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| Optimizing the growth and N status of containerized Australian Blackwood (Acacia melanoxylon) seedlings with exponential nitrogen loading |
| Ding Xiaogang,He Qian,Zhang Fangqiu,Li Jiyue,Wei Hongxu,Chen Jing |
| (Guangdong Academy of Forestry;College of Forestry, South China Agricultural University;Province-Ministry Co-construct Key laboratory of Forest
Silviculture and Conservation, Ministry of Education, Beijing
Forestry University) |
| Abstract: |
| Exponential nitrogen (N) loading approach
has been used to optimize seedling growth in container
seedling production. However, the response of seedling
growth to N loading and optimal N loading rates are
species-dependent. There is a lack of information on
optimal N loading in container production of Australian
Blackwood (Acacia melanoxylon) seedlings. In this
study, 7 exponential N loading at rates of 0, 50, 100,
200, 300, 400, and 600 mg N seedling-1, respectively,
were applied at the week 3, 6, 9, 12 and 14 after transplanting to determine optimal loading approach based
on seedling height, root collar diameter (RCD), biomass
accumulation and N uptake in tissue-cultured Australian
Blackwood (A. melanoxylon) seedlings. Seedlings did
not respond to N loading 3 wk after transplanting, then
the accumulative addition of N loading for improved
RCD and seedling height was 12.99 and 28.02 mg N
seedlings-1 in the 100 N and 400 N treatment 6 wk after
transplanting, respectively, and on 9 and 12 wk, that
for improved seedling growth was 63.64 and 400 mg N
seedling-1 in the 200 N and 400 N treatment, respectively. Vector diagnosis of final biomass and N status indicated that the dose of 100 and 400 mg N seedling-1 was
characterized to be "deficient" and "optimum" dose of
exponential N loading for Blackwood seedlings. These
conclusions promise to figure out a precise fertilization
regime for Blackwood seedlings and the demonstration
of dynamic seedling performance could be used for other tree species |
| Key words: Australian Blackwood · Exponential N
loading · Growth performance · Luxury N consumption
· Vector diagnosis |
