Interference of spacing on the growth and biomass of sweet sorghum

The experiment was conducted at the Vale do Curu Experimental Farm of the Federal University of Ceara in Pentecoste in the State of Ceara, Brazil. The aim was to evaluate the interference of spacing in the growth and biomass production of sweet sorghum. The BRS 511 cultivar was analysed in two experiments in a randomised block design; the first, for growth as a function of the inter-row spacing, in a scheme of subdivided plots, and the second, in a factorial scheme, for biomass as a function of planting density. The following variables were evaluated in Experiment I: Plant height (HP), stem diameter (SD), +3 leaf angulation (LA+3), chlorophyll a and b, the chlorophyll a to b ratio and total chlorophyll. The fresh and dry weight of the leaves (LFW/LDW) and the stems (SFW/SDW), and the total fresh and dry weight (TFW/TDW) were evaluated in Experiment II. A reduction in the inter-row spacing resulted in less plant growth; biomass showed higher values at the smallest spacings between rows and between plants. In Pentecoste, an inter-row spacing of 70 cm is recommended for growing the BRS 511 cultivar. For sweet-sorghum biomass, a reduction in plant density to 50 cm between rows and 0.8 cm between plants is recommended to obtain a yield of 250,000 plants per hectare.