低温胁迫下转ICE1基因水稻养分变化的研究

采用盆栽试验,选用转ICE1基因水稻T_4-8株系和T_4-9株系及未转基因水稻（Oryza sativa L.）品种垦鉴稻10号为试验材料,研究苗期低温胁迫对转基因水稻氮、磷、钾养分吸收的影响。结果表明,低温胁迫期间,转基因水稻幼苗丙二醛含量维持在较低水平,SOD活性维持在较高水平;地上部分氮、磷、钾含量变化不大,一直维持在较高水平;地下部分氮、磷、钾含量呈缓慢下降趋势,但降幅比非转基因水稻小,在胁迫第10天,T_4-8株系和T_4-9株系氮含量均高出对照13.86%,磷含量分别高出42.31%和50.00%,钾含量均高出85.71%。说明在低温胁迫条件下,ICE1基因过量表达可以增强水稻的抗寒性,减轻低温对水稻的伤害,保持根系较强的吸收养分能力。     

水汽压差与钾素互作对高温下番茄营养吸收与光合特性的影响

空气水汽压差（VPD）是植物水分运输的主要驱动力,影响作物对营养的吸收。探究不同VPD与钾素对高温下作物营养元素的吸收与光合特性的影响对夏季番茄合理施肥与环境管理具有重要意义。试验以‘金棚14-6’番茄为试材,采用盆栽方式,设置2个VPD水平（高VPD、低VPD）与3个钾素水平 (2、4、8 mmol·L^-1)共6个处理,分析了VPD与钾素互作对高温下番茄幼苗氮磷钾吸收、气体交换参数、光合和CO₂响应等的影响。结果表明：与高VPD相比,降低VPD会对番茄植株各器官的氮、磷、钾含量产生稀释效应, 但随着钾素水平的提高,氮、磷、钾的积累量均会显著增加,各元素积累量分别增加了99.6%、98.1%和44.7%（氮）,57.4%、50.4%和51.6%（磷）,145.9%、71.5%和30.6%（钾）。在低VPD下,中钾水平更有利于干物质和氮、磷、钾元素的积累,其叶片的氮素积累量和叶片水势显著高于其他5个处理;且低VPD下的植株具有较大的光照、CO₂浓度适应区间和高光合及相关参数,包括光合速率P_n、气孔导度G_s、光饱和点LSP、表观量子效率AQY、暗呼吸速率R_d和初始羧化效率CE等,且均在中钾水平时取得最大值;同时蒸腾速率T_r、光补偿点LCP与光呼吸速率R_p等均显著降低。综上可知,高VPD下高钾水平和低VPD下中钾水平提高了番茄的光合性能、氮磷钾元素吸收量和干物质积累量,可作为夏季高温施肥与环境管理指标。     

轮作休耕模式对土壤细菌群落的影响

以黄土高原半干旱区9种轮作休耕模式土壤为研究对象,分别设残膜覆盖（T₂1）、伏天深耕（T₂2）、施牛羊粪（7 500 kg·hm^-2）+深翻耕（30 cm）+连续休耕3 a（T₂3）、施牛羊粪（7 500 kg·hm^-2）+深翻耕（30 cm）+连续种植豌豆3 a并在盛花期翻压还田（T₂4）、施牛羊粪（7 500 kg·hm^-2）+深翻耕（30 cm）+连续3 a种植豌豆（每kg豌豆种子拌根瘤菌粉8.5 g）并在盛花期翻压还田（T₂5）、玉米秸秆粉碎（还田量7 500 kg·hm^-2）+施牛羊粪（7 500 kg·hm^-2）+深翻耕（30 cm）+连续休耕3 a（T₂6）、玉米秸秆粉碎（还田量7 500 kg·hm^-2）+施牛羊粪（7 500 kg·hm^-2）+深翻耕（30 cm）+连续3 a种植毛苕子并在盛花期翻压还田（T₂7）、玉米秸秆粉碎（还田量7 500 kg·hm^-2）+施牛羊粪（7 500 kg·hm^-2）+深翻耕（30 cm）+连续3 a种植毛苕子并在盛花期翻压还田（T₂8）等8个处理,以连续休耕3 a为对照（CK）,采用16S rRNA扩增子测序技术对土壤细菌群落组成、丰度和多样性等特征进行研究,分析了土壤养分与细菌种群多样性的相关关系。结果表明,9种休耕轮作模式下,土壤细菌群落中相对丰度较高的前5位菌门依次为变形菌门（Proteobacteria）（26.33%～37.33%）、酸杆菌门（Acidobacteria）（17.93%～21.43%）、放线菌门（Actinobacteria）（12.42%～19.41%）、芽单胞菌门（Gemmatimonadetes）（6.98%～10.99%）和绿弯菌门（Chloroflexi）（6.48%～10.50%）。其中T₂1、T₂5处理显著升高了硝化螺旋菌门的相对丰度（分别为50.04%和42.44%）,T₂2处理显著提高了变形菌门和拟杆菌门的相对丰度（分别为31.51%和159.96%）,T₂6、T₂7处理显著增加了芽单胞菌门的相对丰度（分别为28.36%和28.33%）,T₂8处理显著增高了奇古菌门的相对丰度（519.79%）。不同轮作休耕模式的土壤全氮含量均高于CK。细菌群落丰富度指数除T₂7处理外,其余处理均高于CK。冗余分析和Monte Carlo置换检验结果显示,土壤全氮、全钾、速效氮含量对土壤细菌群落结构影响显著（P＜0.05）。     

外源5-ALA对干旱胁迫下玉米幼苗生长的缓解效应及抗氧化酶基因表达的影响

以抗旱玉米自交系郑58和干旱敏感自交系TS141为材料,研究了5-氨基乙酰丙酸（5-ALA）对15% PEG-6000模拟干旱胁迫下玉米幼苗生长的缓解效应及抗氧化酶基因表达的影响。结果表明：与对照相比,郑58及TS141在干旱胁迫下幼苗的苗长、鲜重、干重明显降低,郑58分别下降18.49%、29.06%和20.00%,TS141分别下降25.66%、23.97%和13.64%;叶片丙二醛（MDA）及过氧化氢（H₂O₂）含量明显增高,MDA含量分别提高了164.58%、263.53%,H₂O₂分别提高了134.95%、203.83%;超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化酶（APX）活性增加,郑58分别提高了65.61%、29.48%、68.49%、141.51%,TS141分别提高了63.01%、48.00%、85.68%、204.29%;叶绿素含量降低,分别降低33.46%、 42.26%;光合参数P_n、G_s、T_r下降,郑58的P_n、G_s、T_r分别下降48.78%、45.31%、52.39%,TS141的P_n、G_s、T_r分别下降57.66%、57.46%、65.14%;抗氧化酶基因SOD3、POD3、CAT1相对表达量提高,郑58分别提高54.58%、34.12%、69.70%,TS141分别提高54.95%、21.36%、59.34%。喷施25 mg·L^-1的5-ALA能明显缓解干旱胁迫对玉米幼苗造成的损伤,与PEG处理相比,玉米自交系郑58和 TS141的幼苗苗长、鲜重、干重明显增加,苗长分别增加了13.31%和11.21%,幼苗鲜重分别增加了22.29%和18.23%,幼苗干重分别增加了16.67%和10.53%;叶片中MDA含量分别降低了17.85%、25.39%,H₂O₂含量分别降低了23.26%、19.15%;SOD、POD、CAT和APX活性进一步增加,郑58分别增加16.49%、18.15%、36.98%和28.13%（P＜0.05）,TS141分别增加16.65%、16.54%、28.49%和26.76%（P＜0.05）;叶绿素含量和光合参数P_n、G_s、T_r增加,叶绿素含量分别增加18.29%、19.87%;光合参数P_n分别增加35.87%、42.12%,G_s分别增加36.63%、36.81%,T_r分别增加37.67%、67.88%;玉米幼苗叶片中抗氧化酶基因SOD3、POD3、CAT1相对表达量较干旱胁迫处理都有进一步提高,郑58分别提高20.99%、32.18%和23.51%,TS141分别提高25.97%、23.16%和40.94%。     

不同水肥配合对马铃薯产量的影响

通过马铃薯膜下滴灌水肥耦合盆栽试验,以补水时期（X₁）、补灌定额(X₂）、施氮量（X₃）、施磷量（X₄）、施钾量（X₅）为试验因素,采用5因素5水平（1/2实施）的二次旋转回归正交组合试验设计。研究了不同氮、磷、钾配施对马铃薯产量的影响,创建了马铃薯产量与补水时期、氮、磷、钾施用量和灌水量关系方程。结果表明：各因素的作用顺序为：X₅＞X₄＞X₃＞X₂＞X ₁,各因子的交互项对马铃薯产量的影响顺序为X₄X₅＞X₃X₅＞X₂X₄＞X₂X₅＞X₂X₃;在以产量为目标函数时,最高产量为33.785 t·hm^-2时,补水时期为苗期灌水总量为灌溉定额的25%、现蕾期灌水总量为灌溉定额25%、初花期灌水总量为灌溉定额的50%;水肥耦合关系为灌溉定额为822 m³·hm^-2,施氮量、施磷量、施钾量分别为73.5 kg·hm^-2、224.4 kg·hm^-2、223.8 kg·hm^-2。     

滴灌水钾一体化对猕猴桃光合特性的影响

为探明不同滴灌水钾一体化管理对猕猴桃光合特性的影响,以8 a生金艳猕猴桃为试材,设置对照处理CK（在果实膨大期即III期、果实成熟期即IV期灌水量分别为31.2、26.4 m³·667m^-2,施钾量分别为6.0、7.8 kg·667m^-2）,在III、IV期分别设置3个亏水水平（即轻度、中度、重度水分亏缺,记为LD、MD、SD,灌水量分别为CK的80%、60%、40%）和2个施钾水平（即低钾、高钾,记为LK、HK,施钾量分别为CK的60%和80%）。结果表明：果实膨大期、果实成熟期不同滴灌水钾一体化处理的光合指标日变化趋势相似;LD处理下叶片净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）、瞬时水分利用效率（WUEi）、羧化速率（CE）均随施钾量增加而增大,果实膨大期LDHK处理的Pn、CE较LDLK处理分别高15.71%、16.80%,果实成熟期LDHK处理的Pn、Gs较LDLK处理分别高6.07%、12.76%,差异达显著水平（P<0.05）;SD处理下,除胞间CO₂浓度（Ci）外各光合指标均较CK显著下降（P<0.05）;MD处理下,除Ci、WUEi外各光合指标均较CK显著下降（P<0.05）;施钾量一定时,除Ci、WUEi外各指标均随灌水量增加而显著增大（P<0.05）,增幅为11.42%~64.40%;与CK处理相比,果实膨大期LDHK处理Pn提高11.38%（P<0.05）,WUEi提高3.06%,CE提高10.83%;IV-LDHK处理Pn提高0.96%,WUEi提高2.00%。综合比较采用果实膨大期LDHK处理及果实成熟期LDHK处理,可在相应生育期节水节肥20%,日光合能力较强,是猕猴桃较适宜的滴灌水钾一体化管理模式。     

施用生物菌肥对桃园土壤养分及微生物功能多样性的影响

以不同施肥处理下的桃园土壤为试验材料,设置不同梯度的生物菌肥 T1（200 kg·667m^-2）、T2（300 kg·667m^-2）、T3（500 kg·667m^-2）及T4（1 000 kg·667m_-2）4个处理,以鸡粪为 CK（2 000 kg·667m^-2）,研究生物菌肥对桃园土壤养分及微生物功能多样性的影响。结果表明：随生物菌肥施用量的增加,桃园土壤pH值、有机质、铵态氮、速效钾、有效磷含量、微生物单孔颜色平均变化率(AWCD)、微生物多样性指数及微生物对六类碳源的利用强度先增加后降低,硝态氮含量下降。生物菌肥200 kg·667m^-2处理下,0~20 cm土层有效磷含量较CK提高53.98%（P＜0.05）,而与生物菌肥300 kg·667m^-2处理差异不显著。生物菌肥300 kg·667m^-2处理下,土壤微生物对羧酸类化合物利用强度最高,较CK提高22.67%(P＜0.05)。生物菌肥300 kg·667m^-2处理下20~40 cm土层的土壤有效磷、速效钾含量、微生物多样性指数（Simpson 优势度指数）及微生物对碳水化合物利用强度较CK分别提高33.49%、129.61%、0.22%和18.06%（P＜0.05）。冗余分析表明,土壤微生物对氨基酸化合物利用强度与有机质显著正相关,相关系数为0.68。主成分分析中,生物菌肥300 kg·667m^-2处理对土壤微生物多样性指数、碳源利用强度及土壤养分影响得分最高,分别为2.42和1.36。因此,生物菌肥能够提高土壤微生物活性、功能多样性、微生物对碳源的利用强度及养分含量,其中以生物菌肥300 kg·667m^-2处理效果最佳。     

马铃薯抗旱栽培土壤含水量及产量效益研究

于2014年在宣威市农业技术示范基地开展了玉米间作马铃薯集雨保墒抗旱栽培复合技术试验研究。试验处理包括：T₁：玉米+开沟覆膜‖马铃薯;T₂：玉米+打塘覆膜‖马铃薯;T₃：玉米+平作覆膜‖马铃薯;T₄：玉米平作覆膜单作;T₅：马铃薯单作。结果表明,T₁和T₂处理玉米土壤含水量均高于其它处理,T₁、T₂处理0～7.6 cm土层玉米平均土壤含水量比T₄处理最多增加28.32%,0～20 cm土层最多增加28.12%;间作处理马铃薯的土壤含水量均高于马铃薯单作,T₁、T₂处理马铃薯平均土壤含水量在0～7.6 cm和0～20 cm两个土层分别比T₅处理最多增加23.52%和12.78%;T₁、T₂处理玉米产量、复合产量和土地当量比（LER）均高于T₃处理,其中,T₂处理的土地当量比最大（LER=1.20）,比T₃处理增加10.52%,产量效益明显。     

施氮对关中地区冬小麦农田土壤呼吸的影响及基于植被指数的估算模型

为探寻不同施氮量对农田土壤呼吸（R_S）的影响并快速准确估算R_S,以关中地区冬小麦为研究对象,观测了5种施氮量下冬小麦农田R_S的变化,研究了环境因子（土壤温度、土壤湿度）及作物因素（叶面积指数、地上部生物量、SPAD值）对于R_S的影响,建立了适用于关中地区土壤温度与植被指数下的农田土壤呼吸估算模型。设置秸秆还田下的5种施氮量处理,分别为传统施氮量SN200（200 kg·hm^-2）、优化施氮量SN150（150 kg·hm^-2）、60%优化施氮量SN120（120 kg·hm^-2）、50%优化施氮量SN100（100 kg·hm^-2）以及不施氮肥SN0（0 kg·hm^-2）。结果表明：不同施氮量下R_S随生育期推进均表现为先升高再降低的趋势,同时添加氮肥促进了R_S排放。各处理观测期内R_S的均值为：SN200（3.68 μmol·m^-2·s^-1）>SN150（3.40 μmol·m^-2·s^-1）>SN120（3.06 μmol·m^-2·s^-1）>SN100（2.70 μmol·m^-2·s^-1）>SN0（2.21 μmol·m^-2·s^-1）。不同施氮量下冬小麦冠层近红外波段反射率在拔节期和抽穗期差异明显,反射率从高到低依次为SN200>SN150>SN120>SN100>SN0,而在灌浆期和成熟期差异不大。土壤温度显著影响了R_S（P<0.01）,土壤湿度与R_S没有显著相关关系（P0.05）。叶面积指数、地上部生物量、SPAD值和植被指数均与R_S呈显著相关关系（P<0.05）。通过多种模型评估,建立基于植被指数和土壤温度的最佳农田土壤呼吸估算模型,显著高于基于土壤温度的单因子模型,模型精度可达到0.6以上（n=120）。     

水肥供应对马铃薯根层养分及产量的影响

以陕北地区普遍种植的马铃薯品种荷兰15号为供试材料,设置灌水水平和施肥量两因素,研究水肥供应对马铃薯根层养分及产量的影响。以100%ET₀（W1）和当地推荐施肥量（F1,N-P₂O₅-K₂O为240-120-300 kg·hm^-2）为基础,3个灌水量处理分别为W1,W2（80%ET₀）和W3（60%ET₀）,3个施肥水平分别为F1,F2（75%F1）和F3（50%F1）,以60%ET₀灌水水平和不施肥处理为对照组（CK）,共10个处理。结果表明：不同水肥供应对马铃薯各生长阶段耗水量及水分利用效率有显著的影响,随着灌水量增加,土壤水分逐渐向下层迁移;在马铃薯整个生育期,W3F2处理水分利用效率最高,为44.69 kg·hm^-2·mm^-1,其次为W2F2(44.41 kg·hm^-2·mm^-1),比CK分别高39.64%和38.75%;W3F1处理在10~60 cm土层硝态氮含量平均值最高,比CK高166.1%,W2F2在10~60 cm土层铵态氮含量平均值最高,比CK高61%,W3F3在10~60 cm土层电导率平均值最高,比CK增高48.44%。W2F2处理的土壤养分含量较高,主要集中在10~30 cm土层;W2F2处理的产量最高,为12 539.33 kg·hm^-2,比CK处理的产量高55.65%,且变异系数小。因此,该地区推荐的灌水量为80%ET₀,施肥量N-P₂O₅-K₂O为180-90-225 kg·hm^-2。     

The involvement of ethylene and calcium in gray mold of pelargonium,ruscus, and rose plants

Leaves ofPelargonium domesticum andRuscus hypoglossum infected byBotrytis cinerea Pers., produced 12 and 1.5 nl ethylene/h/g, respectively, 34 days after inoculation; wounded or healthy leaves and phyloclades of them produced much lower amounts. When the fungus was grown on dead leaves it produced negligible amounts of the gas even when supplemented with methionine. Exogenous ethylene enhanced gray mold development in both hosts. Silver thiosulfate, aminooxyacetic acid (AOA) and aminoethoxyvinylglycine significantly inhibited disease development in pelargonium, and the latter two compounds inhibited ethylene production. AOA inhibited disease development and ethylene production in cut rose flowers; calcium ions inhibited disease development whereas the chelator EGTA [ethylene glycol bis-(β-aminoethyl ether)N,N,N′,N′-tetraacetic acid] enhanced it. Disease suppression by an excess of Ca²⁺ was correlated with repression of ethylene production by the flowers, whereas deficiency in Ca²⁺ increased disease severity. Publication of the Agricultural Research Organization. No. 2413-E, 1988 series.     

Powdered neem seed and cake for management of the banana weevil,cosmopolites sordidus, and parasitic nematodes

Field trials were conducted in Kenya with ‘Nakyetengu’, an East African highland banana cultivar (AAA-EA), highly susceptible to banana pests. Regardless of soil fertility levels, incorporation around the plant base of powdered neem(Azadirachta indica A. Juss.) seed or cake at 60-100 g/mat at 4-month intervals, gave better control of the banana weevil,Cosmopolites sordidus (Germar), and of parasitic nematodes, than that achieved with soil application of Furadan 5G (carbofuran) at 60 g/mat at 6-month intervals. Compared with untreated control, fruit yield in most of the neem treatments was significantly higher, particularly during the second cycle of crop production. Neem application conferred a net economic gain, whereas Furadan application proved uneconomical. Application of powdered neem seed or cake at higher rates (200–400 g/mat) at 6-month intervals caused phytotoxicity, resulting in drying up of banana plants before fruiting, or in ‘chokethroat’,i.e., inflorescence emergence failure.     

Effects of inoculum density, leaf age, moisture, temperature, and wetness duration on black streak of edible burdock

Inoculum density, temperature, leaf age, and wetness duration were evaluated for their effects on the development of black streak (Itersonilia perplexans) on edible burdock (Arctium lappa L.) in a controlled environment. The effect of relative humidity (RH) on ballistospores production by I. perplexans was also evaluated. Symptoms of black streak on leaves increased in a linear fashion as the inoculum density of I. perplexans increased from 10² to 10⁶ ballistospores/ml. Rugose symptoms on young leaves were observed at densities of ≥10⁴ ballistospores/ml. Disease severity of I. perplexans in relation to leaf age followed a degradation curve when the leaves were inoculated with ballistospores. Disease severity was high in newly emerged leaves up to 5 days old, declined as leaf age increased to 29 days, and was zero when leaf age increased from 30 to 33 days. Disease development of edible burdock plants exposed to ballistospores of I. perplexans was evaluated at various combinations of temperature (10°, 15°, 20°, 25°C) and duration of leaf wetness (12, 24, 36, 48, and 72 h). Disease was most severe when plants were in contact with the ballistospore sources at 15° or 20°C. The least amount of disease occurred at 25°C regardless of wetness duration. Ballistospores required 24–36 h of continuous leaf wetness to cause visible symptoms by infection on edible burdock. Ballistospores production in infected lesions required at least 95.5% RH.     

Tumours of Begonia and some other ornamentals,induced by Corynebacterium fascians

In 1975 many tumours were observed in plants ofBegonia Schwabenland grown in Aalsmeer. Submersion of the roots ofNicotiana megalosiphon seedlings in a homogenate of tumorous tissue, induced tumours after two weeks. Short periods of submergence yielded results similar to those obtained after longer periods. Tumour homogenates lost their infectivity after ten min at 50°C. Aphids transmitted the infectious agent.Treatment with propylene oxide did not inhibit infectivity completely. Filtration through a 450 nm filter removed the infectious agent.Tobacco tumor virus or a viroid could not be isolated. Cultures ofCorynebacterium fascians, isolated from tumours ofN. megalosiphon were highly infectious and induced tumours in healthyN. megalosiphon andBegonia. Tumorous tissue homogenates ofPelargonium zonale, Dahlia sp.,Gladiolus sp., andLilium sp. also caused tumours inN. megalosiphon, from whichC. fascians was isolated. It was not possible to produce tumours inN. megalosiphon with homogenates from roses with symptoms of bud proliferation.Samenvatting In 1975 werden vele tumoren waargenomen inBegonia Schwabenland op Aalsmeerse bedrijven (Fig. 1). De infectiositeit van tumorweefsel kon goed en snel worden vastgesteld door de wortels van zaailingen vanNicotiana megalosiphon in een homogenaat van tumorweefsel te dompelen. Tumoren ontstonden na twee weken, de eindbeoordeling geschiedde na een maand (Fig. 2). Ook verschillende andereNicotiana spp.,Melilotus officinalis (Fig. 3) enPisum odoratum (Fig. 4) werden aangetast.Bij de infectiositeitstoets gaven zeer korte dompeltijden even goede resultaten als langere (Tabel 1). Infectieus sap verloor zijn infectievermogen na 10 min verhitting bij 50°C. Bladluizen brachten de smetstof over. Propyleenoxide verminderde de infectiositeit wel, doch onderdrukte deze niet totaal. Bij filtratie door een 450 nm filter bleef het infectieuse agens op het filter achter. Het tumor-inducerende agens was ook aanwezig in die delen van planten met tumoren welke gezond leken en het ging voor een gering deel over met zaad (Tabel 2).Uit tumoren konden wij geen tabakstumorvirus of een viroïde isoleren. Culturen vanCorynebacterium fascians, geïsoleerd uit tumoren vanN. megalosiphon bleken zeer infectieus en veroorzaakten tumoren inN. megalosiphon enBegonia. Homogenaten van tumorweefsel vanPelargonium zonale, dahlia (Fig. 5), gladiool (Fig. 6) enLilium Mid Century Hybrid Enchantment (Fig. 7) veroorzaakten ook tumoren opN. megalosiphon, waaruitC. fascians werd geïsoleerd. Met sap van kroeskopzieke rozen konden wijN. megalosiphon niet besmetten.     

Fusarium Redolens f.sp asparagi, Causal Agent of Asparagus Root Rot, Crown Rot and Spear Rot

Two Fusarium species, F. oxysporum f.sp. asparagi and F. proliferatum, are known to be involved in the root and crown rot complex of asparagus. We have investigated reports on the involvement of F. redolens, a third species, which until recently was considered conspecific with F. oxysporum because of morphological similarities. RFLP analysis of the rDNA internal transcribed spacer region and AFLP fingerprinting identified eight strains from asparagus unambiguously as F. redolens. Four of these were tested and found to be pathogenic to asparagus either in this study (two strains) or in a previous one in which they were classified as F. oxysporum (three strains). Disease symptoms and disease development were the same as with F. oxysporum f.sp. asparagi and F. proliferatum. Present data and literature reports identify F. redolens as a host-specific pathogen involved in root, crown and spear rot of asparagus. The pathogen is formally classified as F. redolens Wollenw. f.sp. asparagi Baayen.     

Phylogenetic analyses of plant-growth-promoting rhizobacteria isolated from tomato,lettuce, and Japanese pepper plants in Hyogo Prefecture,Japan

Approximately 30,000 fluorescent bacterial strains isolated from tomato, lettuce, eggplant, Chinese cabbage, and Japanese pepper plants at seven different locations in Hyogo Prefecture, were screened for plant-growth-promoting (PGP) activity to induce disease resistance against bacterial wilt in tomato. The 37 strains that had higher PGP activity were subjected to molecular phylogenetic analyses using the sequences of the 16S rRNA, gyrB and rpoD genes. Most of the strains were identified as Pseudomonas fluorescens or its close relative, P. putida, while a few strains were grouped with more distantly related bacterial species such as Enterobacter and Stenotrophomonas. The phylogenetic relationships among tomato and lettuce isolates mostly coincided with the source locality and host plants, with a few exceptions. In contrast, isolates from Japanese pepper plants did not form their own cluster but represented several different bacterial species.     

Bacterial induction of the accumulation of phaseollin,pisatin and rishitin and their antibacterial activity

Bean hypocotyls, pea pods and tomato fruits were tested for phaseollin, pisatin and rishitin production when challenged with the phytopathogenic bacteriaErwinia carotovora, Pseudomonas phaseolicola, P. pisi andP. solanacearum, and their isolated extracellular polysaccharides. All bacteria induced phytoalexin accumulation, whereas only phaseollin and pisatin, but not rishitin, were elicited by EPS. The inhibitory effect of these three phytoalexins on bacterial growth was studied in liquid medium; whereas phaseollin and pisatin strongly inhibited growth, only a slight inhibitory effect resulted from the presence of rishitin in the medium.Samenvatting Bonehypocotylen, erwtepeulen en tomatevruchten werden onderzocht op hun vermogen tot vorming van respectievelijk faseolline, pisatine en rishitine, na inoculatie met de fytopathogene bacteriënErwinia carotovora, Pseudomonas phaseolicola, P. pisi enP. solanacearum en na behandeling met oplossingen van hun extracellulaire polysacchariden (EPS). Alle bacteriesoorten induceerden fytoalexinevorming, terwijl hun EPS wel faseolline- en pisatine-, maar geen rishitinevorming induceerden. Faseolline en pisatine remden de groei van de bacteriën in vloeibaar medium sterk; rishitine daarentegen had slechts een geringe groeiremming tengevolge.     

食物对兹沃尔新小绥螨生长发育和繁殖的影响

为探究不同食物对兹沃尔新小绥螨Neoseiulus zwoelferi种群生长、发育和繁殖的影响,采用年龄-龄期两性生命表分析测定兹沃尔新小绥螨取食卢氏叶螨Tetranychus ludeni、甜果螨Carpoglyphus lactis和香蒲Typha orientalis花粉后的存活率、发育历期、寿命及繁殖情况。结果显示,3种食物均能满足兹沃尔新小绥螨生长发育和繁殖的需求。卢氏叶螨处理组的净增殖率和总繁殖率分别是28.99和36.99,均显著高于其他2个处理组;以甜果螨、卢氏叶螨和香蒲花粉为食的兹沃尔新小绥螨从卵发育至成螨所需时间分别为5.28、7.34和6.87 d,种群倍增时间分别3.35、4.22和11.77 d,前者显著短于其他2个处理;甜果螨处理组和卢氏叶螨处理组的雌成螨平均寿命分别比香蒲花粉处理组长2.75 d和4.92 d,但两者之间无显著差异;卢氏叶螨处理组雌成螨产卵天数最长,为17.84 d,产卵前期时间最短,为2.75 d,产卵量最大,为38.15粒/雌;香蒲花粉处理组雌成螨产卵天数最短,仅1.82 d,产卵前期时间最长,为5.89 d,产卵量最少,为3.36粒/雌。甜果螨处理组的内禀增长率、周限增长率分别为0.21 d-1和1.23 d-1,均显著高于其他处理组,但平均世代周期为14.65 d,显著低于其他处理组。表明3种食物均可使兹沃尔新小绥螨完成整个世代,其中甜果螨是室内饲养兹沃尔新小绥螨的最佳食物,香蒲花粉可以作为短期饲养的食物。     

Diagnostics,genetic diversity and pathogenic variation of ascochyta blight of cool season food and feed legumes

Molecular diagnostic techniques have been developed to differentiate the Ascochyta pathogens that infect cool season food and feed legumes, as well as to improve the sensitivity of detecting latent infection in plant tissues. A seed sampling technique was developed to detect a 1% level of infection by Ascochyta rabiei in commercial chickpea seed. The Ascochyta pathogens were shown to be genetically diverse in countries where the pathogen and host have coexisted for a long time. However, where the pathogen was recently introduced, such as A. rabiei to Australia, the level of diversity remained relatively low, even as the pathogen spread to all chickpea-growing areas. Pathogenic variability of A. rabiei and Ascochyta pinodes pathogens in chickpea and field pea respectively, appears to be quantitative, where measures of disease severity were based on aggressiveness (quantitative level of infection) rather than on true qualitative virulence. In contrast, qualitative differences in pathogenicity in lentil and faba bean genotypes indicated the existence of pathotypes of Ascochyta lentis and Ascochyta fabae. Therefore, reports of pathotype discrimination based on quantitative differences in pathogenicity in a set of specific genotypes is questionable for several of the ascochyta-legume pathosystems such as A. rabiei and A. pinodes. This is not surprising since host resistance to these pathogens has been reported to be mainly quantitative, making it difficult for the pathogen to overcome specific resistance genes and form pathotypes. For robust pathogenicity assessment, there needs to be consistency in selection of differential host genotypes, screening conditions and disease evaluation techniques for each of the Ascochyta sp. in legume-growing countries throughout the world. Nevertheless, knowledge of pathotype diversity and aggressiveness within populations is important in the selection of resistant genotypes.