GROWTH AND PHOTOSYNTHETIC RATE RESPONSES OF SHOREA PLATYCLADOS

GROWTH AND PHOTOSYNTHETIC RATE RESPONSES OF SHOREA PLATYCLADOS SEEDLINGS TO NITROGEN APPLICATION ONG KIAN HUAT, LIM MENG TSAI & ABDUL LATIB SENIN

Introduction Shorea platyclados – montane species can be found in Borneo, Peninsular Malaysia and Sumatra. Usually found at elevations between 800 and 1, 000 m, in upper hill dipterocarp forest zone, where Shorea curtisii usually begins to disappear. Timber is light hardwood of dark red meranti group. Relatively fast growing species.

Growth rate of Shorea platyclados No. Site Age MAI – diameter (cm yr-1) MAI – height (m yr-1) Source 1 Pahang, Malaysia 27. 5 1. 26 1. 13 Vincent (1961) 2 Kepong, Malaysia 26. 5 1. 63 1. 13 Vincent (1961) 3 Bogor, Indonesia 25. 0 1. 64 1. 00 Masano & Harun (1991) 4 North Sumatra, Indonesia 37. 0 1. 03 - Butarbutar & Supriana (1988)

Introduction … continue Fertilizing is common produce healthy and specified period of time. practice sizeable in nursery seedlings to in However it rarely based on any quantitative knowledge of requirements of species. Photosynthesis is an important determinant of growth.

Objective to determine effect of N supply on growth and net photosynthesis of S. platyclados seedlings

Materials and Methods Potting medium – 7: 3: 1 mixture of topsoil, sand peat. 8 month-old seedlings, seeds collected from trees along Tapah to Cameron Highlands road. Uniform seedlings in terms of height were transplanted into 7. 7 L pots. Experimental design – block. randomized complete

Materials and Methods … continue Four urea treatments: 3 g (U 3), 6 g (U 6), 9 g (U 9) and control. Fertilizer applied 1 month after repotting. Experiment was conducted for 3 months. Treatments were applied over 3 separate occasions over 2 months.

Operations schedule for application of fertilizers of Shorea platyclados Application rates Beginning 1 st month 2 nd month Without fertilizer (Control) - - - 3 g urea 3 g - - 6 g urea 3 g 3 g - 9 g urea 3 g 3 g 3 g

Results and Discussions Nutrient addition had significant affect on height and collar diameter growth, and dry matter production. Urea resulted in increase in leaves and stem N concentration. Photosynthetic rate increased with foliar N concentration

Height increments for seedlings of Shorea platyclados

Dry weight and root/shoot ratio of Shorea platyclados Treatment Leaf (g) Stem (g) Root (g) Total (g) R/S ratio Control 4. 74 c 3. 84 b 6. 16 b 14. 74 c 0. 71 a 3 g 15. 30 a 13. 69 a 14. 24 a 43. 23 a 0. 50 b 6 g 11. 78 b 10. 54 a 10. 58 a 32. 89 b 0. 47 b 9 g 12. 38 b 11. 14 a 12. 26 a 35. 78 ab 0. 53 b

Nitrogen concentration in Shorea platyclados components Treatment Leaf (mg g-1) Stem (mg g-1) Root (mg g-1) Control 10. 24 c 2. 68 c 6. 85 a 3 g 14. 55 b 3. 37 b 7. 21 a 6 g 16. 35 a 4. 35 a 6. 83 a 9 g 15. 37 ab 3. 39 ab 7. 25 a

Photosynthesis rates of Shorea platyclados in relation to foliar N concentration

Conclusions Growth and photosynthetic rate of S. platyclados seedlings was promoted by fertilizer. 3 g of urea – optimal enough for improving growth and nutrition of S. platyclados seedlings. Improved in growth may due to increases in leaf area and photosynthetic rate as a result of higher foliar N concentration. Higher foliar N concentration was not a good predictor of S. platyclados seedling growth.

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