Yield performance of direct-seeded, double-season rice using varieties with short growth durations in central China

The labor shortage requires that double-season rice be planted with direct-seeded crop establishment. Only the varieties with short growth durations can be used in direct-seeded, double-season rice under subtropical conditions in central China in which the thermal time is limited. The objective of this study was to evaluate the grain yield and associated plant traits of direct-seeded, double-season rice using varieties with short growth durations. Field experiments were conducted using five short-duration varieties in the early and late seasons of 2015 and 2016 in Wuxue County, Hubei Province, central China. The grain yield ranged from 6.40 to 9.88 t ha(-1) with a total growth duration of 89 to 105 d across varieties, seasons, and years. The wide difference in grain yield was attributed to the spikelets per panicle and biomass production. Overall, Zaoxian615 (ZX615) produced relatively high grain yield across seasons and years among the five varieties due to its tall plants, heavy panicles, and high crop growth rate. The high temperatures during the vegetative stage and low daily minimum temperatures during the ripening period were critical for the yield performance of the early-season rice, whereas the grain yield of the late-season rice was largely driven by the high daily solar radiation during the reproductive and ripening periods. Our results suggested that rice breeders should develop short-duration rice varieties with a high crop growth rate and biomass production through desirable plant traits of tall plants and heavy panicles to further improve the grain yield of direct-seeded, double-season rice in central China.