Objective It aims to study the yield performance and source-sink-flow characteristics of new strain of super-large-panicle rice DS23 in early season, and explore the source-flow-sink characteristics and super-high yield potential of DS23, with an aim to provide theoretical basis for high-yield breeding and cultivation of early rice in South China.

Method The study was conducted under field conditions with the new super-large panicle type strain DS23 as test material and the medium to large panicle type variety YHSM as the control. The leaf area index, SPAD value, accumulation and transport characteristics of non-structural carbohydrate (NSC) in stems, anatomical characteristics of vascular bundles and yield component factors of different panicle types of rice were measured and compared.

Result The number of grain per panicle, grain weight, sink capacity and yield of DS23 were increased by 37.3%, 4.0%, 33.7% and 15.9% respectively compared to those of YHSM seedlings. The effective number of panicles and seed setting rate were significantly decreased by 6.8% and 15.1% compared to those of YHSM seedlings. There was no significant difference in leaf area index and flag leaf SPAD value between the two varieties at heading stage. Compared with YHSM, total mass of NSC reserved in stem and apparent contribution of transferred NSC to grain yield of DS23 were significantly reduced by 15.3% and 19.8%, respectively, and the apparent transport rate of stem sheath NSC was significantly increased by 10.3%; The DS23 vascular bundle number was significantly increased by 17.3%, and there was no significant difference in the vascular bundle area between the two varieties; DS23 showed no significant change in grain/leaf ratio, with a significant decrease in NSC/spikelet ratio of 34.2% and an increase in vascular bundle load index of 20.4%-60.2%.

Conclusion The super-large panicle type rice germplasm DS23 planted in early season has a large sink capacity, well-developed vascular bundles transport organization, strong material transformation ability in later stage and great potential for high yield and yield increase. Improvement in seed setting rate is a main direction for exploring its super-high yield potential. The study result lays a theoretical foundation for the breeding of super-large panicle early rice varieties and the research and development of high yield cultivation techniques.