Comparative Performance of Sweet Sorghum Hybrids and Open Pollinated Varieties for Millable Stalk Yield, Biomass, Sugar Quality Traits, Grain Yield and Bioethanol Production in Tropical Indian Condition

Abstract

Sweet sorghum (Sorghum bicolor (L.) Moench) is an important bioenergy crop that has ability to produce both food (grain) and biofuel (from stalk juice). The objectives of the present investigation were (1) to assess the comparative performance of sweet sorghum experimental hybrids with open pollinated varieties (OPVs) for stalk yield, juice sugar quality traits, grain and bioethanol yields, and (2) to identify the best performing genotypes across the locations for both bioethanol and grain yields. Sixteen experimental sweet sorghum genotypes were evaluated during kharif season, 2007 at thirteen tropical Indian locations under dryland condition. Significant (P ≤ 0.05) differences were observed for stalk and sugar related traits. Fresh biomass varied from 39.0 to 67.0 t ha−1 and hybrids as a group produced 11.0 % more than OPVs. Millable stalk yield ranged from 29.4 to 46.5 t ha−1 among hybrids and OPVs with a mean of 40.2 t ha−1. Grain yield ranged from 1.14 to 2.25 t ha−1, and hybrids produced 38.0 % more grain yield than OPVs. Among all test genotypes, SPSSV30 alone recorded significantly superior juice °Brix, and total soluble sugars (TSS) than checks. Juice °Brix content has shown very strong positive correlations (R2 = 0.7956, P ≤ 0.01) with TSS. In total sugar and bioethanol yields (range 1.66–2.53 t ha−1 and 925–1,440 L ha−1, res.), genotypes SPSSH 27, PAC52093 and SPSSH 24 in hybrid group, and SPSSV 20, SPSSV 15 and SPSSV 27 in OPV group were superior. Hybrids have recorded 10.0 and 18.0 % higher sugar and bioethanol yields, respectively than OPVs. The promising OPVs identified from this study could be the potential donors for further improvement of sweet sorghum for biofuel production. The results emphasized the importance of sweet sorghum hybrids over OPVs for stalk and bioethanol yields especially in the future climate change scenario.