Sweet sorghum performance under irrigated conditions in northwest China : Biomass and its partitioning in inbred and hybrid cultivars at two nitrogen levels

Effects of cultivar choice and nitrogen supply on biomass yield and dry matter partitioning of sweet sorghum [Sorghum bicolor (L.) Moench] were studied under irrigated conditions in the arid temperate climate of north-west China. Two hybrid cultivars, Zaoshu-1 (ZS 1) and Chuntian-2 (CT 2), and two inbred cultivars, Rio and Lvneng-3 (LN 3) were grown in a field trial at two nitrogen fertilizer levels (0 and 150 kg/ha of N) in Urumchi (43°01'N, 88°37'E). Hybrid cultivars produced much higher aboveground dry biomass yields, amounting to on an average 27.2 t/ha than inbred cultivars with on an average 24.3 t/ha. Crop growth rates amounted to 30.8 g/m2/day on an average during the period from elongation to heading as well as from heading to maturity, however; the growth rates of the inbred cultivars slowed down after heading, while those of the hybrids still increased. Inbred cultivar Rio had the highest plant height (328 cm) and stem dry weight (16.5 t/ha). Average grain yield was 11.2 and 5.5 t/ha for hybrids and inbreds, respectively. Partitioning of dry matter differed between the inbred cultivars, but did not for the hybrids. Application of fertilizer nitrogen resulted in a higher plant height, stem dry biomass, dry biomass of leaves and aboveground biomass in inbred and hybrid cultivars. In conclusion, hybrid and inbred cultivars of sweet sorghum performed well in the environment of north-west China when irrigated. Biomass and grain yields of hybrids turned out to be higher than those of inbreds.