Variations in infectivity of indigenous rhizobial isolates of some soils in the rainforest zone of Nigeria

Nodule formation in legumes is a process that starts with root infection by rhizobia. The present study assessed the population and infectivity of the indigenous rhizobial strains in rainforest soils of Nigeria. Soils were collected from three sites – Idi-Ayunre, Orile-Ilugun (OI) and the University of Ibadan Teaching and Research Farm (UITRF) – and analysed for physico-chemical properties and rhizobial population. Soybean varieties TGx1448-2E and TGx1456-2E and a cowpea variety IT89KD-288 were planted as trap crops on each of the soils, and rhizobia were isolated from their nodules. Infectivity assay was conducted using eight varieties of soybean and a cowpea variety. Most probable number estimate of the rhizobial population showed that the UITRF had significantly higher rhizobial population than the other two locations. OI and the UITRF soils planted with TGx1448-2E had significantly higher nodules and number of strains than other treatments. Among the 70 slow-grower strains isolated, only nine were infective. Three of the nine strains – IDC8, TRC2 and OISa-6e – nodulated at least seven of the eight soybean varieties used for infectivity test. Indigenous rhizobial infectivity of the studied locations was low, and cultivation of grain legume may require rhizobial inoculation for high productivity.     

Seedling characteristics and retention of current photosynthates in leaves in relation to initial growth in pigeonpea (Cajanus cajan L. Millsp.) and cowpea (Vigna sinensis Endl.)

Improved varieties of pigeonpea (Cajanus cajan L. Millsp.) still retain some growth characteristics of perennial types of wild species such as slow seedling growth and rato on ability which are considered to be major yield-restricting characteristics when the growth period is shortened. Studies on the physiological background of slow initial growth may help improve the potential productivity of short-duration pigeonpea. It was found that the low seedling vigor of pigeonpea could be ascribed to the small seed size (Narayanan et al. 1981; Brakke and Gardner 1987), low rate of photosynthetic CO₂ fixation (Rawson and Constable 1981), and low rates of metabolic processes (Huber and Hanson 1992; Ito et al. 1996). However, few authors have related the slow growth to the retention of current photosynthates and leaf respiration during the night. In contrast, seedling growth of cowpea (Vigna sinensis Endl.) was reported to be vigorous (Brakke and Gardner 1987).

The objectives of this study were to characterize the initial growth of pigeonpea in comparison with cowpea. Two experiments were carried out, one dealing with growth analysis and the other with O2 uptake of leaf and retention of current photosynthates during the night.     

低温对豇豆种子萌发和出苗的影响

[目的]研究低温对豇豆种子萌发及出苗的影响,为华南地区冬种豇豆拒避低温影响提供参考.[方法]以油白1号和粤红5号豇豆种子为试材,在人工气候箱内研究不同温度（10、15、20和25℃）、不同温度组合和不同温度持续时间长短对种子萌发和出苗的影响.[结果]不同温度处理试验结果显示,10℃时两个豇豆品种起始萌发比25℃滞后12～13 d,油白1号的萌发率为33.3％,粤红5号为63.0％;15℃时两个品种起始出苗时间比25 ℃滞后9～10d,油白1号的出苗率为22.0％,粤红5号为18.0％; 10℃时两品种均未能出苗.在低温处理不同时间条件下,10℃低温持续5 d以上种子萌发率显著降低,油白1号为74.1％,粤红5号为44.4％;出苗过程中10℃低温持续2d以上或15℃低温持续5d以上,种子出苗率显著降低.油白1号在相同低温条件下比粤红5号的抗性表现略好.[结论]在华南地区冬种豇豆如果出现10℃低温的天气,或15℃以下低温天气持续5 d以上不宜进行播种;若播种后10℃低温持续2 d以上或15 ℃低温持续5d以上,要采取保温等措施,确保较高的出苗率.     

Effects of tea tree oils on removing pesticide residue in cowpea

为研究茶树油清除果蔬农药残留的效果,该试验选取豇豆为供试材料,以不同浓度的茶树油和水溶性茶树油等清洗处理,利用气相色谱和气相色谱-质谱联用检测豇豆内有机磷类、拟除虫菊酯类和氨基甲酸酯类的农药残留量,计算农药清除率。供试7种农药中,水胺硫磷、马拉硫磷、氧乐果、三唑磷、毒死蜱、氯氰菊酯和速灭威在豇豆中的初始浓度分别为：20.395、1.690、6.524、10.719、0.160、12.104和23.057 mg/kg。茶树油处理后检测结果表明,茶树油具有清除残留在豇豆中农药的能力,清除效果随茶树油浓度增加而增强;清除有机磷类农药效果较拟除虫菊酯类和氨基甲酸酯类农药明显。茶树油比去离子水、市售果蔬农残清洗剂清除农药残留效果显著,同时,相同浓度的水溶性茶树油比相应茶树油清除农药残留能力强。0.8%水溶性茶树油清除效果最佳,清除率分别为水胺硫磷80.48%,马拉硫磷94.54%,三唑磷82.79%,毒死蜱84.58%,氧乐果72.20%,氯氰菊酯80.51%,速灭威72.21%。通过研究结果可知,茶树油可作为有开发前景的果蔬清除剂。     

进境日本豇豆中黑眼豇豆花叶病毒的检测与鉴定

从进口日本豇豆中随机挑选种子在隔离温室内种植。出苗后,发现有典型花叶症状的植株。对该病株进行电镜观测,发现有线条形病毒粒体,大小约为750nm×13nm。设计特异性引物(BL-5/BL-6),对该样品进行黑眼豇豆花叶病毒的反转录(RT)PCR分子检测。电泳检测表明,扩增出一条特异性的目标条带,大小为338bp。对该样品的RT-PCR产物进行测序,结果表明该序列与黑眼豇豆花叶病毒(GENEBANK登录号:AY575773)的序列有4个碱基差异,同源性为98.8%。鉴定该病毒为黑眼豇豆花叶病毒(Blackeye cowpea mosaicvirus)。     

春播区无公害菜用型豇豆栽培技术

豇豆是山西省主要小杂粮作物之一,其中春播区长荚菜用型豇豆面积占山西省豇豆总面积的80%以上,随着国家、政府对食品安全的重视和国民食品安全意识的提高,以及食品优质优价政策的实施,该地区迫切要求科研单位提供无公害长荚菜用型豇豆栽培技术。     

进境豇豆种子携带种传病毒的检测与鉴定

 Imported cowpea seeds were detected with growing test, ELISA assay and RT-PCR method. The ELISA results showed that cowpea seedlings with symptoms reacted positively with antibody against Southern bean mosaic virus (SBMV). The 979 bp of fragment could be amplified from two positive ELISA samples using primers specific for Southern cowpea mosaic virus (SCPMV), and the sequence determination results proved that the pathogen existing in imported cowpea seeds was SCPMV. The positive ELISA results with SBMV antibody could be further confirmed by RT-PCR amplification with specific primers designed to amplify the coat protein gene and 3' noncoding region of SCPMV and SBMV. The RT-PCR method presented here was suitable for molecular identification of SBMV and SCPMV in entry-exit plant quarantine laboratories.     

豇豆愈伤组织诱导的初步研究

研究了不同浓度的生长素(NAA、2,4-D)和细胞分裂素(6-BA、KT)对豇豆[Vigna unguiculata(Linn.)Walp.]花荣下胚轴和子叶愈伤组织诱导的影响。结果表明,子叶较下胚轴更容易诱导出愈伤组织;子叶切片在MS+3.0 mg/L 2,4-D+0.5 mg/L KT中愈伤诱导率最高,为95.83%,下胚轴茎段在MS+3.0 mg/L2,4-D+0.1 mg/L 6-BA中愈伤诱导率最高,为88.89%。此外,2,4-D与KT组合可诱导子叶产生胚状体。     

豇豆种质资源遗传多样性和亲缘关系的SRAP和SSR分析

为从分子水平上揭示豇豆种质资源间的亲缘关系,为其种质资源搜集、鉴定、利用和遗传改良提供一定的理论基础,利用SRAP和SSR分子标记对41 份来自中国和马来西亚的豇豆种质资源进行遗传多样性研究。从65 对SRAP引物和10 对SSR引物中分别筛选获得稳定清晰且多态性强的31 对SRAP引物和5 对SSR引物,对41 份栽培豇豆资源的DNA进行SRAP-PCR和SSR-PCR扩增。2 种PCR扩增共获230 条扩增条带,其中SRAP检测到196 条扩增条带,平均每对引物扩增等位基因数为6.3 条,多态性 片段为161 条,多态性比例为82.14%;SSR检测到34 条带,平均每对引物扩增等位基因数6.8 条,多肽性片段为25 条,多态性比例为73.53%,表明本研究搜集的豇豆种质间的遗传多样性比较丰富。基于SRAP 和SSR 标记的结果,利用UPGMA 构建了41 份豇豆资源的聚类树状图,其遗传相似系数为0.1667~0.9516,大多在0.674 以上。结果表明,SRAP和SSR分子标记能有效地将41 份豇豆资源分开,且部分种质间的遗传距离较远,这为豇豆资源的开发利用及新品种的选育提供科学依据。     

特早熟豇豆新品种夏栽品比试验初报

[目的]探讨特早熟豇豆新品种99-1夏栽的生物学特性及可能性。[方法]对豇豆新品种99-1和当地主栽品种长豆角(CK)两个豇豆品种进行夏栽品比试验。[结果]据两个豇豆品种的植物学特征、生物学特性及农艺性状的品比试验发现,CK营养生长较为旺盛,株高比99-1高约28 cm,叶片数比99-1多。但在荚长、单荚鲜重、每花序结荚数等方面99-1均占优势。前期产量99-1比CK增产62.4%,全期产量99-1比CK增产41.4%。99-1的抗逆性较强,没有发现植株倒伏,早衰现象。[结论]特早熟豇豆99-1比对照品种具有结荚多、产量高、荚形美观、耐热、抗旱、植株不易衰老等优点,适宜夏播,伏缺季节上市,可大面积推广。