大气CO2浓度升高对谷子生长发育及玉米螟发生的影响

人类活动导致全球大气CO_2浓度持续升高,研究大气CO_2浓度升高对C4作物谷子(Setaria italica)生长发育及虫害发生的影响,可以为谷子等C4作物制订应对气候变化栽培措施提供理论依据。本研究利用OTC(Open Top Chamber)系统,设两个CO_2浓度梯度(正常大气CO_2浓度、正常CO_2浓度+200μmol·mol-1)模拟CO_2浓度升高对谷子生长发育的影响。结果表明:大气CO_2浓度升高后,谷子净光合速率(Pn)、气孔导度(gs)、叶片蒸腾速率(Tr)和水分利用率(WUE)分别增加38.73%、27.53%、6.93%和40.56%;谷子叶片光系统Ⅱ最大光化学量子产量(Fv/Fm)和非光化学淬灭系数(NPQ)显著下降,光系统Ⅱ实际光化学量子产量(ΦPSII)和表观电子传递效率(ETR)显著增加,而对光化学淬灭系数(q P)无显著影响;此外,谷子株高、茎粗和小穗数分别增加3.41%、13.28%和13.11%;而叶重、茎重、千粒重、单株粒数和产量无显著变化,穗重和地上部分生物量分别显著下降12.8%和7.44%;大气CO_2浓度升高后,谷子灌浆期和收获期玉米螟(Ostrinia furnacalis)发生数量显著增加。大气CO_2浓度升高将有利于谷子的生长发育,但会增加玉米螟危害。

Effect of elevated[CO2] on growth and attack of Asian corn borers (Ostrinia furnacalis) in foxtail millet (Setaria italica)

Since industrial revolution, global atmospheric carbon dioxide (CO2) concentration (CO2]) has risen from 280mmol·mol–1 to the current level of about 392mmol·mol–1. Foxtail millet (Setaria italica) is one of the most important C4 crops in the semiarid regions of North China, yet there is lack of sufficient information on how the crop responds to climate change in China. Here, we studied the effects of elevated atmospheric CO2] on foxtail millet in order to understand the changes in foxtail millet production under future CO2 concentrations along with the response of C4 crops to climate change. An open top chamber (OTC) system was used to test the effect of elevated CO2] on foxtail millet. One OTC was used as the control chamber, which maintained the ambient CO2]. In another OTC, elevated CO2] (ambient CO2] + 200 mmol×mol–1) was constantly maintained from crop emergence to harvest. Foxtail millet was sown in 40 cm × 60 cm pots (28 cm depth). Ten plants were grown in each pot and 10 pots were put in every OTC. Leaf photosynthesis was measured using a portable gas exchange system. Chlorophyll fluorescence parameter was assessed using a miniaturized pulse-amplitude modulated fluorescence analyzer with a leaf clip holder. The changes in morphological parameters, biomass, yield and damage of Asian corn borer (Ostrinia furnacalis) in response to elevated CO2] were also determined. The results showed that elevated CO2] increased the net photosynthesis rate (Pn), stomatal conductance (gs), transpiration rate (Tr) and water use efficiency (WUE) of foxtail millet by 38.73%, 27.53%, 6.93% and 40.56%, respectively. The maximal photochemical quantum yield (Fv/Fm) and non-photochemical quenching coefficient (NPQ) of foxtail millet leaf photosystem Ⅱ significantly decreased under elevated CO2]. Photosystem Ⅱ quantum yield (ΦPSII) and apparent electron transfer rate (ETR) increased, but the change in photochemical quenching destruction coefficient (qP) was not significant. Elevated CO2] increased foxtail millet plant height, stem diameter and spikelet number by 3.41%, 13.28% and 13.11%, respectively. Elevated CO2] did not significantly affect leaf mass, stem mass, thousand-seed weight or the number of grain per plant at harvest, but the mass of panicle and aboveground per m2 significantly decreased by 12.8% and 7.44%, respectively. Furthermore, Asian corn borer damage aggravated at filling-stage and harvest under elevated CO2]. However, yield did not significantly change under elevated CO2]. In conclusion, elevated atmospheric CO2] promoted the growth and development of foxtail millet, but increased the risk of insect damage.