关键词: 水稻, 施氮量, 光合特性, 光合氮素利用效率, 产量

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