钙对弱光亚适温下黄瓜光合作用的影响

【目的】探讨钙对弱光亚适温下黄瓜光合功能的影响机理,为寻找缓解弱光亚适温逆境障碍的有效措施提供理论依据。【方法】10mmol·L-1CaCl2溶液喷撒黄瓜幼苗,清水处理作对照,连喷5d后利用光照培养箱模拟弱光亚适温条件对黄瓜幼苗进行处理。【结果】弱光亚适温胁迫使黄瓜幼苗的光合诱导时间延长,光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)、羧化效率(CE)、表观量子效率(AQY)、实际光化学效率(φPSⅡ)、光化学猝灭(qP)及电子传递速率(ETR)等降低,非光化学猝灭(NPQ)升高。胁迫前用10mmol·L-1CaCl2预处理,黄瓜幼苗的光合诱导时间缩短,Pn、Gs、Ci、CE、AQY、qP、ETR等都有不同程度的提高,NPQ有所降低。【结论】弱光亚适温下气孔与非气孔限制因素同时存在,气孔导度下降和碳同化降低都是引起黄瓜光合速率降低的重要原因。Ca2+对减轻弱光亚适温对黄瓜幼苗光合作用的影响发挥积极作用。     

山黧豆根腐病病原菌亚洲镰孢菌的分离鉴定

为了明确山黧豆（Lathyrus sativus）根腐病病原菌的分类地位,本研究于2018年8月在四川省南充市采集山黧豆根腐病病样,经组织分离法进行分离纯化,采用形态学和翻译延伸因子（Translation elongation factor 1-agene,EF-1α）基因序列分析相结合的方法对致病菌进行鉴定。结果表明：从采集的山黧豆根腐病病样上共分离获得39株分离物,其中3株分离物Shan-27,Shan-28和Shan-29对山黧豆具有强致病性,分离频率为7.69%;这3株致病菌在形态学上均接近于禾谷镰孢菌复合种（Fusarium graminearum species complex）,而对其翻译延伸因子（EF-1α）序列分析发现,其均与亚洲镰孢菌聚在同一分支上,同源性达99%以上。因此,根据菌株形态学特征和EF-1α基因序列分析结果,将引致山黧豆根腐病的病原菌确定为亚洲镰孢菌（Fusarium asiaticum）。     

施用氨基酸肥料对连作条件下黄瓜的生物效应及土壤生物性状的影响

为探讨施用氨基酸肥料对连作条件下黄瓜生长及土壤微生物的影响,本研究采用盆栽试验的方法对黄瓜（Cucumis sativus）的生物学效应及土壤微生物群落结构进行测定和分析.结果显示：施用氨基酸肥料（AAF）使黄瓜生物学性状得到显著改善,黄瓜的叶绿素增加、叶面积增大、光合作用增强,干重提高;同时,AAF富含优质碳源,施入土壤后使连作土壤的放线菌数量增加1.57～2.18倍,真菌数量增加2.22～8.43倍,尖孢镰刀菌明显减少,真菌/细菌比值显著提高,尖孢菌/真菌比值显著降低,对枯萎病的防治率最高达80%以上.本研究表明,AAF对连作黄瓜生长具有显著促进和调节作用,对连作土壤微生物活性有激发作用,对黄瓜的连作障碍有明显的缓解作用.但是,从生长趋势看,氨基酸肥料应配合施用一定量的无机肥料,才能使黄瓜持续高产.     

Genetic variation of mitochondrial and nuclear genomes in carrots revealed by random amplified polymorphic DNA (RAPD)

Mitochondrial and nuclear genomic diversities of 8 carrot (Daucus carota ssp. sativus) varieties, including 6 pure lines and 2 cytoplasmic male sterile (cms) lines, were taxonomically identified using PCR with 19 RAPD primers. Dendrograms based on polymorphisms of both mitochondrial and nuclear genomes were constructed. According to the dendrogram of the mitochondrial genome revealed by RAPD, 4 differentiated clusters formed, in good accordance with the classification based on analyses with restriction enzyme digestion. Two cms lines were grouped into the same cluster, as genetically separated from the others. Thus, the cytoplasm donors of these male sterile lines were thought to be wild carrots. Conversely, RAPD analysis of the nuclear genome for these eight cultivars revealed no evident clusters although some cultivars were of a similar origin or place of cultivation. A correlation between nuclear and mitochondrial dendrograms was absent. RAPD has proved to be a useful tool for identifying mitochondrial and nuclear genomes. This technique will greatly aid in promoting efficient improvement of carrots. This revised version was published online in July 2006 with corrections to the Cover Date.     

Helminthosporium leaf blight resistance and agronomic performance of wheat genotypes across warm regions of South Asia

Helminthosporium leaf blight (HLB) is the most important disease constraint to wheat (Triticum aestivum L.) cultivation in the eastern Gangetic Plains of South Asia. A Helminthosporium Monitoring Nursery (HMN) including potential adapted and exotic sources of HLB resistance was developed in Bangladesh, India and Nepal to assess the stability of genetic resistance across locations. The 8th, 9th and 10th HMN assessed the HLB resistance and agronomic traits of 17 wheat genotypes across 20 environments of Bangladesh, India and Nepal in the 1999‐2000, 2000‐2001 and 2001‐2002 cropping seasons, respectively. The area under the disease progress curve (AUDPC) for HLB, grain yield, thousand‐kernel weight (TKW), days to heading, days to maturity, and plant height were examined. The 17 genotypes showed a range of variability for disease and agronomic characters. Disease severity (AUDPC) differed in the 3 years and showed the highest values in 2002. The increase in AUDPC in 2002 caused the lowest grain yield, with an average 18% reduction due to HLB. A few genotypes (SW 89‐5422, Yangmai‐6 and Ning 8201) appeared to have stable HLB resistance across environments. However, most of the higher‐yielding genotypes, except BL 1883, were unstable. The results suggest that careful selection of HLB resistance with acceptable grain yield, TKW and plant height may be possible using the wheat genotypes included in the HMN.     

A rapid technique for determining common root rot reaction in barley

The reaction of two barley cultivars (‘Thibaut’ and ‘Arizona’) and three lines (AECS 76,‘Tadmor’ and WI 2291) to infection by Cochliobolus sativus was evaluated by three methods. Deep seeding of inoculated seeds was performed in pots and field. Gibberellin (GA3) was applied to inoculated seeds in vitro. Susceptibility assessments were made in vitro at 2 weeks, and in pots at 7 weeks after inoculation, using a scale of 1 (very resistant) to 5 (very susceptible) according to the percentage infected area of the subcrown internodes. There were no differences between the results using the three methods.‘Arizona’ was the most susceptible, whereas ‘Thibaut’ and AECS 76 were partially resistant genotypes. The WI 2291 line and ‘Tadmor’ were moderately susceptible and moderately resistant, respectively. In vitro tests yielded the same order as tests from pot and field experiments.     

Genetic variation and response to selection for resistance to root-knot nematodes in oil radish (Raphanus sativus ssp. oleiferus)

Based on a preliminary screening of a collection of cruciferous crops, such as oilseed rape (Brassica napus L. ssp. oleifera Metzg.), oil radish (Raphanus sativus L. ssp. oleiferus DC.), and yellow mustard (Sinapis alba L.), some plants within the oil radish varieties showed resistance to the root-knot nematodes Meloidogyne hapla Chitwood and M. incognita (Kofoid & White) Chitwood. Resistance tests of S₁ progeny of these selected genotypes revealed a quantitative nature of resistance to M. hapla. Only a few resistant individuals were found, but a significant effect of selection was observed. In contrast, the progenies of plants resistant to M. incognita showed a very low number of egg masses, suggesting that this resistance may be conferred by dominant major gene(s). The results indicate that resistance of oil radish to root-knot nematodes may be effective and may thus provide new possibilities for the management of M. hapla and M. incognita.     

厚皮甜瓜衰老过程中保护性酶类的变化

以黄河蜜、银帝、玉金香3个不同品种的厚皮甜瓜为试材,分析测定其在衰老过程中过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)活性的变化情况.结果显示,POD活性与CAT活性变化相似,呈上升-下降-上升趋势,而SOD则呈下降-上升-下降趋势.3种酶活性的高低与品种耐贮性相关,耐贮品种的POD、SOD活性高于不耐贮的品种;而CAT活性则低于不耐贮的品种.     

Identification of male sterility maintainer lines for Ogura radish (Raphanus sativus L.)

‘Ogura radish’, a cytoplasmic genetic male sterile line, was crossed with four local and three Japanese cultivars to identify maintainer lines. Out of seven F₁ families, one cross involving a local cultivar, Aushi, produced 100% male sterile (MS) progeny. The crosses involving the other two local cultivars, Tangail Local and Kuni, produced about 90% MS progeny, indicating the presence of maintainer gene(s) for male sterility. The fourth local cultivar, Tasaki, produced 100% male fertile (MF) progeny. All three exotic cultivars appeared to possess the chromosomal gene(s) for controlling the male sterility. In BC₁, BC₂ and BC₃ generations, segregation of MS plants were more frequent when ‘Aushi’ was used as recurrent parent. The expression of male sterility was not affected by seasonal influences. Thus the local cultivar ‘Aushi’ may be used as maintainer line for ‘Ogura radish’. To produce hybrid seed, ‘Tasaki’ can be used as pollinator line as it exhibit high heterosis with ‘Aushi’. This revised version was published online in July 2006 with corrections to the Cover Date.