Abstract:

In order to explore the response characteristics of leaf photosynthetic characteristics, photosynthetic nitrogen use efficiency and yield of super hybrid rice to different nitrogen application rates, a field experiment with rice cultivar Q you 6（V1） and Yixiangyou 2115 （V2） as materials was conducted under the conditions of different nitrogen application rates in Huangping county, Guizhou Province in 2019. The results showed that with the increase of nitrogen application rate, at booting stage, maximum electron transfer rate （J_max） and nitrogen content per leaf area （N_area） showed an upward trend, apparent quantum efficiency （AQE）, leaf net photosynthetic rate （P_n）and photosynthetic nitrogen utilization efficiency（PNUE）（except N0 treatment） increased first and then decreased, while light compensation point （LCP）, intercellular CO₂ concentration （C_i） were just opposite. At the heading stage, stomatal conduction to CO₂（G_s）, LCP and N_area increased first and then decreased, while PNUE showed opposite trend. Moreover, the spikelet per panicle and the harvest yield first increased and then decreased with the increase of nitrogen application rate, while the spikelet number per panicle showed an upward trend, 1 000-grain weight and seed setting rate showed opposite trend. With the increase of nitrogen application rate, at the booting stage, P_n, N_area and AQE of V1 increased first and then decreased, and C_i had the opposite trend. P_n, Narea and AQE of V2 showed an upward trend, and C_i showed a downward trend. At the heading stage, the N_area of the two varieties showed an upward trend, and the LCP showed a trend of rising first and then declining. In addition, with the increase of nitrogen application rate, the change trend of the yield and its constituent factors of the two varieties was the same. Both the 1 000-grain weight and seed setting rate showed a downward trend, and the harvest yield exhibited first increased and then decreased. Between the two varieties, the PNUE at booting stage, P_n and N_area and PNUE at heading stage, 1 000-grain weight and seed setting rate of V2 were significantly higher than those of V1, while spikelet number per panicle and harvest yield were opposite. Under the experimental conditions, the regression analysis results showed that the nitrogen application rate of the highest yield of Q you 6 was 188.13 kg/hm² and the highest yield was 13 237.89 kg/hm²; the nitrogen application rate of the highest yield of Yixiangyou 2115 was 107.16 kg/hm² and the highest yield was 10 027.35 kg/hm². In short, under the experimental conditions, increasing nitrogen application rate in the range of 75~225 kg/hm² nitrogen application rate could promote stomata opening and CO₂ absorption of leaves to participate in photosynthesis, thus promoting the transformation of CO₂ into stable carbohydrate in the substrate, improving photosynthetic rate and photosynthetic nitrogen use efficiency of leaves, so as to achieve high yield.

Key words: rice, nitrogen application rate, photosynthetic characteristics, photosynthetic nitrogen use efficiency, yield

摘要：

为探明超级杂交稻叶片光合特性、光合氮素利用效率和产量对不同施氮量的响应特征,以Q优6号（V1）、宜香优2115（V2）为材料,于2019年在贵州省黄平县进行了不同施氮量的田间试验。结果表明,随着施氮量的增加,在孕穗期,最大电子传递速率（J_max）和单位叶面积氮含量（N_area）呈上升趋势,表观光量子效率（AQE）、净光合速率（P_n）和光合氮素利用效率（PNUE）（除N0处理外）呈先升后降趋势,而光补偿点（LCP）和胞间二氧化碳浓度（C_i）表现相反;在抽穗期,气孔导度（G_s）、LCP和N_area呈先升后降趋势,而PNUE呈相反趋势。每穗粒数和实际产量随着施氮量的增加呈先升后降趋势,而有效穗数呈上升趋势,千粒重和结实率呈下降趋势。随着施氮量的增加,在孕穗期,Q优6号的P_n、N_area和AQE呈先升后降趋势、C_i与之相反,宜香优2115的P_n、N_area和AQE呈上升趋势、C_i呈下降趋势;在抽穗期,两个品种的N_area均呈上升趋势,LCP均呈先升后降趋势。此外,随着施氮量的增加,两个品种产量及其构成因子变化趋势一致,千粒重和结实率均呈下降趋势,实际产量呈先升后降趋势。两个品种间,水稻孕穗期的PNUE,抽穗期的P_n、N_area和PNUE,以及千粒重和结实率均为宜香优2115显著高于Q优6号,每穗粒数和实际产量表现相反。在本试验条件下,回归分析结果表明,Q优6号获得最高产量的施氮量为188.13 kg/hm²,最高产量可达13 237.89 kg/hm²;宜香优2115获得最高产量的施氮量为107.16 kg/hm²,最高产量可达10 027.35 kg/hm²。总的来说,在75~225 kg/hm²的施氮量范围内,增施氮肥能促进叶片气孔张开和吸收CO₂参与光合作用,促进CO₂转化成稳定的碳水化合物,同时提高叶片光合速率和光合氮素利用效率,进而实现高产。

关键词: 水稻, 施氮量, 光合特性, 光合氮素利用效率, 产量