云南省天然橡胶技术标准体系发展现状及对策

论述橡胶技术标准体系在提高云南省橡胶产品市场竞争力、增收增效中的地位和作用,分析云南省橡胶标准化体系的现状及存在问题,并提出建立健全橡胶技术标准化体系的对策与建议。     

Vegetative compatibility groups and parasexual segregation in Colletotrichum acutatum isolates infecting different hosts

Heterokaryosis is an important mechanism which provides genetic variability increase in filamentous fungi. In order to assess the diversity of vegetative compatibility reactions existing among Colletotrichum acutatum isolates derived from different hosts, complementary nit mutants of each isolate were obtained and paired in all possible combinations. Vegetative compatibility groups (VCG) were identified among the isolates according to their ability to form viable heterokaryons. Seven VCGs were identified among the isolates, one of which contained isolates from different hosts. VCGs 2 and 6 contained two and three members, respectively; VCG-3 contained four members, and four VCGs (1, 4, 5, and 7) contained a single one. This study shows, for the first time, the isolation and the parasexual segregation of a heterozygous diploid sector derived from the heterokaryon formed with nit mutants from VCG-6. Diploid, named DE-3, showed nit+ phenotype and growth rate similar to the parental wild isolate. When inoculated in the presence of the haploidizing agent benomyl, the diploid strain produced parasexual haploid segregants exhibiting the nit phenotypes of the crossed mutants. Since viable heterokaryons and diploid may be formed among vegetative compatible isolates of C. acutatum, this study suggests that the parasexual cycle may be an alternative source of genetic variability in C. acutatum isolates.     

蔗叶不同还田模式对土壤水分和甘蔗产量的影响

田间试验研究了蔗叶不同还田模式对旱地蔗园土壤水分和甘蔗产量的影响。结果表明,蔗叶不同还田模式的甘蔗产量差异不显著,蔗叶全覆盖还田与蔗叶隔行覆盖还田处理的总苗数较焚烧处理差异达极显著性水平（P〈0.01）,有效茎与焚烧处理差异达显著性水平（P〈0.05）。蔗叶全覆盖还田与蔗叶隔行覆盖还田对宿根蔗垄上前期与后期的土壤水分保持效果较好,不同蔗叶还田模式对甘蔗行间的土壤水分保持效果较好。