Estimation of sink capacity of rice grains: A comparison of calculation methods based on 1000-grain weight and grain projected area

• Published in: Plant production science 2023-07, Vol.ahead-of-print (ahead-of-print), p.1-13
• Main Authors: Okamura, Masaki, Morita, Ryutaro, Arai-Sanoh, Yumiko, Yoshida, Hiroe, Nakagawa, Hiroshi, Aoki, Naohiro
• Format: Article
• Language: English
• Subjects: brown rice thickness; Cultivars; Density; grain area; Grain size; Oryza sativa; Particle size; Rice; Specific gravity; Thickness; thousand grain weight; Weight
• ISSN: 1343-943X; 1349-1008
• DOI: 10.1080/1343943X.2023.2228500

Accurate estimation of sink capacity in rice (grain number × potential grain size), independent of grain filling, is necessary for considering source - sink interactions. However, how to measure potential grain size is still a matter of debate. Here, we investigated the effect of modifying the grain-filling environment on 1000-grain weight of grains screened by specific gravity or brown rice thickness, grain projected area ('grain area'), or husk weight as candidate indicators of potential grain size using a japonica cultivar Koshihikari and its near-isogenic line with greater spikelet number. We found grain area to be the best, followed by 1000-grain weight. We developed a novel method to calculate sink capacity from grain area; the method was developed based on the relationship between individual grain weight and grain area. Comparison with the conventional method based on 1000-grain weight showed that although the method based on grain area is more accurate, that based on 1000-grain weight is useful enough, because screening by specific gravity or brown rice thickness selected filled grains well, and the effect of the grain-filling environment on 1000-grain weight was limited.