A preliminary investigation into agroforestry practices in the savanna belt of western Nigeria

This paper evaluates agroforestry practices in a part of the Guinea savanna belt of south-western Nigeria. The attitude of local farmers to tree planting in crop fields was evaluated. Tree adoption on the farm was assessed by identifying the tree species on the field and their frequencies. The results show that there is little indication that the trees are deliberately utilized to enhance farm operations in the area. It is concluded that greater attention needs to be given to the promotion of agroforestry techniques in the savanna belt. This is especially important as the increasing demand for food would put pressure on the soil resources.     

块状紫山药新品种苏蓣3号的选育

苏蓣3号是通过辐射诱变育种的方法,由"浙江余杭紫莳药"品种突变而获得新品种。其生育期中等偏迟,平均160~180 d。以块茎作种薯,一般播后40~45 d出苗,苗势壮。块茎纺锤形,表皮褐色,肉质柔滑,紫色亮丽,块茎肥大。块茎直径10~13 cm、长15~18 cm,单株结1~3块,单株块茎质量1.0~1.5 kg,少结零余子。     

不同浓度赤霉素对山药种薯发芽的影响

为探讨适宜用于破除山药块茎休眠的赤霉素(G A3)浓度,以福建地方山药品种"六月薯"为试验材料,设不同浓度(0、100、200 m g/L)的G A3处理,比较其对块茎休眠的影响.结果表明:100、200 mg/L GA3处理均能快速且显著提高块茎内源GA3含量,显著改变茎段的休眠强度和休眠幅度,休眠强度分别缩短了7....     

热水处理对薯蓣红斑病病原——咖啡短体线虫的影响

采用水浴法,对离体咖啡短体线虫、薯蓣块根内咖啡短体线虫以及薯蓣块根在不同温度条件下的敏感性进行测定。结果表明,在47、50、52、55 ℃处理条件下,杀死100%离体咖啡短体线虫的处理时间分别为6、2.5、1.5、1.5 min,而杀死100%薯蓣块根内线虫的处理时间分别为19、15、11、10 min;同时在上述温度下,分别处理35、30、25 min和25 min对薯蓣发芽没有影响。在同一温度处理中,随着处理时间延长,线虫的死亡率增加;而在不同温度处理中,随着温度升高,杀死线虫的时间逐渐缩短。综合上述试验结果,建议生产上防治薯蓣种薯内咖啡短体线虫的处理方法以52～55 ℃处理15～20 min为宜。     

山药多糖的化学分析及其生物活性

参考我国近5年来关于山药多糖的研究成果,列举了其提取分离技术,分析了其单糖组成和摩尔比,综述了其抗氧化、抗肿瘤、抗衰老、降血糖等生理活性,并对其今后的研究方向作了展望。     

菏泽鸡皮山药中氨基酸含量的测定

[目的]测定菏泽鸡皮山药中的氨基酸含量,为菏泽鸡皮山药的资源开发提供科学数据。[方法]鸡皮山药采自山东省菏泽市城郊农村,长根状,直径1.6~2.9 cm,样品经酸解处理后用氨基酸分析仪测定其氨基酸组成。[结果]菏泽鸡皮山药中含有19种氨基酸,种类齐全,总量达19225.1 mg/kg;其中含有8种人体必需氨基酸,分别为苯丙氨酸、蛋氨酸、赖氨酸、亮氨酸、色氨酸、苏氨酸、缬氨酸和异亮氨酸,总量为6763.0 mg,占总氨基酸含量的35.18%;还含有婴儿必需氨基酸精氨酸与组氨酸,含量为3688.5 mg,占氨基酸总量的19.19%。[结论]菏泽鸡皮山药中必需氨基酸总量所占比例较高,在医学和营养学上具有很高的研究价值。     

Jamaican Bitter Yam Sapogenin: Potential Mechanisms of Action in Diabetes

Sapogenin has been proposed to be the active component responsible for the beneficial effects of Jamaican bitter yam (Dioscorea polygonoides) in the management of diabetes. Most of the research activities on bitter yam have focused on the role sapogenin play in the management of diabetes. Changes in weight, activities of carbohydrate digestive and transport enzymes, alterations in the intestinal morphology, changes in blood lipids, reduction in lipid peroxidation and the prevention of liver damage associated with diabetes have all been attributed to bitter yam sapogenin supplementation. Also, the possible exploitation of bitter yam for nutraceutical/pharmaceutical purposes is based on the high saponin content. There are however, concerns about the beneficial claims of the findings especially with regard to the possible adverse effects that may accrue in the clinical applications. This review therefore provides an overview of the findings in this research area with a view to proposing the potential mechanisms whereby the supplement of bitter yam sapogenin extract exert its hypoglycemic and hypolipidemic properties and the probable adverse effects in diabetes mellitus.     

Using isozyme polymorphism to assess genetic variation within cultivated yams (Dioscorea cayenensis/Dioscorea rotundata complex) of the Republic of Benin

Four hundred and sixty-seven accessions of cultivated Guinea yam (Dioscorea cayenensis/Dioscorea rotundatacomplex) collected from different localities of Benin Republic were analysed to study isoenzymatic variability in seven enzyme systems: aspartate aminotransferase (AAT), esterase (EST), glucose-6-phosphate dehydrogenase (G6PDH), isocitrate dehydrogenase (IDH), phosphoglucomutase (PGM), phosphoglucoisomerase (PGI), and shikimate dehydrogenase (SKDH) using starch gel electrophoresis. Polymorphism was observed in all of the enzyme systems and a total of 62 electromorphs of different frequency and variability patterns were recorded. Different combinations of banding patterns of these systems led to identification of 227 different cultivars within the 467 accessions analysed. For an old and vegetatively propagated crop (with a considerable number of vernacular names) such as yam, and for which a high rate of duplication is expected, the 227 cultivars were found to be good enough to be considered as the adequate number of accessions representing the diversity in the germplasm analysed. Cluster analysis (UPGMA) produced a most likely division of the 467 accessions into two groups corresponding to D. rotundata Poir. and D. cayenensis Lam., supporting the concept that the two forms of guinea yam represent different genetic entities. The different clusters formed within the white yams (D. rotundata) did not exactly conform to the known cultivar groups. Additional polymorphic enzymes are needed for an accurate isozyme-based genetic discrimination of most of the cultivar groups.     

Identification of some Benin Republic's Guinea yam (Dioscorea cayenensis/Dioscorea rotundata complex) cultivars using Randomly Amplified Polymorphic DNA

DNA from twenty-three late maturing cultivars of Guinea yams (D. cayenensis/D. rotundata complex) from the Benin Republic that could not be separated using isozyme markers, were examined using randomly amplified polymorphic DNA (RAPD) markers with decamer primers of arbitrary sequence. All the twelve primers tested were informative and yielded 63 amplified DNA bands from which 47 (75%) were polymorphic. Although no single primer produced polymorphic bands in all cultivars, the great majority of the cultivars were separated with the combinations of polymorphic bands generated by various primers. Putative duplicates and cultivar misclassifications were identified. Many morphologically distinct cultivars were close. The dwarf cultivar Tam-Sam considered as derived from Tabane, appeared more distant from the latter than was believed. RAPD analysis was found as a practical tool for the identification of duplicates toward establishment of an accurate core collection of Guinea yams in Benin Republic and in the other countries of the African yam belt.