以EL=YM×(1-YLL)×PWn'预测经济损失.     

不同抗性大豆品系感染灰斑病后脂质过氧化作用的变化

以三个抗灰斑病和三个感病品系为试材，分析了不同抗性大豆品系感染灰斑病后叶片中过氧化作用的变化。结果表明：１．大豆感染灰斑病后超氧物歧化酶活性均有所增加，且有感病品系超氧物歧化酶活性高于抗病品系的趋势；２．大豆感染灰斑病后过氧化物酶活性也有所增加，感病后感病品系的过氧化物酶活性明显高于抗病品系的；３．大豆感染灰斑病后所有品系的抗坏血酸含量均降低，感病后感病品系的抗血酸含量高于抗病品系的；４．大豆感染     

Effects of beet yellows virus and beet mild yellowing virus on leaf area dynamics of sugar beet (Beta vulgaris L.)

Field experiments were conducted over three years to investigate the effects of beet yellows virus (BYV) and beet mild yellowing virus (BMYV) on leaf area dynamics in sugar beet (Beta vulgaris L.). Plants infected with BMYV showed normal leaf area growth and the leaf area index (LAI) was not significantly affected by virus infection. Up to 1.4 m² (leaf) m⁻² (soil) of leaf area was yellow, resulting in a maximum proportion of yellow leaf area of ca. 35%. Yellowing symptoms were only found on mature leaves. Plants infected with BYV showed a reduced formation of leaf area compared to healthy or BMYV-infected plants; leaves appearing after infection remained smaller than in healthy or BMYV-infected plots. As for BMYV, only mature leaves developed yellowing symptoms. The total amount of yellow leaf area on BYV-infected plants was similar to that induced by BMYV, but due to the smaller total leaf area index, the proportion of yellow leaf area was greater, up to ca. 50%. Infection with BYV substantially reduced the life span of infected leaves. Both viruses caused a ±20% decrease of specific leaf area in mature yellow leaves, compared to healthy leaves. As a result of a lower LAI and a greater proportion of yellow leaf area, BYV causes a greater reduction of crop light interception on green leaves than BMYV. In BMYV-infected plots, proportion of soil cover by yellow leaves was generally similar to the proportion of yellow leaf area, but significant differences from this pattern were observed for BYV.     

大豆叶片生理生化性状与多聚不饱和脂肪酸形成关系的研究

利用我国东北高油大豆品种(系)和国外低亚麻酸突变体及其同位基因系,对始花五周后的最大叶片的叶质重、叶绿素和种子的脂肪、脂肪酸、脂肪酶、亚油酸氧化还原酶进行分析结果表明:大豆亚油酸含量与叶绿素b、亚油酸氧化还原酶活性、结荚至成熟期的日照时数呈相关。而亚麻酸含量则与叶质重、结荚至成熟期间的累积温度呈正相关。大豆脂肪含量与叶质重呈显著负相关,而与脂肪酶活性呈正相关。提高大豆种子多聚不饱和脂肪酸R=(18:1)/(18:2+18:3)值是改善油质和提高其含油量的一个较好的选择途径。     

减氮对豫北限水灌溉冬小麦冠层结构和光合特性的影响

为了解节水栽培条件下冬小麦光合对减氮的反应,以豫北地区冬小麦为研究对象,在限水灌溉(春浇一水)条件下,以当地冬小麦生产中常规施氮量(底施氮量+追施氮量:120+210 kg·hm~(-2))为对照,设置不同减氮处理(底施氮量+追施氮量分别为120+150、120+90、120+0、0+0 kg·hm~(-2)),研究减氮对冬小麦冠层叶片和非叶器官形态特征、冠层光分布和光合速率的影响。结果表明,随施氮量的减少,小麦开花期单茎叶面积、上三叶面积及旗叶节以上非叶绿色器官面积均呈下降趋势,降幅分别为9.7%～28.0%、10.6%～30.3%和5.2%～16.8%,叶器官面积和上三叶面积下降幅度均高于旗叶节以上非叶绿色器官面积的下降幅度。减氮处理下,开花期上三叶长和宽分别减少4.4%～8.8%和11.8%～15.6%,叶片变窄变短,而倒四叶叶型无明显变化。另外,上三叶平均比叶重随氮肥减少总体呈增加趋势,表明适量减氮有助于改善上三叶叶片质量。随施氮量的减少,花后各叶层透光率呈增加趋势,其中灌浆中前期(开花至花后20 d)减氮处理的倒四叶层、倒三叶层、倒二叶层和旗叶层透光率分别比对照高39.0%、38.0%、23.8%和9.4%。随施氮量的减少,花后上三叶光合速率总体均呈先略升后降的趋势,其中旗叶和倒二叶光合速率在花后均以120+210 kg·hm~(-2)、120+150 kg·hm~(-2)和120+90 kg·hm~(-2)处理较高,且处理间差异较小,而倒三叶光合速率在开花至花后18 d均以120+150 kg·hm~(-2)和120+90 kg·hm~(-2)处理较高,分别比对照高38.7%和24.7%。这说明,减氮减少了冬小麦单茎叶面积,增加了非叶器官面积占单茎总光合面积的比例,且上三叶叶片变小,叶片质量提高,增加了花后冠层下部叶片受光比率,改善了冠层下部叶片的受光状况,有利于提高冠层下部叶片的光合速率。     

NP配比对专用高蛋白大豆产量和品质的调节效应

采用田间试验研究了不同NP配比对南农88-31大豆产量和品质的调节效应.结果表明,最有利于南农88-31大豆籽粒产量和蛋白质产量提高的NP配比是N150kg/hm2与P2O575kg/hm2;NP配比可以调节大豆叶面积和干物质积累,但这种调节效应主要归功于氮肥的作用,随施N量增加,大豆叶面积和干物质积累增加;NP配比对大豆籽粒蛋白质含量的调节效应不明显.     

The effect of cutting on the proportions of perennial ryegrass and white clover in mixtures

In two experiments with ryegrass/white clover mixtures, the proportion of clover was measured before and after cuts which removed 8-75% of above-ground biomass. Cutting was found to reduce the proportion of clover leaf area in the crop in both experiments, sometimes by as much as two-thirds, and the proportion of clover dry weight, by up to half, in one of them. That is, the harvested material contained a greater proportion of clover than did the sward before the cut. This disproportionate removal of clover was due to clover having a greater proportion of its leaf near the top of the canopy than grass. It showed that preferential removal of clover occurs as a result of the purely passive selection by a mower, not only as a result of grazing by animals which may be capable of active as well as passive selection.
Despite the disadvantage to clover of losing more of its leaf area than grass, and in some cases more of its dry weight also, when the mixture was cut, the clover content of the sward did not decrease during the growing season as a whole. This was because, where no nitrogen fertilizer was applied, clover had a greater relative growth rate (RGR) than its companion grass during the growth periods between cuts and this increased its percentage of the mixture. Even where nitrogen was applied, clover equalled the RGR of grass and maintained its proportion of the crop, except in one instance.     

移栽期及抗寒剂对烤烟生长发育及产量的影响

为有效规避烤烟生产中前期低温胁迫、后期高温逼熟的不利气候条件,在大田条件下,开展了不同移栽期及抗寒剂使用对烤烟生长发育和产量及其构成的影响。结果表明,提前5d膜下移栽,烟株叶片数较多,叶面积适中;提前10 d膜下移栽,烟株叶片数略少,但叶面积最大;单独使用抗寒剂会出现叶片细长现象,而配合提前膜下移栽,更有利于烤烟上中等烟比例和产量的提高。     

大豆群体结构的研究

对大豆群体冠层上部实施不同比例的剪叶、去荚处理和运用二元多项式模型作了大豆群体“源、库”及产量的生长分析。结果表明:大豆群体的叶面积指数控制在5.1左右为最适宜。创造合适的群体“源、库”比,协调光合性能诸因素,是获取高产的关键。通过调整冠层叶面积的分布,提高群体中、下部的光强,可以达到提高产量的效果。文中还讨论了利用“源、库”理论来探索最适叶面积指数和群体结构的问题。     

Characterization for industrial purposes of the fibre anatomy of perennial ryegrass and tall fescue stem and leaf at three stages in the primary growth

Characterization of grass fibre is important in assessing its potential for industrial fibre applications. Stem and leaf sections were sampled from triplicate field plots of two grass species, perennial ryegrass (PRG) and tall fescue at three dates (monthly from 12 May) in the primary growth, and were used to (a) isolate individual fibre cells and (b) prepare transverse sections. Microscopy and image analysis software were used to determine the length and width of individual fibre cells and the proportion of lignified fibre in stem and leaf transverse sections. The length and width of individual fibre cells were greater (P < 0·001) in stem than in leaf sections, while individual fibre cell length was greater (P < 0·01) for tall fescue than PRG. Harvest date and grass species had little effect (P > 0·05) on the proportion of lignified fibre in the transverse‐sectional area. However, there was a greater (P < 0·001) proportion of lignified fibre in the transverse‐sectional area of grass stems than leaves, with tall fescue having a greater (P < 0·05) stem and leaf transverse‐sectional area and area of lignified fibre in transverse section than PRG. Tall fescue harvested at a later stage of growth, with higher proportions of stem than leaf tissue, may be more suitable for industrial fibre applications.     

SOME COMPARISONS OF INCLINED POINT QUADRAT AND AIRFLOW PLANIMETER METHODS FOR MEASURING LEAF-AREA INDEX OF GRASS SWARDS

The leaf-area indices (LAI) of simulated swards of three populations of Festuca arundinacea Schreb. were estimated by use of an inclined point quadrat and an air-flow planimeter.
Both for comparisons of leaf areas before defoliation, and for comparisons of leaf areas removed by defoliation, very highly significant relationships were found between estimates by the two methods. In five out of six cases the airflow-planimeter estimates of leaf area became greater than those from the inclined point quadrat as sward leaf area increased.
It is suggested that the major factor responsible for departure from complete agreement between the methods is a difference in leaf areas actually measured by the two methods; in addition, there was some indication of operator error with the inclined point quadrat. The results indicated that these factors were not greatly influenced by leaf canopy arrangement.     

THE INFLUENCE OF SEASONAL CHANGES IN LIGHT ENERGY ON LEAF AND TILLER DEVELOPMENT IN RYEGRASS, TIMOTHY AND MEADOW FESCUE

The importance of leaf area as a determinant of yield in herbage crops is now widely realized. Selection for a rapid increase in leaf area might therefore be a useful approach to the problem of breeding for yield.
The present paper describes the seasonal changes in two important components of leaf area, rate of leaf and tiller production, in contrasting varieties of ryegrass, timothy and meadow fescue. The regular seasonal variation in these components in the glasshouse is shown to be determined primarily by available light energy, the species and varieties differing in their response to changes in light energy. The possibilities of selection for these components of leaf area are discussed, but it is pointed out that individual leaf size must also be considered.