Grain yield improvement in high-quality rice varieties released in southern China from 2007 to 2017

Abstract

In recent years, high-quality rice varieties have been widely cultivated for food production in southern China. However, changes in the yield performance of different high-quality rice varieties are still unclear. In this study, the yield and yield components of 710 different types (hybrid or inbred rice and japonica or indica) of high-quality rice varieties were investigated in six provinces from 2007 to 2017. The results showed that, from 2007 to 2017, the grain yield and yield traits, including the number of spikelets per panicle and seed-set percentage, of high-quality indica rice varieties increased significantly, while the number of panicles decreased only in indica inbred rice. The grain yield of high-quality japonica rice also increased significantly, whereas japonica hybrid rice increased the number of spikelets per panicle and decreased the number of panicles. Compared with inbred rice, hybrid rice had a significant increase in grain yield due to a higher number of spikelets, rather than a lower number of panicles and seed-set percentage. Meanwhile, japonica rice showed higher grain yield than indica rice, which was attributed to seed-set percentage and an optimized structure between the number of panicles and the number of spikelets. In addition, the coefficient of variation of the grain yield of japonica rice decreased, whereas that of indica rice increased over time, and those of the number of panicles and seed-set percentage remained stable. Among the six provinces, Zhejiang had the highest grain yield because the number of spikelets per panicle and seed-set percentage increased over time. Our results suggested that, based on an increase in the yield potential of high-quality rice varieties over the past 11 years, future breeding of high-quality rice should be emphasized to improve the number of panicles and seed-set percentage for hybrid rice and the number of spikelets for inbred rice, especially the grain weight for indica inbred rice.

Changes in the Grain Yield and Quality of Early Indica Rice from 2000 to 2020 in Southern China

“…Therefore, attention should be paid to improving the spikelet number per panicle in early indica rice breeding. Meanwhile, we did not observe any correlation between grain yield and 1000-grain weight, which was consistent with previous findings that grain yield was independent of grain weight in indica rice [15,22]. These results suggest that, during indica rice breeding, the contribution of grain weight to yield improvement may be negligible.…”

“…Wang et al [22] analyzed the relationships between yield components and grain quality traits among different high-quality rice varieties, and they found that grain yield was positively correlated with the chalky rice rate, which was consistent with the results of this study (Figure 2). However, Wang et al [22], did not investigate relationships among grain quality traits, which are expected to hinder the collaborative improvement of grain quality traits. The results of this study indicate that a network of grain quality traits should be established to achieve the simultaneous improvement of multiple traits.…”

“…This could be explained, at least partly, by the results of this study, which showed that grain yield per area significantly increased in early indica rice from 2000 to 2020. In line with this study, Wang et al [22] found significant increases in the grain yield of high-quality indica rice varieties released from 2000 to 2017 in southern China. The authors suggested that an increased spikelet number per panicle and seed-set rate contributed to the observed improvement in the yield of indica hybrid rice [22], which was in line with our results showing that an increased spikelet number per panicle was also observed over the studied years in early indica rice (Table 1).…”

“…In line with this study, Wang et al [22] found significant increases in the grain yield of high-quality indica rice varieties released from 2000 to 2017 in southern China. The authors suggested that an increased spikelet number per panicle and seed-set rate contributed to the observed improvement in the yield of indica hybrid rice [22], which was in line with our results showing that an increased spikelet number per panicle was also observed over the studied years in early indica rice (Table 1). Most early indica rice is not part of the high-quality rice population, but our main data source was indica hybrid rice (Table S1).…”

“…Although some studies have investigated changes in grain yield and quality in rice varieties released in different years [11,13,14,22,23], no previous study has systematically investigated the relationships among yield components and grain quality traits, especially in early indica rice, which may hinder the improvement of both grain yield and quality from the perspective of variety selection. Therefore, the objectives of this study were to (1) compare changes in yield and quality traits in 224 early indica rice varieties from 2000 to 2020 and (2) explore the possibility of synergistically improving grain yield and quality in early indica rice.…”