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Determination of Nitrogen and Phosphorus requirements of Large Leaf Mahogany (Swietenia Macrophylla King.) Seedlings
Thesis Abstract:
Nitrogen and phosphorus requirements of large leaf mahogany seedlings were determined using the sand culture technique. The study aimed to determine the treatments that will give the best height, diameter, shoot, and root developments of seedlings; to know the critical level for nitrogen and phosphorus; and to know the deficiency symptoms exhibited by the seedlings if any of the two elements was absent.
The experiment was arranged in a 4 x 4 (N x P) factorial in a completely randomized design with three replications. There were four levels of nitrogen (from urea with 45 N) and four levels of phosphorous (from superphosphate with 18 P). These levels were combined, resulting in 16 treatment combinations. Fifteen experimental seedlings were assigned for every treatment (5 seedlings per replicate).
Results showed that nitrogen significantly improved the height and diameter growth of large leaf mahogany seedlings. Biomass was also improved by nitrogen application. Nitrogen levels ranging from N0.5 to N15 per seedling was best for height, diameter, growth, and biomass production of the seedlings. The critical level of nitrogen for height and diameter was 0.83 percent. The growth and development of the seedlings were impaired in the absence of nitrogen. Nitrogen produced top heavy seedlings. Furthermore, it was observed that seedlings deprived of nitrogen exhibited pale and yellow leaves.
Phosphorus, on the other hand, did not significantly improve the height and diameter growth as well as biomass production of large leaf mahogany seedlings. The absence of phosphorus had a little retarding effect on the development of large leaf mahogany seedlings. It was further observed that the leaves turned to dark green and bluish color.