Nitrogen Application in Irrigated Rice Grown in Mediterranean Conditions: Effects on Grain Yield, Dry Matter Production, Nitrogen Uptake, and Nitrogen Use Efficiency

ABSTRACT

Field experiments were conducted in the major rice growing area of Chile to evaluate the effects of nitrogen (N) fertilization and site on grain yield and some yield components, dry matter production, N uptake, and N use efficiency in rice cultivar ‘Diamante’. Two sites (indicated as sites 1 and 2) and six N rates (0, 50, 100, 150, 200, and 300 kg N ha⁻¹) were compared. Nitrogen fertilization increased yield, panicle density, spikelet sterility, dry matter production, and N uptake at maturity. 90% of maximum yield was obtained with 200 kg N ha⁻¹ in site 1 (12,810 kg ha⁻¹) and with 100 kg N ha⁻¹ in site 2 (8,000 kg ha⁻¹). These differences were explained by lower panicle density, and the resulting lower dry matter production and N uptake in site 2. Nitrogen use efficiency for biomass and grain production, and grain yield per unit of grain N decreased with N fertilization. While, agronomic N use efficiency and N harvest index were not affected. All N use efficiency indices were significantly higher in site 1, except grain yield per unit of grain N. The observed variation in N use efficiency indices between sites would reflect site-specific differences in temperature and solar radiation, which in turn, determined yield potentials of each site. On the basis of these results, cultivar ‘Diamante’ would correspond to a high-N use efficiency genotype for grain yield.

Keywords:

• irrigated rice
• nitrogen use efficiency
• dry matter production
• nitrogen uptake
• Mediterranean conditions
• Chile

ACKNOWLEDGMENTS

The authors wish to thank Dr. Tania Zaviezo from Universidad Católica de Chile for critical revision of the manuscript. This research was supported by “Programa de Desarrollo de Proveedores” Tucapel Companies – Pontificia Universidad Católica de Chile.

Notes

¹Base temperature = 10°C.

¹Regression equation was linear.

∗,

∗∗ = significant at the 0.05 and 0.01 probability levels, respectively; ns = not significant.

¹Leaves, sheaths and culms.

²Caryopsis and hull

³Regression equation was linear.

∗,

∗∗ = significant at the 0.05 and 0.01 probability levels, respectively.

¹Because the effect of N was not significant, no regression analysis was conducted.

∗,

∗∗ = significant at the 0.05 and 0.01 probability levels, respectively.