Effects of planting date and time of nitrogen application on yield and sugar content of sweet sorghum

This experiment was conducted at Azad University experiment station to evaluate the effects of planting date and time of nitrogen application on yield and sugar content of sweet sorghum in 2003. Four planting dates (May 4, March 19, June 3 and June 18) and three stages of nitrogen application (3-5/8 leaf stage, boot stage and soft dough stage) were assigned to the main and subplots, respectively. Plant height and diameter, fresh stalk yield, total dry weight, brix value (soluble solids), sugar content and grain yield were affected by planting date. For all the characteristics, the maximum value was obtained by the first planting date. Only stem height, diameter and total plant dry weights were affected by time of nitrogen application. In these cases, nitrogen application at (3-5/8) leaf stage was superior to others. According to the results, sweet sorghum should be planted on the beginning of May and nitrogen be applied at (3-5/8) leaf stage.