Abstract
Rice yield potential was greatly improved since the green revolution, but the occurrence of lodging often restricts the achievement of potential yield. Currently, it is still obscure about how the lodging-related traits change along with the genetic improvement in yield potential of rice, although much efforts have been devoted to study the trend of and physiological mechanisms underlying changes in grain yield. Therefore, fourteen rice mega-varieties that were released and disseminated from 1930s to 2005 in China were investigated through a two-year experiment in the field condition. The results showed that large genotypic differences in lodging-related morphological traits were observed among these varieties. Lodging index (LI) of semi-dwarf varieties was significantly lower compared with that of SLX(Shenglixian). There were significant differences in LI among the semi-dwarf varieties, but no relationship between LI and the release year was found. Bending moment (BM) of semi-dwarf varieties released in 1940s-1980s was significantly lower than that of SLX. However, varieties released after 1980s had similar bending moment with SLX, but significantly higher breaking resistance (BR). The increase in both BM and BR after 1980s was related with the increase in internode diameter (ND) and stem fresh weight. Overall, this study disclosed the changing pattern of lodging-related traits in the genetic improvement of rice, and suggested that further increase in ND, internode dry weight (NDW) and dry weight per unit length (DWUL) of lower internode in modern super rice variety could effectively enhance lodging resistance and bring down LI.
Highlights
Rice (Oryza sativa L.) is a major staple food for more than half of world's population [1]
The success of super-hybrid rice was due to a combination of superior agronomic characteristics of IRRI’s New Plant Type and intersubspecific heterosis [4], which led to a 12% advantage in yield potential compared with
Similar trend was observed for the N3 internode length (NL) in the process of genetic improvement (Fig 2C and 2D), except that NL of the varieties released after 1980s had similar values with SLX (Table 2)
Summary
Rice (Oryza sativa L.) is a major staple food for more than half of world's population [1]. Yield potential of rice was greatly improved since the green revolution due to the development of semi-dwarf varieties in the late 1950s, three-line hybrids in the late 1970s, and super-hybrid rice since 1996 [2,3]. The success of super-hybrid rice was due to a combination of superior agronomic characteristics of IRRI’s New Plant Type and intersubspecific heterosis [4], which led to a 12% advantage in yield potential compared with. Genetic Improvement in Lodging-Related Traits ordinary hybrids and inbred varieties [5]. The higher grain yields of super-hybrid rice are attributed to improvement in both source and sink capacity [6], and improvement in crop management [4]
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