Pantipa Na Chiangmai and Phakatip Yodmingkhwan

pp. 685 - 692

Abstract

This study aimed to evaluate the effect of phosphorus application on shoot biomass, root biomass, and shoot/root
biomass ratio of common wild rice (Oryza rufipogon Griff.) and two tropical cultivated rice (O. sativa L.) varieties, including
Sew Mae Jan (an upland rice) and KDML105 (a lowland rice), under two levels of inorganic phosphorus application (0 mg
P/l and 10 mg P/l) both in monoculture (specific variety growing) and mix-culture (genetic competition setting) at early stage
of growth (about 45 days after planting). Results indicated that phosphorus availability at 10 mg P/l clearly affected both rice
shoot and root biomass at early growth stage. Significant interaction effect was found between phosphorus levels and rice
varieties both above- and underground tissues accumulating in mix-culture of rice varieties. O. rufipogon showed a response
to phosphorus application when shoot and root dry weight accumulation was assessed. Sew Mae Jan and KDML105 did not
show any significant difference on shoot biomass accumulation when grew under mix-culture condition. The relative interaction index (RII) of O. rufipogon showed highly competitive response for accumulating both on shoot and root biomass
compared with Sew Mae Jan and KDML105.