Is the Two-Line Hybrid Rice a Hindrance to the Efficient Use of Nitrogen Fertilizer in China?

Abstract

Two-line hybrid rice (2LH) is accompanied by more nitrogen (N) input. To explore the difference in response of two-line and three-line hybrid rice (3LH) to N application, a three-year split-plot experiment was conducted. Three 2LHs and three 3LHs were set as main plots, and four N rates including 0 kg ha−1 (N0), 90 kg ha−1 (N90), 150 kg ha−1 (N150), and 210 kg ha−1 (N210) were set as subplots. 3LH had more panicles and yielded 7.95%, 6.31%, and 5.48% higher than 2LH in N0, N90, and N150, respectively. 2LH had a greater panicle weight in N210 and yielded 1.45% higher than 3LH. Leaf area index (LAI) had the greatest effect on the yields of both 2LH and 3LH, while the contribution of light extinction coefficient (K) was 46.35% and 12.80% those of LAI, respectively. The LAI, K, and radiation interception rate (RIR) of 2LH were smaller than those of 3LH in N0 and N90. The K of 2LH increased significantly as the N rate increased from 150 kg ha−1 to 210 kg ha−1, while that of 3LH showed no significant change, making the maximum RIR of 2LH greater than that of 3LH. 2LH, which intercepted more radiation through greater leaf extension to achieve higher yields, was able to use nitrogen fertilizer efficiently under a high N rate in China.

Optimizing Irrigation and Nitrogen Regimes in Rice Plants Can Contribute to Achieving Sustainable Rice Productivity

“…It tends to be relatively consistent when N rates are similar for a specific rice variety in the same climatic environment [15]. For example, the B/Nr is around 100 g g −1 and 110 g g −1 for the japonica and indica rice variety, respectively, when the N rate is 180-300 kg ha −1 in the rice fields of East China [31]. Increasing NUE (NUEg, internal N use efficiency) in cereals requires varieties with high HI, which is commonly recognized by agronomists [15].…”