Convenient estimation of unfertilized grains in rice

Tohru Kobata, Yoshio Akiyama, Takuya Kawaoka

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


Failure of fertilization in rice is a critical yield-determining factor in plants subjected to temperature or water stress at the early-reproductive stage and in high-yield cultivars bearing heavy spikelets. Although it is important to identify quickly the unfertilized spikelets for research and selection of stress-resistant or high-ripening cultivars from bulk samples, the identifi cation takes time because unfertilized spikelets are usually determined by visual and manual procedures. Our objective was to develop a convenient method to identify unfertilized spikelets in rice. Takanari spikelets at maturity grown in the paddy fi eld were separated into floating and sinking spikelets by different specific gravity solutions of ethanol/water mixture. The unfertilized spikelets were identified by checking the grains inside the spikelets by light penetration and examining the spikelets manually. The percentage of floating spikelets decreased with the increase in ethanol concentration, and that of floating spikelets approximately coincided with the percentage of unfertilized spikelets when the specifi c gravity was below 0.90×103 kg m-3, corresponding to over 70%-ethanol. In a practical range of temperature the specific gravity scarcely changed. In an 80%-ethanol solution, the percentages of floating spikelets in Takanari grown under different nitrogen applications and in rice cultivars having different spikelet size approximately coincided with percentages of unfertilized spikelets, though the percentages of floating spikelets was 5 to 7% higher than the unfertilized spikelets. The use of 70%-ethanol solution increased the difference in some rice cultivars. We concluded that the gravitation method would be convenient for identifi cation of unfertilized spikelets in bulk samples of rice.

Original languageEnglish
Pages (from-to)289-296
Number of pages8
JournalPlant Production Science
Issue number3
Publication statusPublished - 2010
Externally publishedYes


  • Cultivar
  • Gravitational method
  • Rice
  • Ripened grain
  • Sterility
  • Stress
  • Unfertilized spikelet

ASJC Scopus subject areas

  • Agronomy and Crop Science


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