Abstract
The yield potential of rice (Oryza sativa L.) has experienced two significant growth periods that coincide with the introduction of semi-dwarfism and the utilization of heterosis. In present study, we determined the annual increase in the grain yield of rice varieties grown from 1936 to 2005 in Middle Reaches of Yangtze River and examined the contributions of RUE (radiation-use efficiency, the conversion efficiency of pre-anthesis intercepted global radiation to biomass) and NUE (nitrogen-use efficiency, the ratio of grain yield to aboveground N accumulation) to these improvements. An examination of the 70-year period showed that the annual gains of 61.9 and 75.3 kg ha−1 in 2013 and 2014, respectively, corresponded to an annual increase of 1.18 and 1.16% in grain yields, respectively. The improvements in grain yield resulted from increases in the harvest index and biomass, and the sink size (spikelets per panicle) was significantly enlarged because of breeding for larger panicles. Improvements were observed in RUE and NUE through advancements in breeding. Moreover, both RUE and NUE were significantly correlated with the grain yield. Thus, our study suggests that genetic improvements in rice grain yield are associated with increased RUE and NUE.
Highlights
Rice is the most important staple food crop in Asia and has significantly contributed to global food security in the past, and will continue to feed approximately half of the global population in the future[3,7]
Annual grain yield gains of 75 to 81 kg ha−1 have been obtained for irrigated rice at International Rice Research Institute (IRRI) since 1966, gains of 42 kg ha−1 have been obtained for irrigated rice in Texas since 1944, and gains of 15.7 kg ha−1 have been obtained for upland rice in Brazil since 198416,18,19
We determined the genetic improvements in the grain yield for rice varieties grown from 1936 to 2005 in Middle Reaches of Yangtze River, and found that significant increases in Radiation-use efficiency (RUE) and NUE contributed to the increased grain yields in the advance of rice breeding in Middle Reaches of Yangtze River
Summary
Rice is the most important staple food crop in Asia and has significantly contributed to global food security in the past, and will continue to feed approximately half of the global population in the future[3,7]. Radiation-use efficiency (RUE) is defined as the efficiency of using intercepted radiation to produce biomass by crops, and it is regarded as the only remaining major prospect for improving yield potential[24]. Genetic improvements in N uptake (NUP) and N use efficiency for grain production (NUEg) have been found in wheat[32], maize[33], and cotton[34]. The grain yield, yield components, plant morphology, radiation interception, RUE, NUP and NUEg were determined in a two-year field experiment using widely disseminated varieties in various decades since the 1930s in China. We determined the genetic improvements in the grain yield for rice varieties grown from 1936 to 2005 in Middle Reaches of Yangtze River, and found that significant increases in RUE and NUE contributed to the increased grain yields in the advance of rice breeding in Middle Reaches of Yangtze River
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