Abstract

Plant architecture is of major agronomic importance as it determines the potential grain yield depending on environmental conditions in rice (Oryza sativa L.). Here, we characterized plant architecture and its response to low fertilizer and high planting density in five rice “reduced culm number (rcn)” mutants; “rcn1-2, rcn2, rcn4-2, rcn5and rcn6”, originating from rice cultivar ‘Shiokari’, with ‘Shiokari’ as a parental control. Under control condition, a positive correlation was observed between tiller number and plant height showing that each rcn controls both apical and axillary shoots elongation. High density and low fertilizer had the negative effects on tillering and main shoot development involving main culm length, leaf number, panicle length, spikelet number on main culm in ‘Shiokari’. The degrees of negative effect on main shoot development by the present environmental stresses were depended on ‘rcn’ genotype. Among them, ‘rcn6’ constantly developed main shoot architecture under low fertilizer or high density planting.

Key words: Tillering, reduced culm number mutant, low fertilizer, high density, rice.