Sorghum Vegetative Growth and Development Pattern Under Different Nitrogen Fertilization.

Improving biomass yield of Sorghum (Sorghum bicolor L) is important because of its uses as feed and biofuel feedstock. Over the past two years, two sorghum types– ES 5200 (high biomass sorghum) and EJ 7281 (sweet sorghum) were planted at the Agriculture Research Station of the Fort Valley State University, with no nitrogen and 90 kg ha^-1 N in a randomized complete block design.  The parameters of importance to biomass production consisting of plant height, leaf senescence, leaf area index, chlorophyll content and rate of photosynthesis were measured throughout the growth period, at two week intervals starting with the “Final Leaf Visible in Whorl” stage ( stage 4) of sorghum growth.  Plant height and plant biomass increased significantly with season in both years (2012 and 2013) for the two genotypes. Biomass production for genotype x nitrogen interaction was also significantly different for the different weeks after planting (WAP).  At the end of the season, the amount of biomass produced by sweet sorghum was greater than forage sorghum but the variation was not statistically significant. The results indicated that forage and sweet sorghum reacted similarly with or without nitrogen treatment for biomass production.