CO2浓度升高对不同秋眠类型苜蓿生长发育的影响

为了分析3种秋眠类型苜蓿(Medicago sativa)(秋眠型苜蓿Maverick、半秋眠型苜蓿ABI700和极非秋眠型苜蓿UC-1465)在不同CO_2浓度下的生长发育情况,本研究运用人工气候箱和开顶式气室动态观测了3种秋眠类型苜蓿的种子发芽特性、生长发育和产量大小。主要结果:1)550、700μmol·mol-1 CO_2浓度处理能显著提高3种秋眠类型苜蓿种子的发芽率、发芽势和发芽指数(P0.05),缩短平均发芽天数(P0.05)。其中550μmol·mol~(-1)浓度处理下苜蓿种子的发芽率、发芽势最高。2)高CO_2浓度促进3种秋眠类型苜蓿生育期提前3~6d,且CO_2浓度越高生育期越提前。3)高CO_2浓度能显著促进3种秋眠类型苜蓿株高、叶面积和单株干重增加(P0.05)。高CO_2浓度处理后UC-1465的单株鲜重比Maverick高19.33%~21.76%,比ABI700高12.74%~13.11%;单株干重比Maverick高14.85%~26.77%,比ABI700高12.31%~14.58%,高CO_2浓度处理后极非秋眠型苜蓿UC-1465生长优势进一步提高。4)CO_2浓度对苜蓿茎粗无显著影响(P0.05),但促进秋眠型苜蓿Maverick、半秋眠型苜蓿ABI700茎粗增大。上述结果表明,在一定浓度范围内,苜蓿种子的发芽率、发芽指数、发芽势、株高、叶面积、生物量等对CO_2的响应存在浓度效应。可以预测,未来大气CO_2浓度升高的对苜蓿生长有一定的促进作用,具有一定的应用潜力。

Effects of elevated CO2 on growth and yield of different fall dormancy alfalfa

This study was conducted to determine the growth and development of three types of fall dormancy alfalfa (fall dormancy alfalfa Maverick,semi-fall dormancy alfalfa ABI700,and non-fall dormancy alfalfa UC-1465) under elevated CO2 concentration.We used an artificial climate box and open top chamber dynamic and observed seed germination,growth,and yield of three types of fall dormancy alfalfa.The results showed the following:1) The germination rate,germination potential,germination index,and mean germination time of all three types fall dormancy alfalfa were promoted significantly when CO2 concentrations reached 550-700 μmol · mo1-1.2) Under high CO2 concentration,the growth period of the three types of alfalfa increased with CO2 concentration after 3～6 d.3) The plant height,leaf area,fresh weight,and dry weight increased significantly under high CO2 concentration (P＜0.05).The fresh weight of single plant of UC-1465 was greater than Maverick and ABI700 by 19.33％～21.76％ and 12.74％～13.11％,respectively,after high CO2 concentration treatment.The dry weight per plant of UC-1465 was also greater than Maverick and ABI700 by 14.85％ ～ 26.77％ and 12.31％～14.58％,respectively,after high CO2 concentration treatment,while the growth advantage of the non-fall dormancy alfalfa UC-1465 was further improved.4) CO2 concentration had no significant effect on the stem diameter except at flowering (P ＞0.05).The stem diameters of Maverick and ABI700 during the whole growth period were larger than those of the control group under high CO2 concentration.These results suggest that the growth potential of the non-fall dormancy alfalfa and semi-fall dormancy alfalfa would be greater in the future under conditions of elevated atmospheric CO2 concentration.