缓释肥施氮量对4种国外栎苗木质量及移栽成活率的影响

【目的】探究缓释肥施氮(N)量对4种国外栎苗木生长、矿质养分和非结构性碳水化合物积累及移栽成活率的影响,以期得出4种国外栎1年生容器苗最佳施N量,为培育高品质苗木提供指导。【方法】以夏栎(Quercus robur)、猩红栎(Q. coccinea)、北美红栎(Q. rubra)和沼生栎(Q. palustris)1年生容器苗为试验对象,采用单因素完全随机试验设计,在苗圃期使用缓释肥设置5个水平施N量处理:25、100、150、200和400 mg/株。第1个生长季末测定苗高、地径、生物量、矿质养分及非结构性碳水化合物含量,翌年春季移栽至大田,移栽1 a后测定苗木成活率。【结果】夏栎在施N量200 mg/株时,苗木规格、矿质养分含量和非结构性碳水化合物含量均达到最大值,400 mg/株时生物量显著下降。猩红栎在施N量为150 mg/株时,苗高、地径、生物量和可溶性糖含量最大;200 mg/株时矿质养分积累和淀粉含量最大。北美红栎苗高、地径、生物量和非结构性碳水化合物含量在各处理间均无显著差异,N含量、磷(P)含量随施N量增加而增加。沼生栎地径随施N量增加显著增加,施N量大于100 mg/株后苗高和生物量不再增加,矿质养分含量仍然增加,各处理间非结构性碳水化合物含量差异不显著。移栽1 a后沼生栎的成活率最高(95.0%)、猩红栎的不足30.0%、夏栎和北美红栎的分别为55.0%和45.0%。【结论】夏栎1年生容器苗缓释肥最佳施N量为200 mg/株;猩红栎1年生容器苗缓释肥最佳施N量为150~200 mg/株;北美红栎和沼生栎1年生容器苗缓释肥最佳施N量大于400 mg/株。沼生栎移栽成活率最高,苗圃期适当施肥能增加夏栎、猩红栎和沼生栎容器苗规格和养分贮存,北美红栎养分含量得以提升,但苗圃期施肥对4种国外栎移栽成活率没有显著改善。

Effects of slow-release fertilization rates on seedling quality and field survival rates of four exotic oaks

【Objective】Oaks are widely distributed species which have high ornamental values. This study analyzes the effects of nitrogen rates on seedling growth, nutrient storage, non-structural carbon (NSC) content, and survival rates of four exotic oaks seedlings to explore the optimum nitrogen rate. These information is important for cultivating high quality seedlings of these four oaks. 【Method】 During the first growing season, Quercus robur, Q. coccinea, Q. rubra, Q. palustris seedlings were produced by applying five N fertilization application rates (25, 100, 150, 200 and 400 mg per seedling) by using a slow-release fertilizer. Seedling height, root-collar diameter (RCD), biomass, nutrient content and NSC content were measured at the end of the first growing season. At the beginning of the second growing season, seedlings were transplanted into the field and the survival rate was measured one year later. 【Result】 The height, RCD, biomass, nutrient content, starch content, and soluble sugar content of Q. robur seedlings reached a maximum with 200 mg per seedling applied, while the seedling biomass reduced with 400 mg per seedling applied. For Q. coccinea, height, RCD, biomass and soluble sugar content reached highest values with 150 mg per seedling applied while the nutrient content and starch content reached highest values with 200 mg per seedling applied. For Q. rubra, the nutrient content increased with the increasing of N applied and no significant difference showed in height, RCD, biomass and NSC content. For Q. palustris, RCD content increased significantly with the increasing of the fertilization rate. Height and biomass had no longer increase when N applied more than 100 mg per seedling. The nutrient content increased significantly among the fertilization treatments and no significant difference showed in NSC content. One year after transplantation, the highest survival rates of Q. palustris, Q. coccinea, Q. robur and Q. rubra were 95.0%, 30.0%, 55.0%, and 45.0%, respectively. 【Conclusion】 Based on the results at the first growing season, the optimum N rate for Q. robur one-year-old container seedling is 200 mg per seedling, while 150-200 mg per seedling for Q. coccinea. For Q. rubra and Q. palustris, the optimum N rates are higher than 400 mg per seedling. The survival rates of the four species were not affected by the fertilization treatments.