Hydraulic conductance as well as nitrogen accumulation plays a role in the higher rate of leaf photosynthesis of the most productive variety of rice in Japan

• Published in: Journal of experimental botany Vol. 62; no. 11; pp. 4067 - 4077
• Main Authors: Taylaran, Renante D., Adachi, Shunsuke, Ookawa, Taiichiro, Usuda, Hideaki, Hirasawa, Tadashi
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01-07-2011
• Subjects: Biological and medical sciences; Biomass; Dry matter accumulation; Fundamental and applied biological sciences. Psychology; Hydraulics; Japan; Leaves; Nitrogen; Nitrogen - metabolism; Oryza - growth & development; Oryza - metabolism; Panicles; Photosynthesis; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Leaves - physiology; Plant physiology and development; Plant Roots - growth & development; Plant Roots - metabolism; Plant Roots - physiology; Plants; RESEARCH PAPER; Research Papers; Rice; Species Specificity; Stomatal conductance; Tillering; Asia; Japan; Far east; hydraulic conductance; stomatal conductance; hydraulic conductivity; photosynthesis; root surface area; Dry matter production; ); rice; ribulose-1; high-yielding variety; leaf nitrogen; 5-bisphosphate carboxylase/oxygenase (Rubisco); Monocotyledones; Dry matter; Ribulose-bisphosphate carboxylase; Lyases; Hydraulic conductivity; High yielding variety; Cereal crop; Oryza sativa; rice (Oryza sativa); Gramineae; Carboxy-lyases; Angiospermae; Botany; Conductance (fluid); Carboxylase; Root; Enzyme; Stomatal conductance; Plant leaf; Nitrogen; Oxygenase; Carbon-carbon lyases; Spermatophyta; Oxidoreductases; Surface area; Photosynthesis
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/err126

An indica variety Takanari is known as one of the most productive rice varieties in Japan and consistently produces 20–30% heavier dry matter during ripening than Japanese commercial varieties in the field. The higher rate of photosynthesis of individual leaves during ripening has been recognized in Takanari. By using pot-grown plants under conditions of minimal mutual shading, it was confirmed that the higher rate of leaf photosynthesis is responsible for the higher dry matter production after heading in Takanari as compared with a japonica variety, Koshihikari. The rate of leaf photosynthesis and shoot dry weight became larger in Takanari after the panicle formation and heading stages, respectively, than in Koshihikari. Roots grew rapidly in the panicle formation stage until heading in Takanari compared with Koshihikari. The higher rate of leaf photosynthesis in Takanari resulted not only from the higher content of leaf nitrogen, which was caused by its elevated capacity for nitrogen accumulation, but also from higher stomatal conductance. When measured under light-saturated conditions, stomatal conductance was already decreased due to the reduction in leaf water potential in Koshihikari even under conditions of a relatively small difference in leaf–air vapour pressure difference. In contrast, the higher stomatal conductance was supported by the maintenance of higher leaf water potential through the higher hydraulic conductance in Takanari with the larger area of root surface. However, no increase in root hydraulic conductivity was expected in Takanari. The larger root surface area of Takanari might be a target trait in future rice breeding for increasing dry matter production.