Combining ability of cytoplasmic male sterility on yield and agronomic traits of sorghum for grain and biomass dual-purpose use

Abstract

Sorghum [Sorghum bicolor (L.) Moench] is a high-yielding C4 crop used not only to produce grains for food, feed, and industrial uses but also biomass (i.e., leaf and stem) for biofuel production. To take better advantage of its heterosis for both grain and biomass dual-purpose use, the combining ability of 34 cytoplasmic male sterile lines (female) were tested with 3 cytoplasmic male fertile restore lines (male) using the North Carolina design (NCⅡ) at Zhuozhou (Hebei province) and Jiexiu (Shanxi province) in northern China for two years (2017 and 2018). The hybrids exhibited a grain yield of 0.3 ∼ 14.0 t ha−1 and had an aboveground biomass yield (AGBY) of 9.6 ∼ 109.9 t ha−1 across both sites in 2017 and 2018. The genotype and site × genotype interactions significantly affected the yield and agronomic traits. With respect to their grain and biomass dual-purpose use, the tested 34 female lines revealed that plant height, gravity center height, productive tiller rate, and harvest index were strongly general combining ability (GCA) sensitive. Stem width, days to maturity, AGBY, and grain width were medium GCA-sensitive; and grain yield, 100-grain weight, days between heading and maturity, and grain bulk density were weakly GCA-sensitive. The GCA effect on grain yield was positive and significantly correlated with productive tiller rate, AGBY, and harvest index. The GCA effect on AGBY had a positive, significant correlation with plant height, gravity center height, productive tiller rate, and days to maturity; but the effect was negatively correlated with 100-grain weight and grain width. For tested traits, the additive gene effects strongly predominated over the non-additive genes for tested traits. Plant height was the most GCA-sensitive trait and the most important for biomass production. Female lines AMP418, AMP431, AMP434, AMP443, AMP495, AMP496 and the male line X097 were selected as being high-GCA effect germplasm. These selections from newly introduced cytoplasmic male sterile lines hold promise for accelerating the genetic improvement of sorghum for its dual-purpose use as grain for food and biomass for biofuel.