Abstract
To reveal the physiological mechanism underlying the yield advantage of super hybrid rice compared with inbred super rice, a super hybrid rice cultivar Yliangyou 3218 (YLY) and an inbred super rice cultivar Zhendao 11 (ZD) were field grown under five nitrogen (N) fertilizer rates in 2016 and 2017. The average grain yield of YLY across nitrogen fertilizer rates was 10.1 t ha−1 in 2016 and 9.7 t ha−1 in 2017, 29.6% and 21.3% higher than that of ZD in 2016 and 2017, respectively. YLY showed higher above-ground biomass accumulation, especially growth before heading, which was mainly due to its faster green leaf area index (GLAI) formation and greater maximum GLAI (GLAImax). The daily radiation interception (RIdaily) was 15.0% higher in YLY than ZD, but the accumulated radiation interception (RIacc) before heading showed little difference between them because ZD had a longer growth duration. The radiation use efficiency (RUE) of YLY before heading was 54.7% higher than that of ZD (YLY, 2.12 g MJ−1; ZD, 1.37 g MJ−1). Our result demonstrated that the yield advantage of YLY was due to its higher above-ground biomass before heading, which was mainly achieved by its improvement in RUE rather than radiation interception.
Highlights
Rice is the main staple food in the world
In terms of yield components, it was found that the yield superiority of Yliangyou 3218 (YLY) compared with Zhendao 11 (ZD) mainly resulted from the spikelet per panicle, which was consistent with previous studies [26,27]
The results found that daily radiation interception (RIdaily) and radiation use efficiency (RUE) of YLY was both enhanced compared with that of ZD (Figure 5 and Figure S3)
Summary
Rice is the main staple food in the world. To meet the substantial increases in food demand due to the rapidly increasing population, rice yield needs to improve further. One of the largest rice producers, has successfully increased rice yield through genetic improvement and improved crop management practices [1,2,3]. Compared with a 3.7% yearly yield increase in 1980s, the increment dropped to 0.9% in 1990s [4]. In order to break the yield ceiling, a “super rice” mega-project was established in 1996 in China [5]. 131 “super” rice varieties have been released. A yield more than 12 t ha−1 was found in the field experiments which adopted these varieties [6]
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