Effect of Plant Density and Row Width on Canopy Architecture in Sorghum

Abstract

Plant architecture can be used to simulate resource acquisition, biomass production and plant stand levels thus increasing resource capture efficiencies to be compared between architectures. In the present study, five biofuel sorghum genotypes and one maize hybrid were grown at two planting densities (20 plants/m² and 30 plants/m³) and two row width (40 cm and 67 cm). The elevation angle, phyllotaxy and blade curvature orientation were monitored using 3 D Polhemus digitizer and the shoot organ characteristics (leaf area, leaf length, leaf area index, total biomass) were monitored by destructive measurements. Leaf area indices calculated from destructive measurements were compared with those of nondestructive measurements using the LA12000 device (Licor, Lincoln, USA). Variation of plant density caused significant changes in architectural traits like leaf area index (LAI) and total hiomass. From early stages of crop growth, leaf elevation angle and leaf to leaf angle were markedly affected by treatments, with the measured leaf length showing a strong correlation (r=0.85) with the digitized leaf length. An interaction between plant width and population density on total biomass of the crops was determined for one genotype (S. bicolor S. sudanense) displaying the highest biomass and leaf area index (LAI) under all conditions. Significant difference was detected on the leaf fresh weight, leaf dry weight, and mean leaf tip angle across the canopy strata of the different plant densities and row widths for mean comparison at Tukey test P≤0.05. Significant interaction of row width and density was observed when plant densities of 20 plants/m² and 30 plants /m³ were used. Increasing row width from 40 cm to 67 cm led to an increase in total dry weight. One genotype gave a desirable architectural trait which can be used as an excellent target for genetic selection to enhance yields.