Growth and development characteristics of super-high-yielding mid-season japonica rice

Abstract

Rice is one of the most important food crops in China. The realization of the super-high-yielding (SHY) type has great significance in ensuring food security in this country. This study investigated the growth and development characteristics of the super-high-yielding rice (grain yield> 11 t/hm²). Four mid-season japonica rice cultivars (including lines): Lianjiajing 2, Huajing 5, 0026 and 9823, were grown in the paddy field. Growth analysis was performed during the growth period, and yield components were determined at maturity. Results showed that SHY rice had more sipkelets per panicle and higher filled-grain percentage than the high-yielding rice (CK, grain yield 8.98 9.16 t/hm²). There was no significant difference in the 1 000-grain weight between the super-high-yielding and the CK. Super-high-yield rice exhibited fewer tillers at the early growth stage (from transplanting to jointing), with a higher ratio of productive tillers to total tillers, when compared with the CK. The leaf area index (LAI), photosynthetic potential and dry matter accumulation were lower for the SHY rice than those for the CK at the early growth stage, and the differences were not significant between the two rice types at heading, but were greater in the former than the latter after heading. The root-shoot ratio at each growth stage, root bleedings from heading to maturity, grain-leaf ratio, translocation percentage of the matter from stems and sheaths and harvest index of super-high-yielding rice were greater than those of CK. The indexes for the growth and development of SHY mid-season rice population were suggested, i.e. total spikelets >4.5?10⁴/m², filled-grain percentage>90%, 1 000-grain weight>26 g; ratio of productive tillers>80%, leaf area index at heading 7.5 8.0, photosynthetic potential during the whole growth period >5?10⁶ m² " d/hm², total dry matter weight at maturity >22 t/hm², harvest index >0.51; grain-leaf ratio (number of spikelets per cm² leaf area) >0.58; root-shoot ratio at heading >0.25 and amount of root exudates >5 g/m² " h. The regulation approaches and key cultivation techniques for raising the super-high-yielding population were also discussed.

Keywords

mid-season japonica rice, super-high-yielding, growth and development, regulation approach