Rice grain yield hinges on four components: panicle number, spikelets per panicle, filled-grain rate, and grain weight. Among these, spikelets per panicle offers the greatest untapped potential. However, simply increasing spikelet number requires a proportional increase in vegetative biomass, which limits yield gains. A more efficient route, therefore, is to produce more spikelets per unit of biomass–a concept the researchers term spikelet production efficiency (SPE).
“SPE is defined as the number of differentiated spikelets per panicle divided by the dry weight of vegetative organs (culm, leaves, and sheaths) per shoot at the spikelet differentiation stage,” explains Prof. Jianchang Yang, corresponding author of a new study in the field. “It measures how efficiently a rice plant converts vegetative growth into reproductive sink capacity.”
SPE provides a physiological criterion to evaluate how efficiently a rice plant converts vegetative biomass into reproductive sink capacity. “Our analyses show that SPE is linearly and positively correlated with grain yield and harvest index, with correlation coefficients even higher than those for vegetative organ dry weight alone,” adds Yang.
By comparing multiple rice varieties grown under high-yielding populations, the team found that higher SPE varieties produced more spikelets per panicle and achieved greater grain yield and harvest index. “Higher SPE did not reduce filled-grain rate or 1,000-grain weight,” says Dr. Weiyang Zhang, first author and co‑corresponding author of the study. “Moreover, it was associated with improved post-anthesis leaf photosynthesis, shoot dry matter accumulation, and non-structural carbohydrate (NSC) remobilization from stems.”
These findings suggest that a larger sink capacity actively “pulls” photoassimilates from source organs, enhancing the rice plant’s overall carbon economy.
“Improving SPE could serve as a new key criterion for breeding super-high-yield rice varieties and developing cultivation strategies,” adds Zhang. “We are now investigating the genetic and molecular mechanisms underlying SPE to provide novel insights for rice improvement.”
The team published their findings in the Journal of Integrative Agriculture .
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Contact Authors:
Weiyang Zhang, E-mail: wyz@yzu.edu.cn;
Jianchang Yang, E-mail: jcyang@yzu.edu.cn
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Journal of Integrative Agriculture
Experimental study
Not applicable
Improving spikelet production efficiency is crucial for further unleashing yield potential in rice
The authors declare that they have no conflict of interest.