钙对爱宕与喜水梨幼苗不同部位矿质元素含量的影响

通过砂培试验,研究了0、16、80、200 mg.L-1 Ca2+处理下1 a生杜梨砧的爱宕和喜水梨苗不同部位(叶、接穗茎、砧木茎与根系)的钙、钾、镁、锌和铁含量的变化。结果表明,不同钙处理下,爱宕与喜水梨叶片钙含量均高于其他部位,且随着钙浓度的增加呈递增趋势;钾含量从高到低依次是叶片、接穗茎、根系与砧木茎,叶片钾含量均以200mg.L-1钙处理相对较低;镁含量均随钙浓度的增加而呈递减趋势,叶片镁含量在品种间无显著性差异,而在0、16mg.L-1钙处理中,喜水接穗茎、砧木茎与根系的镁含量均显著高于爱宕对应值;铁含量以根系最高,且爱宕根系铁含量显著高于喜水;喜水根系锌含量显著高于爱宕,而爱宕的叶片与接穗茎的锌含量相对较高。可见,钙胁迫影响了爱宕与喜水钙、钾、镁、铁和锌等元素的吸收和分配。

接种AM真菌对盆栽梨幼苗缓解Cu2+胁迫的影响

以黄冠/川梨为材料,以幼套近明球囊霉为菌剂,采用盆栽方式,研究接种AM真菌对梨幼苗缓解Cu^（2＋）胁迫的影响。结果显示：在铜浓度为0~400mg/kg范围内,重金属Cu^（2＋）对梨的营养生长和生理抗性表现出了显著的低促高抑的效应,在低浓度（≤150mg/kg）情况下,对梨幼苗有促进作用;在高浓度（〉150mg/kg）时,对梨幼苗有抑制作用,且在150mg/kg的情况下促进作用最好。从处理组与对照组对梨幼苗生长指标、光合作用指标、叶片保护酶活性、渗透调节物质含量等因素的综合影响来看,在不同处理下,接种AM真菌有利于提高植株的各项生理指标且均显著高于对照组。试验还发现所用的AM真菌能有效地侵染梨的幼苗,这对缓解Cu^（2＋）胁迫起到了重要作用。

Pre-seed Treatment Effects on Avocado （Persea americana L.） Seedlings Health and Growth before Side-Grafting in Ghana

Studies were conducted to detennine the effects of hot water （50 ℃） and fungicide （contizeb ‘5＇） treatments on avocado seeds in terms of seed health, germination and seedling growth before side-grafting. The leathery coverings or seed coat were removed and either 1 cm or 1.5 cm of the narrow top of the seeds was removed before sowing. There were six treatments arranged in a randomized complete block and rephcated three times. In a six week period after germination when side grafting could be done, it was found out that the earliest germination came from the ＇no hot water or fungicide-treated＂ seeds cut at 1 cm but most seeds germinated from the fungicide-treated seeds at 1 cm cut. Most fungi including Fusarium andAspergillus spp found to either delay germination or reduce seedling vigour were minimized in number through the fungicide treatment compared to the hot water-treated seeds. Seedlings performance in terms of shoot extension and canopy development was significantly better in the fungicide-treated seeds than from either the hot water or the non-treated seeds. The study concluded that avocado seed treatment prior to sowing enhanced germination.