Crop Improvement for Nitrogen Use Efficiency in Irrigated Lowland Rice

Abstract

There is an urgent need to develop superior nitrogen -effi cient rice varieties because of poor fertilizer nitrogen use effi ciency (NUE), associated economic and environmental concerns, and the lack of adoption of improved nitrogen management practices. Genotypic variation in NUE has been reported for rice in many studies. The physiological mechanisms underlying both nitrogen uptake effi ciency and utilization effi ciency are fairly well understood. Plant traits that are closely associated with NUE have been identifi ed. In general, there is a positive relationship between grain yield and NUE, suggesting that it is possible to develop rice varieties with both high grain yield and high NUE. An empirical breeding method can be used for developing nitrogeneffi cient varieties using existing genotypic variation in NUE. However, for signifi cant improvement in NUE, new breeding techniques such as the development of F 1 hybrids, marker -aided selection, transformation, and genetic engineering should be considered.

Increasing the Growth and Production of Irrigated Rice Through the Integrated Application of Rice–Duck–Azolla

“…The application of nitrogen fertilizer without ducks or Azolla reduced the ability of the plants to absorb nitrogen and increased nitrogen loss, thereby reducing the growth and production of the rice plants. The intensive use of inorganic nitrogen in high doses reduced the productivity of rice plants as there was a decrease in the ability of the plants to absorb and use nitrogen (Peng, 2011). The application of ducks and Azolla without nitrogen fertilizers were not able to provide the nitrogen required by rice plants.…”

“…Modern agriculture requires high external inputs, such as inorganic fertilizers and pesticides (Reijntjes et al, 1992), and leads to water, soil, and air pollution, which does not support the concept of sustainable agriculture (Peng, 2011). In addition, modern agriculture can also increase production costs and reduce farmers' incomes (Reijntjes et al, 1992).…”