CO2加富与两种供N水平对非洲菊光合生理及生长发育的影响

Interactive effects of elevated CO_2 and two nitrogen levels supply on photosynthetic physiology and plant growth in Gerbera jamesonii

CO_2加富会促进植物的光合作用和生长发育,但长期的CO_2加富常因植物较低的氮(N)含量而降低这种促进作用。本文在大气CO_2浓度(40 0μmol·mol-1)和CO_2加富(800μmol·mol-1)条件下,研究不同N水平(15 mmol·L-1和30 mmol·L-1)对非洲菊光合生理和生长发育的影响。结果表明,CO_2加富显著提高非洲菊叶片的净光合速率,在整个试验期间CO_2800+N15比CO2400+N 1 5平均增加3 5%;CO_2800+N 3 0平均比CO2400+N 3 0增加了6 5%;在试验末期,CO_2800+N 3 0显著大于CO_2800+N15。非洲菊叶片中可溶性糖和淀粉含量在CO_2加富条件下显著增加,但随着试验处理时间的延长,CO_2800+N30的增加趋势小于CO_2800+N15;CO_2加富降低了非洲菊叶片中蛋白质和N含量,N的增加则缓解了这一下降趋势;在生长发育方面,CO_2加富不但促进了非洲菊的生长,而且提前了非洲菊的花期,增加了非洲菊的花朵数目,增大了花朵直径,增粗了花梗,增加了花朵花色素苷含量,显著提高了非洲菊的观赏品质。同时,增加的N与CO_2互作对非洲菊花部品质也有显著促进作用。以上数据表明,在非洲菊的栽培中,增加CO_2浓度的同时,提高N肥的供给是非常必要的。

Elevated carbon dioxide（CO_2） is widely reported to stimulate the plant growth. However, plants grown under elevated CO_2 typically have decreased tissue concentrations of N compared with plants grown under current ambient CO_2. Herein, studies on photosynthetic physiology and growth of G erbera jamesonii were conducted in the greenhouses under the combined conditions of two CO_2 concentrations（approximately 400 and 800 μmol·mol-1） and two nitrogen level（15 and 30 mmol·L-1）. The results showed that the leaf net photosynthetic rate（Pn） of G. jamesonii was averagely increased by 35% in CO_2800＋N15 and by 65% in C O_2800＋N30 compared with CO_2400＋N15 and CO_2400＋N30, respectirely, which was remarkably higher in CO_2800＋N30 than that in CO_2800＋N15 in the later period of the experiment. Meanwhile, elevated CO_2 promoted the accumulation of soluble sugar and starch in G. jamesonii leaves, but the increased ratio in CO_2800＋N15 was slightly declined during the following experiment period, and CO_2800＋N30 might alleviate the phenomenon. Elevated CO_2 decreased the contents of soluble proteins and nitrogen, but nitrogen application had beneficial effect on the contents of soluble proteins and nitrogen in G. jamesonii leaves under elevated CO_2 conditions. The growth parameters revealed that elevated CO_2 combined with nitrogen level not only significantly promoted growth and biomass accumulation in G. jamesonii, but also promoted earlier flowering, augmented the flower number and size, increased the peduncle diameter, accumulated anthocyanin concentrations, and prolonged the flower vase life. The above results suggest that the increasing supply of CO_2 and nitrogen at the same time would be very necessary in production of G. jamesonii.