Efisiensi Pemanfaatan Radiasi Surya Pada Tanaman Soba (Buckwheat) Di Iklim Tropis Vol 7, No 2, 2001

Abstract

The study has been conducted to determine radiation use efficiency of buckwheat (Fagopyrum esculentum Moench.) in tropical climafe. Experiment site of Ciawi. Bogor was located at 400 m above sea level. A cultivar of kitawase was grown under three population densities, viz. P1 (200 palis/ m2). P2 (160 palts/ m2) and P3 (130 palts/ m2). Sowing dates were on April, May and June 2000. Radiation intensity, air temperature and soil temperature were measured. While agronomic variables were observed for dry matter production, yield components ond yield. Photasynthetic rates of leaf upper and below canopy were determined. The results suggested that during the period of emergence to fifth week after sowing, the higher of population has the higher radiation use efficiency. Entered to sixth week, the higher population tend to be lower in efficiency. Those phenomena indicated rhar during seed filing and ripening period, radiation use efficiency were more intensive at lower population. Nevertheless, the grain yield was characterized by population density, namely P1 (172 g/ m2), followed by P2 (144 g/ m2) and P3 (124 g/ m2). The photosynthetic rate of upper leaf was 12 μmol CO2/ m2/ s at PAR of 1900 μmo/ m2/s, whilefor leaf below the canopy with PAR of 750 μmol/ m2/ s the rate reached only 9 μmol CO2/ m2/ s. The photosythetic rates of lower leaves were great influenced by plant population densities which arranged different radiation environmental respective level.