Slimming the Grain through Breeding Is a Practical Way to Reduce the Chalky Grain Rate of Middle-Season Hybrid Rice

Abstract

The production of middle-season rice is an important part of agriculture in the Yangtze River basin of China. In recent years, the chalky grain rate of middle-season rice has decreased with the release of new cultivars. However, limited information is available on the factors responsible for this change in the chalky grain rate. This study evaluated the trends in the chalky grain rate and grain size traits of the new cultivars and the relationships between the chalky grain rate and grain size traits for middle-season hybrid rice in a province located in the middle reaches of the Yangtze River basin during 2006–2021. The results indicate that the recently reduced chalky grain rate of middle-season hybrid rice in the new cultivars is closely associated with a decrease in rice width, suggesting that it is feasible to reduce the chalky grain rate of middle-season hybrid rice by slimming the grain through breeding.

Grain Yield and Yield Attributes of Currently Popular Hybrid Rice Varieties Compared to Representative Super Hybrid Rice Varieties in Subtropical Environments

“…In general, appearance quality increases with decreasing grain weight [19]. Most recently, Huang et al [20] reported that grain weight and chalky grain rate decreased synchronously with the year of varietal release in middle-season hybrid rice cultivars released in Hunan Province of China from 2006 to 2021. Although this study did not determine grain quality, regional variety testing showed that the quality of the popular hybrids used in this study reached the second or third grade of high-quality rice standards in China (https://www.ricedata.cn/variety, accessed on 18 December 2023).…”

The Improvement in Head Milled Rice Yield in Middle-Season Hybrid Rice: Evidence from a Case Study of Two Cultivars Released 18 Years Apart

“…Rice grain chalkiness is a polygenic quantitative trait. Although many quantitative trait loci (QTLs) related to rice grain chalkiness have been detected [17], these QTLs cannot be directly used to explain the change in rice grain chalkiness with the development of new cultivars because they have not been practically applied in recent rice breeding programs [12]. From another point of view, rice grain chalkiness is related to some other rice grain traits, and hence the change in rice grain chalkiness can be explained by the changes in related rice grain traits [11,12,18].…”

“…Although many quantitative trait loci (QTLs) related to rice grain chalkiness have been detected [17], these QTLs cannot be directly used to explain the change in rice grain chalkiness with the development of new cultivars because they have not been practically applied in recent rice breeding programs [12]. From another point of view, rice grain chalkiness is related to some other rice grain traits, and hence the change in rice grain chalkiness can be explained by the changes in related rice grain traits [11,12,18]. Huang et al [12] reported that the decrease in the occurrence of chalkiness in middle-season hybrid rice with the development of new cultivars in recent years (2006-2021) was related to a decrease in rice grain size.…”

“…From another point of view, rice grain chalkiness is related to some other rice grain traits, and hence the change in rice grain chalkiness can be explained by the changes in related rice grain traits [11,12,18]. Huang et al [12] reported that the decrease in the occurrence of chalkiness in middle-season hybrid rice with the development of new cultivars in recent years (2006-2021) was related to a decrease in rice grain size. This was also partially responsible for the lower CD in JLY1468 than in LYPJ in this study.…”

“…HMRR is closely related to the shape and chalkiness traits of rice grains, and a high HMRR can be achieved from a high rice grain width (RGW) and/or a low occurrence of chalkiness [9,11]. Our recent study showed that both RGW and chalky grain rate (CGR) in middle-season hybrid rice have been significantly decreased with the year of cultivar release [12]. Based on such a finding, it is difficult to speculate whether HMRR and head milled rice yield in middle-season hybrid rice are improved due to the development of new cultivars.…”