Determining leaf area coefficient for speargrass (Imperata cylindrical) in controlled environment studies

Abstract

Calculated leaf area (length x width) and directly measured leaf area (from leaf area meter) of the main and secondary shoots of screenhouse-grown speargrass from the derived (DS, Ibadan), southern Guinea (SGS, Ilora) and northern Guinea (NGS, Bida) savanna agro-ecozones in Nigeria, were compared using regression analysis to determine coefficients for estimating leaf area from linear leaf measurements. Leaf length, leaf width and actual leaf area were measured in non-senescent fully-expanded leaves, randomly selected from 14 week-old speargrass developed from 2 cm rhizome sections. Calculated leaf area and directly measured leaf area were on the average significantly (P<0.001) and highly correlated in both the main (r= 0.98) and secondary (r= 0.99) shoots of speargrass from different locations. Coefficients for main shoots of speargrass from both DS (b₁= 0.67) and SGS (b₁= 0.69) were significantly (t< 0.05) higher than in speargrass from NGS (b₁= 0.55), whereas no significant difference was found in coefficients for secondary shoots of speargrass from different locations (b₂: DS= 0.66; SGS= 0.66; NGS= 0.64). Differences between pairs of coefficients for secondary shoots were related to actual leaf size. The minimum number (n) of leaves required to obtain reliable coefficient were 10, 40, and 109 respectively for main shoots, and 36, 50, and 37 for secondary shoots of speargrass from DS, SGS, and NGS. Regardless of location, secondary shoots of speargrass required a higher n than main shoots.

Key words: Leaf area coefficient; speargrass; controlled environment

Moor Journal of Agricultural Research Vol.4(2) 2003: 198-205