利用可精准控制CO2浓度的大型人工气候室,探讨提高CO2浓度和温度对玉米生长、气体交换参数、荧光参数及水分利用效率的影响。结果表明,温度显著影响玉米的生长过程,但CO2浓度对玉米的生物量、叶面积和株高的变化均未产生显著影响。另外,在25/19℃和31/25℃温度条件下,净光合速率(Pn)对温度的响应并没有受到CO2浓度的影响,但在37/31℃高温环境下,CO2浓度升高导致玉米的Pn显著提高16.4%(P<0.05),表明在高温条件下,升高CO2浓度能增加玉米的净光合速率。此外,玉米叶片的水分利用效率(water use efficiency,WUE)随温度升高而显著下降,但CO2浓度升高条件下的玉米叶片WUE明显高于自然CO2浓度,表明CO2浓度升高可以降低升温对玉米叶片WUE的影响。但在不同环境温度条件下,CO2浓度升高缓解高温对叶片WUE产生影响的机理存在差异,较低温度时CO2浓度升高通过降低叶片的蒸腾速率提高WUE,而在高温条件下主要是由于CO2浓度升高能有效缓解高温对Pn的伤害,进而促进叶片WUE的提升。研究结果可为深入理解未来气候变化对玉米生长及水分利用效率产生的影响提供参考,为应对气候变化的农田管理策略制定提供数据支撑和理论依据。 相似文献
In the ESPACE-Wheat programme, 25 open-top chamber experiments were carried out in 1994, 1995 and 1996, on nine locations, divided over eight European countries. In most experiments, spring wheat cv. Minaret was subjected to two levels of atmospheric CO2 and two levels of ozone. Grain yields in the control treatments (ambient levels of CO2 and O3) varied strongly between sites. Also, yield response to elevated CO2 and O3 showed great variation. The present study was conducted to determine whether climatic differences between sites could account for the observed variation.
Two simulation models were used for the analysis: AFRCWHEAT2-O3 and LINTULCC. AFRCWHEAT2-O3 simulates phenology, canopy development and photosynthesis in greater detail than LINTULCC. Both models account for the effects of radiation and temperature on crop growth. New algorithms were developed to simulate the effects of CO2 and O3. Weather data that were measured in the experiments were used as input, and simulated growth responses to CO2 and O3 were compared with measurements. No attempt was made to merge the two models. Thus two independent tools for analysis of data related to climate change were developed and applied.
The average measured grain yield in the control treatment, across all 25 experiments, was 5.9 tons per hectare (t ha−1), with a standard deviation (SD) of 1.9 t ha−1. The models predicted similar average yields (5.5 and 5.8 t ha−1 for AFRCWHEAT2-O3 and LINTULCC, respectively), but smaller variation (SD for both models: 1.2 t ha−1). Average measured yield increase due to CO2-doubling was 30% (SD 22%). AFRCWHEAT2-O3 expected a slightly lower value (24%, SD 9%), whereas LINTULCC overestimated the response (42%, SD 11%). The average measured yield decrease due to nearly-doubled O3 levels was 9% (SD 11%). Both models showed similar results, albeit at lower variation (7% yield decrease at SDs of 6 and 4%). Simulations accounted well for the observation that, at elevated CO2, the percentage yield loss due to O3 was lower than at ambient CO2.
The models predicted lower variation among sites and years than was measured. Yield response to CO2 and O3 was predicted to depend on the climate, with a predominant effect of temperature on the response to CO2. In the measurements, these climatic effects were indeed observed, but a greater part of the variation was not related to light intensity, temperature, CO2, or O3. This unexplained variability in the measured dataset was probably caused by factors not accounted for in the models, possibly related to soil characteristics.
We therefore conclude that even perfect information on the climate variables examined in ESPACE-Wheat, i.e. light intensity and temperature, by itself would be insufficient for accurate prediction of the response of spring wheat to future elevated levels of CO2 and O3. 相似文献
Elevated CO2 (eCO2) concentrations can stimulate crop growth, but little is known about intraspecific variability in the response to eCO2 and the underlying genetics in cereals. Field experiments over two years with 98 barley genotypes were conducted in open‐top chambers (OTCs) under ambient CO2 (400 ppm) and eCO2 (700 ppm) concentrations. At crop maturity, different fractions of aboveground biomass (AGB) were measured, and genome‐wide association studies (GWASs) were conducted to identify quantitative trait loci (QTL). Averaged across all genotypes, eCO2 significantly enhanced AGB by 15%, while the increase in culm and ear biomass alone was not significant. The AGB response to eCO2 of the individual genotypes ranged from c. ?36% to +95% compared with ambient CO2 (aCO2), showing a large variability of growth responses. In GWAS, 51 associations between SNP markers and the relative changes (eCO2/aCO2) in biomass were detected on different chromosomes. Loci potentially involved in biomass alterations under eCO2 were identified. The wide range of variability in responses might be exploited by marker‐based breeding for climate‐resilient barley. 相似文献