Comparisons of regeneration rate and yields performance between inbred and hybrid rice cultivars in a direct seeding rice-ratoon rice system in central China

Ratoon rice system is one method to increase food production in areas where the annual accumulation of temperature and light resources are considerably more than that required for single-cropping rice but not enough for double-season rice. Direct seeding rice-ratoon rice (DSR-RR) is an alternative rice planting system to traditional transplanted rice-ratoon rice (TTR-RR) in central China, requiring less labor. Hybrid rice has higher yield potential than inbred rice under TTR-RR. However, little attention has been paid to the differences in growth and yield performance of inbred and hybrid rice cultivars in DSR-RR. Field experiments were conducted to evaluate the performance of widely grown inbred and hybrid rice cultivars in central China in 2016 and 2017. Significantly higher ratoon season yields were observed in hybrid rice cultivars than inbred rice cultivars. The ratoon season yield that was achieved was 4.19 t ha(-1) in inbred rice cultivar and 5.71 t ha(-1) in hybrid rice cultivar in 2016. Similarly, the ratoon season yields ranged from 2.39 to 3.99 t ha(-1) in inbred rice cultivars and from 3.84 to 4.90 t ha(-1) for hybrid rice cultivars in 2017. Significantly higher regeneration rates contributed to the higher ratoon season yield in hybrid rice cultivars than inbred ones. Further research indicated that higher regeneration rate was associated with higher dry weight per stem after harvesting of the first crop in hybrid rice cultivars as compared with inbred ones. Furthermore, higher annual grain yields were observed in hybrid than in inbred rice cultivars in both years, indicating that hybrid rice cultivars may be more suitable for DSR-RR. To achieve high ratoon season and annual yields in DSR-RR in central China, cultivars should be selected with comprehensive considerations of high regeneration rates and lodging resistance.