Abstract:

Nitrogen is the most demanded nutrient element for rice, but excessive application of nitrogen can easily lead to a mismatch between rice growth and the availability of light−temperature resources, which is becoming one of the factors limiting the high yield and quality of rice. In this study, used three high−quality rice as variety materials, 5 nitrogen application amount (N₀: 0, N₁₂₀: 120kg·ha⁻¹, N₁₅₀: 150kg·ha⁻¹, N₁₈₀: 180kg·ha⁻¹ and N₂₁₀: 210kg·ha⁻¹) were set to analyze the effect of different nitrogen levels on light−temperature utilization, yield and grain quality of rice. The aim was to provide a reference for enhancing yield potential and optimizing the utilization of climate resource for high−quality rice cultivation in northern Jiangxi. The results showed that with the increase of nitrogen amount, the whole growth period of the tested high−quality rice in 2023–2024 was prolonged by 4−11d and 4−13d respectively, and the prolongation mainly occurring in the reproductive growth stage. The ≥10°C accumulated temperature and solar radiation during the whole growth period generally showed an increasing trend, the increase range of ≥10°C accumulated temperature was 2.5%−8.7% in 2023 and 2.6%−11.4% in 2024, increase range of solar radiation was 1.1%−8.3% in 2023 and 2.0%−9.1% in 2024. The ≥10°C accumulated temperature production efficiency, light production efficiency and light utilization efficiency first increased and then decreased, maximized in N₁₅₀ treatment. The grain number per panicle and yield maximized under N₁₅₀ treatment, while the seed setting rate showed a decreasing trend, and the effective panicle increased with the increase of nitrogen rate. Rice processing quality was best in N₁₅₀ treatment; appearance quality decreased with the increase of nitrogen rate; amylose content first decreased and then increased, both ‘YXYLS’ and ‘TFY308’ lowest in N₁₅₀ treatment. gel consistency first increased and then decreased, except for ‘YXYLS’ maximized in N₁₈₀ treatment in 2023, all other treatments maximized in the N₁₅₀ treatment. Overall, both high yield, good quality and high light−temperature utilization rate can be obtained by applying 150kg·ha⁻¹ in whole growth period. This nitrogen rate is recommended for high−quality indica rice in northern Jiangxi.

Key words: Nitrogen rate, High?quality rice, Yield, Grain quality, Light?temperature utilization