Nitrogen response and water use efficiency of sweet sorghum cultivars

Abstract

Sweet sorghum [Sorghum bicolor (L.) Moench] is a biofuel crop, which can be grown under tropical rainfedconditions without sacrificing food and fodder security. Three sweet sorghum cultivars (CSH 22 SS, NTJ2 and ICSV 93046) with two row spacings (60 and 45 cm) and six nitrogen levels (0, 30, 60, 90, 120, and150 kg ha−1) were grown on Vertisols during three post rainy (November to April) seasons at the ICRISATcenter farm in Patancheru, India. The results showed that the row spacings (60 or 45 cm) had no influenceon performance of the cultivars. Sweet sorghum hybrid CSH 22 SS produced the highest green stalk yield(45.4 Mg ha−1) and grain yield (2.33 Mg ha−1) compared to NTJ 2 (32.66 Mg ha−1and 1.70 Mg ha−1) andICSV 93046 (38.44 Mg ha−1and 2.03 Mg ha−1). Net economic return from CSH 22 SS (US$ 681 ha−1) wasalso significantly higher than that from NTJ 2 (US$ 415 ha−1) and ICSV 93046 (US$ 539 ha−1). All cultivarsresponded to applied N up to 150 kg ha−1; however beyond 90 kg ha−1N rate, the increase in yield wasinsignificant. Estimated N use efficiency (NUE) values indicated that 90 kg N ha−1was an optimum Nlevel for sweet sorghum crop. Simulated soil water balance components revealed that reduction in totaltranspiration due to water stress was 20 to 45% compared to the no-stress. In case of water use efficiency,CSH 22 SS showed the highest economic returns per unit volume of water input. Based on these results, itis concluded that sweet sorghum hybrid CSH 22 SS at 90 kg N ha−1is the best remunerative combinationfor maximizing yield, economic returns and resource use efficiency