Improving nitrogen-use and radiation-use efficiencies of C4 summer cereals by split nitrogen applications under an irrigated arid environment.

Increasing resource-use efficiency is of prime importance in sustainable agriculture. A field study was carried out to improve nitrogen-use efficiency (NUE) and radiation-use efficiency (RUE) of three C₄ summer cereals, i.e. maize, millet, and sorghum, under an irrigated arid environment. The results showed that among various cultivars of cereals, cultivars Pearl (maize), 18 BY (millet), and Jumbo (sorghum) produced the highest aboveground total dry matters and grain yields. The highest NUE and RUE were obtained by splitting the nitrogen dose 3 times, i.e. at sowing and at first and second irrigation. The NUE for maize, millet, and sorghum varied from 30.97 to 32.97, 21.34 to 23.32, and 17.39 to 20.22 kg kg^-1, respectively. RUE ranged from 1.14 to 1.47, 0.85 to 1.08, and 0.91 to 1.13 g MJ^-1 for maize, millet, and sorghum crops, respectively. Maximum resource-use efficiency was achieved by 3 splits, while the minimum was obtained in the control group. It is inferred from this study that those varieties of C₄ summer cereals may be commercially grown that are more efficient in utilizing the available resources for harnessing greater NUE as well as RUE under an irrigated arid environment. [ABSTRACT FROM AUTHOR]