增温对苜蓿物候和产草量的影响

Effects of Warming on Alfalfa Phenology and Grass Yield

利用红外线辐射器模拟增温,研究增温对苜蓿物候和产草量的影响,以期为未来气候变暖条件下苜蓿产草量的预测提供理论依据。结果表明,与常温对照相比,增温处理土壤温度平均增加0.7℃、湿度降低11.3%;增温处理苜蓿的幼苗期、分枝期、现蕾期、初花期、盛花期分别显著提前2.0、5.8、8.7、9.0、3.3 d;增温处理苜蓿叶片的净光合速率显著降低13.2%,产草量显著降低13.8%;增温处理苜蓿根部总氮、总碳含量分别显著降低7.4%、11.8%,土壤中总氮含量显著降低4.5%。相关和回归分析发现,苜蓿播种至盛花期的时间和产草量均随着土壤中总氮含量的升高呈显著线性增加的趋势。这表明,在未来气候变暖的背景下,随着土壤中氮含量的减少,苜蓿的开花期会提前,产草量将会降低。

A simulated warming experiment using infrared radiators was conducted to study the effects of climate warming on phenology and grass yield of alfalfa,so as to provide the theoretical basis for grass yield prediction in the future climate warming conditions. The results indicated that warming increased mean soil temperature by 0. 7 ℃,and reduced mean soil moisture by 11. 3%,compared with the control（ normal temperature treatment）. Warming significantly accelerated alfalfa seedling,branching,budding,early flowering,and flowering stages by 2. 0,5. 8,8. 7,9. 0 and 3. 3 days,respectively. Warming significantly decreased leaf net photosynthetic rate by 13. 2%,and reduced grass yield by 13. 8%. Moreover,warming significantly decreased root nitrogen and carbon content by 7. 4% and 11. 8%,respectively,and reduced soil nitrogen content by 4. 5%. The correlation and regression analysis showed that the time when alfalfa reached flower stage and grass yield of alfalfa showed significantly linear increase trends with the increase of soil nitrogen content,respectively. This indicated that flowering stage of alfalfa may advance,and grass yield would reduce with the decrease of soil nitrogen content under future climate warming scenarios.