| Registro completo |
| Provedor de dados: |
Ciências Agrárias
|
| País: |
Brazil
|
| Título: |
Índice de área foliar de Eucalyptus grandis em resposta à adubação com potássio e sódio
|
| Autores: |
Almeida, Julio Cesar Raposo de
Laclau, Jean-Paul
Gonçalves, José Leonardo de Moraes
Moreira, Rildo Moreira e
Rojas, Juan Sinforiano Delgado
|
| Data: |
2007-10-24
|
| Ano: |
2007
|
| Resumo: |
Leaf Area Index (LAI, i.e. horizontal projection of leaf area per unit ground area) is highly correlated with water balance and net primary production in forest ecosystems. LAI is related with species, but it is also highly dependent on environmental conditions and management practices which influence the availability of water and nutrients. This work aimed at establishing allometric relationships in fast-growing Eucalyptus grandis plantations in Brazil (Itatinga – São Paulo) making it possible to predict the LAI under K and Na fertilization. Dendrometric inventories (Crown diameter – CD, Diameter at Breast Height - DBH and total height - H) were made at 5, 8, 11, 24 and 35 months after planting. The trees were divided into 8 crown index (CI) or basal area (g) classes per treatment. One representative tree in each class was felled at ground level and sampled for leaf area determination at each age. The biomass and the specific leaf area (SLA = cm2 g-1) were determined in 3 parts of the crown of equal length (bottom, middle and top). The data were used to establish a regression (Proc NLP, SAS) between CI, DBH and H and the total leaf area per tree. The equation was applied to all the trees inventoried at the same age, and the sum of total leaf area per plot was divided by the plot area. The comparison of local models (established individually for each treatment) with global models (for the trees sampled in different treatments) showed that global models were more adapted over the early growth of the stands (5, 8 and 11 months of age). By contrast, locals models were more accurate at 24 and 35 months after planting (AIC and BIC procedures). Throughout the 35 months of growth, the mean SLA for all the treatments decreased. However, the fertilization regimes modified leaf structure at 35 months after planting. Whereas the commercial K application led to a mean SLA of 119,4 cm2 g-1, Na application led to a decrease in SLA of 22% and 5,7% without K and Na application (control). The leaf area index was highly modified by fertilization regimes. The LAI increased continuously under K application to reach 5,40 at age 35 months. At age 11 months, Na application led to a LAI 39% higher than in the control treatment, but the differences were no more significant at 24 and 35 months after planting, LAI values stabilized around in almost 3. Therefore, K fertilization enhanced the LAI by a factor of about 2 over the first three years of growth in this Eucalyptus grandis plantation and Na fertilization did not increase significantly the LAI from age 1 year onwards.
|
| Tipo: |
Article
|
| Idioma: |
Português
|
| Identificador: |
1982-1751
http://hdl.handle.net/2315/82
|
| Relação: |
1/2007
|
| Formato: |
284234 bytes
application/pdf
|
|
