Japanese Journal of Tropical Agriculture

Photosynthetic characteristics of coffee leaves developed under various shading levels (0, 30, 50 and 80%) were examined.
The net photosynthetic rate above 150μmol m^-2s^-1 PPFD was the highest in unshaded plants, and it declined with increasing degree of shading. Saturation and compensation irradiances of photosynthesis and dark respiration also declined with shading.
The net photosynthetic rate was highest at 20°C and relatively high within the range from 15 to 25°C irrespective of the treatments. The rate of photosynthesis declined above 25°C and the reduction was the greatest in unshaded plants. The difference in net photosynthetic rate among shaded and unshaded plants at higher temperatures was assumed to be associated with increased dark respiration.

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The kinetics of hydrolysis of giant ipil-ipil wood was studied in dilute sulfuric acid of different concentrations, C (%) at various temperatures, T (K) . The first-oder rate constants, k_A, k_B and k_C were obtained for the pentosan fraction easy to hydrolyze, the pentosan fraction difficult to hydrolyze and the cellulose fraction, respectively.
k_A=1.94×10¹³⋅C^1.20⋅exp (-113000/ (RT) )
within the range of C=0.5-2.1% and T=393-413 K
k_B=2.82×10⁹⋅C^1.32⋅exp (-91600/ (RT) )
within the range of C=0.5 -2.1% and T=393-413 K
k_C=6.28×10¹⁸⋅C^1.17⋅exp (-175000/ (RT) )
within the range of C=0.4-1.6% and T=443-463 K
where R is the gas constant (J⋅mol^-1⋅K^-1) .
Xylose and glucose yields calculated by use of these values were in good agreement with those recorded in the experiment.
These rate constants are comparable to those of another hardwood which have been studied on dilute acid saccharification.

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The pyrolysis rates of giant ipil-ipil lignocellulose and cellulose were determined. The rate constants were correlated with temperatures ranging from 325 to 375 °C under vacuum. The levoglucosan yields from lignocellulose and cellulose could be predicted from the correlations.

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Three experiments on the effects of day/night temperatures on the devernalization process were conducted. The combination of day and night temperatures ranged from 5°C-30°C, with treatment periods of 21, 30, and 40 days. Day and night temperatures demonstrated similar actions on the devernalization effect. In‘Minowase’radish, the temperature as high as 15°C was found to provide a vernalization effect. The range of day temperatures for devernalization was 17°C-30°C, with 17°C being the minimum day temperature for devernalization and 30°C being the day temperature necessary for complete devernalization. Techniques of increasing vernalization ability in tropical areas were discussed.

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