Productivity and profitability of different genotypes of sugarcane (Saccharum spp. hybrid complex) as affected by fertility levels and planting seasons

A field experiment was conducted for three consecutive years (2007-10) on calcareous soil at Pusa (Bihar) to evaluate 3 sugarcane ( Saccharum spp. hybrid complex) midlate genotypes (BO 147, BO 146 and CoP 022) at 3 levels of fertilizer viz; 75% RDF, RDF (150 kg N + 37.1 kg P + 49.8 kg K/ha) and 125% of RDF in two seasons (autumn and spring). Higher growth, yield attributes and cane yield in terms of tillers (170.4 and 149.3 thousand/ ha), cane length (211 and 204 cm), total dry matter accumulation (33.2 and 30.0 t/ha), number of millable cane (112.0 and 109.6 thousand/ha), cane yield (82.9 and 75.2 t/ha) and sugar yield (9.6 and 8.5 t/ha) were recorded in BO 147 in autumn and spring season, respectively. However, genotype BO 146 showed significantly higher val- ues of brix and pol % juice across the planting season. Nutrient uptake followed the yield pattern of the varieties. Genotype BO 147 gave higher net returns and benefit: cost ratio across the season. Significantly higher tillers (158.5 and 140.8 thousand/ha), cane length (213 and 208 cm), dry matter accumulation (33.9 and 30.9 t/ha), cane diameter (2.38 and 2.18 cm), number of millable canes (107.1 and 105.0 thousand/ha) and cane yield (86.0 and 79.9 t/ha) were obtained with the application of 125% recommended dose of fertilizer in autumn and spring sea- son, respectively. Though all of these parameters except dry matter in both the season and cane diameter during spring season were statistically similar to 100% RDF. Autumn planted sugarcane recorded 9.8 and 11.1% higher sugar over spring planted sugarcane. Nutrient uptake increased significantly with each successive increase in fer- tility level upto 125% RDF, resulting in 59.6; 53.2% increase in N uptake, 46.9; 51.2% increase in P uptake and 48.5; 50.9% increase in K uptake due to application of 125% RDF over 75% RDF during autumn and spring sea- son respectively. Similarly, the available N, P and K content of soil was found to be higher due to the enhanced levels of applied nutrients to the soil. Significant increase in net returns was obtained by increasing levels of N, P and K during both the seasons. Sugarcane BO 147 can be grown for higher sugar yield and economic returns with application of 187.5 kg N + 46.4 kg P + 62.3 kg K/ha (125% RDF) during autumn as well as spring season.