Relationship between Leaf Photosynthesis and Nitrogen Content of Field-Grown Rice in Tropics
Peng, Shaobing | Cassman, Kenneth G. | Kropff, Martin J.
A field-derived relationship between maximum single leaf net photosynthetic rate under saturating light (Aₘₐₓ) and leaf N content per unit leaf area (Nₐ) is not available for rice (Oryza sativa L.). The rice simulation model ORYZA1 estimates aboveground dry matter production based on the relationship between Aₘₐₓ and Nₐ determined previously under greenhouse-growth chamber conditions. The objectives of this study were to establish to relationship between Aₘₐₓ and Nₐ under field conditions and to determine whether the field-derived relationship could improve ORYZA1 estimation of aboveground dry matter production of tropical irrigated rice. Rice plants were grown in the field with different N rates in the 1993 dry season. The Aₘₐₓ and Nₐ were determined at 38 and 88 d after transplanting. Aboveground dry matter was determined at physiological maturity. Dry matter production data at physiological maturity from four other field experiments were used for model evaluation. There was a close correlation between Aₘₐₓ and Nₐ under field conditions (r² = 0.88). Compared with the relationship between Aₘₐₓ and Nₐ as determined under greenhouse-growth chamber conditions in previous studies, higher Aₘₐₓ was observed at low Nₐ in this field study. When the field-derived relationship between Aₘₐₓ and Nₐ was used, ORYZA1 estimation of dry matter production was improved for rice grown in tropical irrigated environments. Contribution from IRRI.
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