Abstract
Early-maturing japonica/indica hybrids (EJIH) have recently been released, performing a yield potential of 13.5 t ha−1 and greater yield increase over conventional japonica rice (CJ) and hybrid indica rice (HI) in production. More spikelets per panicle and improved grain-filling efficiency underlined the basis for the superior yield performance of EJIH. However, few studies are available on the panicle traits and grain-filling characteristics of EJIH, as well as their differences to CJ and HI. In our study, two EJIH, two CJ, and two HI cultivars with similar growth patterns were grown in the same fields. EJIH had a 12.2–18.8% increased (p < 0.05) grain yield relative to CJ and HI, mainly attributed to their higher daily grain yield. Although it had a lower panicle per m2, EJIH exhibited 28.0–38.3% more (p < 0.05) spikelets per m2 from an increase of 58.0–87.8% (p < 0.05) in spikelets per panicle than CJ and HI. Compared with CJ and HI, EJIH had a higher single panicle weight and more grains in the six parts of the panicle, especially in the upper secondary branches (US) and middle secondary branches (MS). EJIH exhibited a higher leaf area index (LAI), leaf area duration (LAD), leaf photosynthetic rate, and SPAD values after heading, which helped increase shoot biomass weight at heading and maturity and post-heading biomass accumulation. For CJ and HI, the grain-filling dynamics of grains in the six parts were all well simulated by the Richards equation. For EJIH, the grain-filling dynamics of grains in the lower secondary branches (LS) were well fitted by the logistics equation, with the Richards equation simulating grain positioning on the other five parts. EJIH had a lower mean grain-filling rate (GRmean) and longer days and grain filling amounts (GFA) during early, middle, and late stages than CJ and HI. Our results suggest EJIH gave a yield advantage over CJ and HI through a higher daily grain yield. The panicle traits and grain-filling characteristics differed greatly among the three cultivar types. Compared with CJ and HI, EJIH had lower GRmean and higher days and more grains in the panicle during early, middle, and late stages, which contributed to an increased GFA after heading, improved filled-grain efficiency, and higher grain yield.
Highlights
The dominated cropping system in the lower reaches of the Yangtze River, China, is a rotation of rice and wheat [1]
Considerable strides have been achieved in solving such constraints and japonica/indica hybrids with an early maturity and high yield potential have become available in production, such as Yongyou 2640 in our study
A similar growth pattern among the three cultivar types indicated a comparable amount of intercepted solar radiation during the growth period; Early-maturing japonica/indica hybrids (EJIH) had a better solar radiation use efficiency benefitting from the improved plant posture and capability of capturing light resources [28]
Summary
The dominated cropping system in the lower reaches of the Yangtze River, China, is a rotation of rice and wheat [1]. In this system, rice is sown after harvesting wheat, and wheat is sown after harvesting rice. Late-maturing rice cultivars with high yield performance have been widely planted by farmers. These late-maturing rice cultivars are always harvested late, which delays the sowing date of wheat and cause a yield penalty [5,6]. Rice cultivars with an early maturity and high yield potential are greatly needed to achieve the dual goals of high yields of rice and wheat in a rice-wheat cropping system
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
