模拟大气温度和CO2浓度升高对双季稻氮素利用的影响

摘要

Preventing 2°C of warming and restricting the CO2 level to 450 µL L–1 are the safety threshold for climate change based on the Copenhagen Consensus. It is an important reference for the security of rice yield to study the influence of elevated air temperature and CO2 concentration on the nitrogen use of rice. In this paper, a modified open-top chamber (OTC) device was used to simulate relative 60 µL L–1 CO2 concentration rise (based on CO2 background concentration of 390 µL L–1) and 2°C tempera-ture increase scenario in a double rice field experiment with Liangyou 287 and Xiangfengyou 9 as the early and late rice varieties respectively. There were five treatments with three replications: 1) UC: Paddy field without OTC cover; 2) CK: Check OTC with the similar temperature and CO2 concentration to the field environment; 3) CT: OTC with 2°C temperature increase; 4) CC: OTC with 60 µL L–1 CO2 concentration elevated; 5) CTC: OTC with 2°C temperature increase and 60 µL L–1 CO2 concentration ele-vated. The nitrogen accumulation, translocation and utilization in different treatments were explored. The results showed signifi-cant interactions between temperature increase and CO2 concentration elevated on the yield and nitrogen use. In early rice CC and CTC achieved an increase for grain yield (19.7% and 2.0%) and nitrogen accumulation (15.7% and 5.1%) compared with CK while CT presented a decrease. In late rice warming and high CO2concentration (CT, CC, and CTC) benefited the grain yield and nitrogen uptake, increasing 9.2%, 14.4%, 18.8% and 7.3%, 10.2%, 15% compared with CK respectively. Nitrogen translocation and contribution efficiency (from stem and leaf to grain) of CC and CTC was lower than that of CK in early rice, and higher than that of CK in late rice. Nitrogen recovery efficiency of CC and CTC reached to 45.7% and 48.5% in early and late rice respec-tively, achieving the highest increase of 35.3% and 33.1% compared with that of CK. CC and CTC got the highest nitrogen agro-nomic efficiency by 23.1 kg kg–1 and 26.9 kg kg–1 in early and late rice respectively, and CC got the highest nitrogen physiological efficiency by 50.7 kg kg–1 and 56 kg kg–1 in both early and late rice. There existed no significant difference between CK and UC, which suggested the impact on rice growth under OTC covering was slight. In conclusion, it tends to a negative effect with 2°C temperature increase on yield and nitrogen utilization for early rice, while a positive effect for late rice. A positive effect with 60 µL L–1 CO2 concentration elevated always exists during double rice growth. The condition of 2°C temperature increase and 60 µL L–1 CO2 concentration elevated has an antagonistic effect on early rice, while a synergistic effect on late rice.%未来气候主要表现为大气温度和CO2浓度升高的变化趋势,升温2℃和CO2浓度达到450µL L–1(同比增加60µL L–1)情景是哥本哈根共识下的安全阈值。本研究采用自主研制的开顶式气室(open-top chamber, OTC)进行双季稻大田原位模拟试验,以早稻两优287和晚稻湘丰优9号为试验材料,设置了大田(UC)、对照(CK)、增温2℃(CT)、增CO260µL L–1(CC)和同时增温2℃增CO260µL L–1(CTC)5个处理,研究温度和CO2浓度升高对双季稻产量和氮素利用的影响。结果表明,早稻CT的籽粒产量和氮素积累量均低于CK, CC和CTC比CK提高籽粒产量19.7%和2.0%,提高氮素积累量15.7%和5.1%；晚稻CT、CC和CTC籽粒产量和氮素积累量比CK分别提高9.2%、14.4%和18.8%,及7.3%、10.2%和15%。茎叶氮素转运率和贡献率早稻CC和CTC略低于CK,晚稻CC、CTC均高于CK。氮素吸收利用率早稻以CC最高(45.7%),晚稻以CTC最高(48.5%),分别比CK提高了35.5%和33.1%。氮素农学利用率与之一致,早稻和晚稻的CC和CTC均最高(23.1 kg kg–1和26.9 kg kg–1),比CK提高了56.3%和46.2%。氮素生理利用率早稻和晚稻均以CC最高,相比CK提高了12.7%和10.5%,但差异不显著。CK与UC之间各项指标差异不大,这表明OTC覆盖对水稻生长造成的影响在可接受误差之内。综上所述,本研究认为温度升高2℃对早稻产量和氮素利用倾向于不利影响,对晚稻则相反； CO2浓度增加60µL L–1对早稻和晚稻产量和氮素利用倾向于有利影响；同时增温和增CO2对早稻表现抵消作用,对晚稻表现协同作用。