Morphological, anatomical, and physiological characteristics involved in development of the large culm trait in rice

Abstract

The large culm trait is an important agronomical characteristic in crops. Although the effects of this trait on lodging resistance, yield production, and biomass accumulation have been widely examined, its significance in super rice breeding remains to be determined. In our current study, the morphological, anatomical, and physiological characteristics of three large culm rice ( Oryza sativa L.) cultivars (JH186, JH126, and JH214) were compared to three common rice cultivars (Xiushui09, Xiushui63, and Zhenuo5). Overall, the large culm cultivars exhibited greater plant size, culm diameter, and flag leaf length and width, as well as lower tiller numbers, although variations were observed among the six rice cultivars. The large culm cultivars also exhibited larger leaf vascular bundles, more culm vascular bundles, more grains per panicle and blighted grains, lower seed-setting rates, and larger panicles. The transpiration rate was significantly higher in the large culm cultivars, whereas instantaneous water use efficiency was lower compared to the common cultivars. JH186 and JH214 also exhibited higher photosynthetic efficiency and apoplastic transport ability. These results indicate that a systematic modification of morphology, anatomy, and physiology was involved in the development of the large culm trait in rice, and cultivars with large culm characteristics are ideal candidates for super rice breeding.