贵州城乡二元结构的形成、现状及对策

运用规范研究的方法,从贵州城乡二元结构的形成过程入手,对当前贵州城乡二元结构现状进行分析,统计数据显示,近年来贵州的城乡差距呈不断扩大之势,城乡二元结构日显突出,2005年城乡居民收入比高达4.34∶1,已引起政府和社会各界的高度关注。通过对贵州省的城乡现实状况分析,提出相关对策建议：加大基础设施投向农村的倾斜度;提高农民增收力度和尽快完善涉农相关制度等。     

Tobacco bacterial wilt can be biologically controlled by the application of antagonistic strains in combination with organic fertilizer

Bacterial wilt caused by Ralstonia solanacearum is one of the most serious tobacco diseases worldwide. Brevibacillus brevis (L-25) and Streptomyces rochei (L-9) with strong inhibitory effects on R. solanacearum in vitro were isolated from the rhizosphere of a healthy tobacco plant in a severely wilt-diseased field. Pot and field experiments were conducted to evaluate the biocontrol effect of the isolated antagonists alone and in combination with organic fertilizer. In pot experiment, the control efficacy was 92.3–100 % in the treatments applied with L-25 and L-9 alone or together with organic fertilizers. When bioorganic fertilizer containing L-9 and L-25 was applied to the soil in field condition, the control efficacies were 95.4 and 30.0 in the Anhui and Guizhou field plots, respectively. The counts of bacteria and actinomycetes in rhizosphere soil were significantly increased (p?≤?0.05) under all antagonist applications compared with CK (P_R). In contrast, fungal and R. solanacearum densities in the rhizosphere soil applied with antagonists were much lower than the CK (P_R) rhizosphere. Combined application of the two antagonists had better effect than single antagonist treatments. The antagonists were more effective when they were combined with organic fertilizer as compared with the antagonistic strains only. These results allow us to conclude that a combination of the biocontrol agents, L-25 and L-9, together with organic fertilizers can effectively control bacterial wilt by affecting soil microbial structure.     

烤烟主要化学成分与中间香型彰显度的相关分析

通过对中间香型主要产区的151份烟叶样品检测分析,研究烟叶主要化学成分烟碱、总氮、还原糖、总糖、钾、氯、钾氯比、糖碱比、氮碱比和两糖比等10项指标与中间香型彰显度值的关系。结果表明,当烟碱含量在3.00%左右,钾氯比在12～16之间,糖碱比在6～8之间,氮碱比在0.6～0.8之间,两糖比在0.7左右时,中间香型风格彰显度较高。通过对烟叶主要化学成分和中间香型彰显度值进行回归分析,表明中间香型彰显度值与烟碱和钾含量呈极显著正相关,与两糖比呈极显著负相关。     

硫硼营养对烟叶石油醚提取物合成的影响

硫素和硼素营养对烟叶石油醚提取物的合成起着重要作用。通过田间试验研究硫素、硼素营养对与烟叶石油醚提取物合成有关的6-磷酸葡萄糖脱氢酶、异柠檬酸裂解酶、磷脂酸磷酸酯酶活性的影响及提高石油醚提取物含量的实际效果。试验结果表明,适量的硫、硼营养配合施用对于提高烟叶中石油醚提取物含量有一定的促进作用,当硫素和硼素分别为75、3 kg/hm2时,烤烟不同生育期石油醚提取物含量最高,烘烤后烟叶中部叶石油醚提取物含量为7.84%;6-磷酸葡萄糖脱氢酶、异柠檬酸裂解酶、磷脂酸磷酸酯酶的活性最强。     

发动机润滑系的常见故障分析与处理方法

润滑系技术状况变坏的明显标志是机油压力降低和机油变质,机油压力过低或过高,都说明润滑系工作不良,甚至会造成严重事故。文章从润滑系的常见故障,找出引起故障的原因进行分析,从而对它们进行诊断及排除。     

硫素营养对南江三号烤烟生长及品质的影响

烤烟是需硫量较多的作物,硫素营养与烤烟的生长发育、产量、品质密切相关。研究不同硫水平对烤烟生长发育和产质量的影响。结果表明,增加硫肥的使用,能在一定程度上促进烤烟的生长,处理设计4个硫素水平S0、S1、S2、S3(每667 m2分别施硫0、2.5、5.0、7.5 kg),对烤烟株高、茎围、叶片数、最大叶面积的影响均表现为S3>S2>S1>S0,但增施硫肥对烤烟的生育期并没有产生很明显的影响。说明适量的硫肥能提高烟叶化学品质和中上等烟率,过高和过低硫肥均不利于烤烟产质量的提高。     

血管瘤型禽白血病的实验室诊断

采用血清学方法和分子生物学技术对某蛋鸡场感染鸡进行实验室诊断,采用禽白血病A或B亚群抗体检测试剂盒对该鸡场的血清样本进行检测,抗体阳性率达到70%(7/10);针对ALV群特异性抗原P27基因进行PCR扩增,血液、肝脏病料样本中核酸的检出率分别为66.7%(4/6)、75%(3/4);取ALV 囊膜糖蛋白gp85 基因的扩增产物进行酶切分析,扩增的目的片断中存在BglⅡ和 SspⅠ酶切位点,BamHⅠ不能切割PCR 产物.试验结果证实本次疫病是由ALV-A 亚群病毒引起的血管瘤型白血病.     

小篷竹林分密度初探

小篷竹天然林分密度研究结果表明:随着林分密度的增加,新竹平均地径、株高及小篷竹的出笋率逐渐降低,密度在30 000~45 000株·hm^-2时变化不大;小篷竹的出笋数、成竹数和成竹率先升高后下降,密度为45 000株·hm^-2左右时最高,且与30 000、60 000株·hm^-2区组有极显著差异。综合而言,试验密度为45 000株·hm^-2左右适宜小篷竹的生长发育。     

中国原产果梅自交亲和变异品种花粉决定基因SFB的插入突变

 果梅是配子体自交不亲和树种,但在长期进化过程中也出现了自交亲和品种。以果梅典型的自交不亲和品种‘南高’和自交亲和品种‘甲州小梅’为对照,采用田间自交授粉试验对原产于中国的‘四川白梅’和‘长农17’两个果梅品种进行了自交亲和性鉴定,结果表明：其自花授粉坐果率分别为30.73%和16.27%,属于自交亲和品种。进一步通过AS-PCR分析发现花粉SFB基因存在一段插入序列,造成了分子水平的基因突变。推测该基因的突变使‘四川白梅’和‘长农17’SFB功能发生改变,从而自交亲和。     

Effects of Water Quality on the Distribution of Chinese Giant Salamander (Andrias davidianus) in Guizhou Province,China

13 water quality parameters were tested from 38 reaches of 34 counties in Guizhou where Chinese giant salamander (Andrias davidianus ) distributed over the past 30 years. Dissolved oxygen and pH were found to be significant determinants of the species distribution in recent years (P<0.05). There was no Chinese giant salamander distribution in the recent five years in rivers with dissolved solids of greater than 415 mg/L, conductivity of greater than 639 us/cm, salinity of greater than 0.31 ppt and total hardness of greater than 150 mg/L. Sensitive to environment, the Chinese giant salamander is an important indicator for environmental quality, so it could be used as one of the environmental indicator. Eutrophication, chemical fertilizer, pesticides and inorganic pollutants may be one of reasons driving wild CGS into extinction.