Effect of nitrogen and row spacing on growth, yield and quality of sugarcane (Saccharum officinarum) varieties

A field experiment was conducted during the main crop seasons of 1992-94 on sandy-loam soil at Coimbatore, to study the response of 2 early ('Co 85002' and 'Co 85004') and 3 mid-late ('Co 86027, 'Co 86032' and 'Co 86038') sugarcane (Saccharum officinarum L.) varieties to 5 levels of N (0, 100, 200, 300 and 400 kg/ha) and 2 row spacings (75 and 90 cm). The number of millable canes, juice-quality characters, yield and yield attributes differed significantly due to row treatments. But row spacings within the variety did not influence the cane and sugar yield. However, increased planting density at 75 cm, spacing resulted in higher cane and sugar yield in 'Co 85002', 'Co 86032' and `Co 86038'. The different levels of N influenced significantly the number of millable canes, leaf-sheath moisture, cane and sugar yield, but the juice quality was unaffected. The highest cane and sugar yields were recorded at 300 kg N/ha. There was a slight reduction in purity (%) in early varieties at 400 kg N/ha. Significant positive correlation was found between leaf-sheath moisture at formative phase and final cane yield. Quadratic responses to N levels were found significant and based on multiple-regression equation the optimum N ranged from 239 to 300 kg/ha for different varieties.