Growth and marketable-yield responses of potato to increased CO2 and ozone

Central to the CHanging climate and potential Impacts on Potato yield and quality project (CHIP) was the consideration of the potential impacts of ozone and CO₂ on growth and yield of future European Potato crops. Potato crops, cv. Bintje, were exposed to ambient or elevated ozone; targeted daily average, 60 nl l⁻¹ for 8 h, and ambient or elevated CO_2; targeted 680 μl l⁻¹ averaged over the full growing season, in open top chambers (OTCs) at six European sites in 1998 and 1999, or to elevated CO₂ (550 μl l⁻¹) in Free Air Carbon dioxide Enrichment facilities (FACE) at two sites in both years. Some OTC experiments included 550 μl l⁻¹. Above and below ground biomass were measured at two destructive harvests; at maximum leaf area (MLA) and at final-harvest. Final-harvest fresh weight yields of marketable-size tubers, >35 mm diameter, from ambient conditions ranged from 1 to 12 kg m⁻². There was no consistent (P>0.1) CO₂×O₃ interaction for growth or yield variables at either harvest. No consistent effects of ozone were detected at the maximum-leaf-area harvest. However, at final harvest, ozone had reduced both above-ground biomass and tuber dry weight (P<0.05), particularly of the largest (>50 mm) size class. These yield losses showed linear relationships both with accumulated ozone exposure; AOT40 expressed as nl l⁻¹ h over 40 nl l⁻¹, and with yields from chambered ambient-ozone treatments (P<0.05) but, because of partial confounding between the treatment AOT40s and the ambient-ozone yields in the data, the two relationships were not completely independent. Yields from ambient-ozone treatments, however, explained a significant (P<0.01) amount of the residual variation in ozone effects unexplained by AOT40. When averaged over all experiments, mean dry weights and tuber numbers from both harvests were increased by elevated CO₂. Only green leaf number at the MLA harvest was reduced. The CO₂ responses varied between sites and years. For marketable-size tubers, this variation was unrelated to variation in ambient-CO₂ treatment yields. Yield increases resulting from the 680 μl l⁻¹ and 550 μl l⁻¹ treatments were similar. Thus elevating [CO₂] from 550 to 680 μl l⁻¹ was less effective than elevating [CO₂] from ambient to 550 μl l⁻¹. On average, CO₂ elevation to 680 μl l⁻¹ increased the dry weight of marketable-size tubers by about 17%, which far exceeded the average ozone-induced yield loss of about 5%. The net effect of raising CO₂ and O₃ concentrations on the European potato crop would be an increase marketable yield.     

Effects of elevated carbon dioxide and ozone on potato tuber quality in the European multiple-site experiment ‘CHIP-project’

Potato (Solanum tuberosum L cv. Bintje) was exposed to ambient and elevated carbon dioxide (CO₂), to ambient and elevated ozone (O₃) and to elevated levels of both gases during two growing seasons, 1998 and 1999. Experiments in open-top chambers (OTC) were carried out in Finland, Sweden, Ireland, United Kingdom, Germany and Belgium and a FACE (Free Air Carbon dioxide Enrichment) experiment was carried out in Italy. In OTCs the plants were grown under ambient CO₂ concentrations or with 550 and 680 μl l⁻¹ CO₂ alone or in combination with ambient or elevated O₃ concentrations (target seasonal mean of 60 nl l⁻¹ 8 h per day). In the FACE systems the plants were exposed to ambient or 550 μl l⁻¹ CO₂. In the OTC experiments the reducing sugar content of potato tubers decreased significantly with increased concentration of O₃. The starch content of potato tubers decreased, with negative impact on tuber quality, but the ascorbic acid concentration increased as a function of the AOT40 (The sum of the differences between hourly ozone concentration and 40 nl l⁻¹ for each hour when the concentration exceeds 40 nl l⁻¹ during a relevant growing season). However, simultaneous exposure to elevated CO₂ counteracted the ozone effect. With increase in the CO₂ exposure, glycoalkaloid and nitrate concentrations decreased yielding improved quality, while the citric acid concentration decreased causing a higher risk for discoloration after cooking. The amount of dry matter and starch increased significantly in the FACE experiment.     

CO2 and ozone effects on canopy development of potato crops across Europe

This paper describes the effects of elevated CO₂ (550 and 680 μl l⁻¹) and O₃ (60 nl l⁻¹ O₃ as an 8 h mean), alone or in combination, on canopy development and senescence in potato (Solanum tuberosum L. cv Bintje) across a range of European agro-climatic conditions. The assessments were made within the European CHIP project (CHanging climate and potential Impacts on Potato yield and quality) that was conducted for two growing seasons (1998 and 1999) in free air CO₂ enrichment systems (FACE) and open-top chamber facilities (OTCs) at seven European sites. A comparison of chambered and unchambered experimental plots was included to examine the effects of chamber enclosure. Phenological growth stages, plant height, leaf area index (LAI) and the number of green and yellow leaves were recorded non-destructively throughout the growing season and by a destructive intermediate harvest at maximum leaf area (MLA). In the dynamic growth analysis CO₂ and O₃ effects were studied over three developmental stages: canopy expansion, full canopy and canopy senescence. Chamber enclosures promoted potato crop development (taller plants, more leaves) during the initial growth stages and led to a faster decline of LAI and a higher number of yellow leaves. The growth in ambient plots varied between sites and seasons, as did the scale of the treatment responses. Despite the large background variation, some overall treatment effects could be detected across all sites. Both levels of increased CO₂ reduced final plant height in comparison to ambient concentrations, which indicates a premature ending of the active plant growth. At the stage of full canopy and crop senescence the average number of green leaves was significantly (P<0.05) decreased by 680 μl l⁻¹ CO₂ (OTC experiments) and LAI showed the same tendency (P=0.07). As there was however no indication of a decreased leaf formation during initial growth and at full canopy, this must have been due to an earlier leaf fall. In the FACE experiments LAI had already began to decline at the stage of full canopy at 550 μl l⁻¹ CO₂ but not in ambient CO₂ (DAE×CO₂, P<0.05). These observations strongly indicated that elevated CO₂ induced a premature senescence during full canopy. O₃ did not have an overall detrimental effect on crop development during initial growth nor at full canopy, but did induce a faster reduction of LAI during crop senescence (DAE×O₃, P<0.05). Final plant height was not affected by O₃. There were few CO₂×O₃ interactions detected. There was a suggestion (P=0.06) that O₃ counteracted the CO₂-induced decrease of green leaves at full canopy, but on the other hand during crop senescence the decline of LAI due to elevated O₃ was faster at ambient compared to elevated CO₂ (P<0.05). These responses of canopy development to elevated CO₂ and O₃ help to explain the treatment responses of potato yield within the CHIP project at sites across Europe.     

Changing climate and potential impacts on potato yield and quality ‘CHIP’: introduction, aims and methodology

Climate change effects caused by an increasing concentration of CO₂ and ozone represent an issue of major concern both for scientists and policy-makers. In a concerted program funded by the Commission of the European Union, a European network of experiments (in open-top chambers (OTC), and free air carbon dioxide enrichment systems (FACE)) and modelling was carried out to investigate the effects of increasing atmospheric CO₂ and ozone concentrations, under different climatic conditions, on potato (Solanum tuberosum L. cv. Bintje). This contribution describes the experimental network and the standard protocol set-up for the assessments that served to improve and to validate process oriented potato growth simulation models leading to scenarios of future productivity of potato in Europe.     

Effects of elevated CO2 and/or ozone on nutrient concentrations and nutrient uptake of potatoes

Potato crops were grown at seven sites across Europe to test the effects of elevated atmospheric carbon dioxide and/or tropospheric ozone concentrations on growth, yield and various aspects of potato tuber quality within the framework of the EC funded programme Changing Climate and Potential Impacts on Potato Yield and Quality (CHIP). Field exposure systems were used to enrich the atmosphere in CO₂ and/or ozone. At five of the sites, nutrient element conconcentrations (macronutrients: nitrogen, phosphorus, potassium, calcium, magnesium, and micronutrients: mangenese, zinc, iron) in different parts of plants from the various treatments were analysed. Under elevated CO₂, nearly all nutrient elements tended to decrease in concentration. At maximum leaf area, a significant reduction was observed for the concentrations of nitrogen and potassium both in aboveground biomass and in tubers, and for calcium in tubers. Since CO₂ enrichment promoted early tuber growth, these effects could in part be attributed to tuber developmental stage. At maturity, potato grown under CO₂ enrichment exhibited significantly lower concentrations of nitrogen, manganese and iron in aboveground organs, and of nitrogen, potassium and magnesium in tubers which means a reduction of tuber quality. In contrast to CO₂, elevated ozone tended to increase tuber nutrient element concentrations. This was significant for nitrogen and manganese. CO₂ effects on tuber biomass increase were more pronounced than CO₂ effects on nutrient element decrease. Thus, the total amount of nutrient elements taken up by potato crops increased under elevated CO₂. Fertiliser practice in a future, CO₂-rich world will have to be adjusted accordingly.     

Effect of climatic conditions on tuber yield (Solanum tuberosum L.) in the European ‘CHIP’ experiments

The main objective of the CHIP project was to perform ‘standardised’ investigations of potato (Solanum tuberosum L. cv Bintje) responses to increased O₃ and CO₂ concentrations by means of open-top chambers (OTC) and free air carbon dioxide enrichment (FACE) systems. The experimental sites are located across Europe representing a broad range of different climatic conditions. In 1998 and 1999 a total number of 12 OTC experiments and four FACE experiments were conducted. According to the specific needs for subsequent modelling purposes, environmental data were collected during experiments, i.e. air temperature, global radiation, air humidity (vapour pressure deficit (VPD)), soil moisture and trace gas concentrations. In the present paper, the results of these measurements are summarised. It was shown that the experiments covered a considerable range of growing season mean air temperatures (13.8–19.9 °C) and global irradiances (12.0–21.3 MJ m⁻² per day), the most important driving variables for crop growth simulation models. Analysis of the soils used during the experiments demonstrated that in most cases sufficient nutrient elements were available to guarantee an undisturbed growth. Mean concentrations of CO₂ and O₃ in ambient air and in different treatments illustrate the observed variability of trace gas exposures between different sites and experiments. However, the effects of these parameters on growth and yield are subject of separate papers. The general climatic conditions across Europe are also causing important growth and yield effects. Comparison of marketable tuber yields revealed an increase at higher latitudes. This result was associated with lower temperatures and VPD and longer day lengths at the higher latitudes, which in turn were associated with longer growing seasons.     

Chlorophyll concentration of potatoes grown under elevated carbon dioxide and/or ozone concentrations

Potato cv. Bintje was grown in open-top-chambers and free-air-CO₂-enrichment systems at 7 sites across Europe for 2 years (1998–99). The effect of different treatments (CO₂ enrichment and O₃ fumigation) on the chlorophyll content of fully expanded upper and lower canopy leaves was investigated collecting Minolta SPAD-502 meter readings. In both CO₂ treated and O₃ fumigated plants, leaves had lower chlorophyll content than those in ambient air controls; season-long chlorophyll averages were 9.3% lower in the ‘CO₂’ treatments, 9.1% lower in ‘O₃’ treatments and 12.3% lower in ‘CO₂+O₃’ treatments. The analysis of chlorophyll content in three different growth phases (Emergence–Tuber Initiation; Tuber Initiation–Maximum Leaf Area; Maximum Leaf Area–Harvest) showed that in the early growth period, i.e. before tuber initiation there was a slight indication for an higher chlorophyll content at elevated CO₂ (+3.8%) or O₃ (+1.7%). However, from tuber initiation onwards the leaves of plants grown under elevated CO₂ or O₃ showed a progressively lower chlorophyll content (−4.8% for CO₂ treatments and −2.6% for O₃ treatments) indicating a faster senescence of leaves that increased during the late growth period (−12.8% for CO₂ treatments and −12.7% for O₃ treatments) and that was enhanced by CO₂–O₃ interaction (−17.8%).     

臭氧与其他环境因子及其复合作用对植物的影响

综述了臭氧（O₃）浓度升高、太阳辐射减弱、UV-B辐射、CO₂浓度升高及其与O₃复合作用对植物形态特征、光合作用、干物质累积及作物产量等生理生化机制的影响。交互作用的试验条件可以更好地模拟自然环境条件。O₃和UV-B辐射对植物几乎没有积极作用。太阳辐射减弱、CO₂浓度升高都会促进植物营养生长。但太阳辐射减弱降低干物质累积和产量,CO₂浓度升高对其有促进作用。CO₂浓度升高在与O₃复合条件下,可部分缓解太阳辐射减弱对植物造成的伤害。而UV-B辐射与O₃复合对植物造成的伤害更大。     

生物电化学系统还原二氧化碳产甲烷研究进展

生物电化学系统还原CO2合成燃料或有机化工产品近年来已成为环境微生物学的研究热点。首先就生物电化学系统的工作原理、生物电化学系统还原CO2产甲烷的阴极功能微生物、生物电化学系统还原CO2产甲烷的机制、生物电化学系统的反应器及影响生物电化学系统还原CO2产甲烷的因素等方面的研究进展进行了综述,然后分析了生物电化学系统还原CO2产甲烷存在的问题,并讨论了其今后的重点研究方向,以期为生物电化学系统还原CO2产甲烷研究提供参考。     

蔗糖对不同基因型马铃薯试管苗生长和长期保存的影响

研究不同蔗糖浓度对四个基因型马铃薯试管苗生长和长期保存的影响,为培育马铃薯健壮试管苗和长期保存马铃薯种质资源提供理论依据。以‘大西洋’、‘夏波蒂’、‘克新一号’和‘费乌瑞它’四个不同基因型马铃薯脱毒试管苗为试验材料,测定在不同蔗糖浓度下及经长期保存后恢复生长的马铃薯试管苗相关生理指标。结果表明:随着蔗糖处理浓度的增加,四个基因型马铃薯株高、有效节位数及腋芽萌发率均出现先增加后降低的生长趋势,当蔗糖浓度达到3%～4%时,除‘克新一号’外其余三个基因型均达到了最大值,6%的蔗糖浓度对‘大西洋’、‘夏波蒂’和‘费乌瑞它’的生长有明显的抑制作用;3%～6%的蔗糖浓度均能有效促进‘克新一号’的正常生长,8%的蔗糖浓度对其生长有显著的抑制作用;同时随着蔗糖浓度的增加均能有效延长四个基因型马铃薯试管苗的保存时间,当蔗糖浓度达到10%时,经保存一年均能达到90%以上的存活率,随着保存时间的延长其存活率又会有所下降。因此,3%的蔗糖浓度适合于‘大西洋’、‘夏波蒂’和‘费乌瑞它’基础苗扩繁,4%的蔗糖可作为三个基因型的壮苗培养基;4%的蔗糖浓度可同时作为‘克新一号’的扩繁和下地培养基;10%的蔗糖浓度可将四个基因型马铃薯脱毒试管苗的保存时间延长至1年,存活率均可达到90%以上,且长期保存后对试管苗继代生长无影响。本研究通过系统研究蔗糖对马铃薯试管苗生长和长期保存的影响,既有助于降低马铃薯试管苗工厂化生产成本,同时还可规避传统保存法造成的耗时耗工、种质资源易丢失等弊端,降低以植物生长抑制剂保存马铃薯种质造成的成活率低、变异率高等不安全因素。     

Growth and yield responses of spring wheat to increasing carbon dioxide, ozone and physiological stresses: a statistical analysis of ‘ESPACE-wheat’ results

One of the major goals of the European Stress Physiology and Climate Experiment (ESPACE-wheat) was to investigate the sensitivity of wheat growth and productivity to the combined effects of changes in CO₂ concentration, ozone and other physiological stresses. Experiments were performed at different sites throughout Europe, over three consecutive growing-seasons using open-top chambers. This paper summarizes the main experimental findings of the effects of CO₂ enrichment and other factors i.e. ozone (O₃), drought stress or nitrogen supply on the biomass and yield of spring wheat (Triticum aestivum cv. Minaret). Final harvest data from different sites and seasons were statistically analysed: (1) to identify main effects and interactions between experimentally controlled factors; and (2) to evaluate quantitative relationships between environmental variables and biological responses. Generally, ‘Minaret’ wheat did not respond significantly to O₃, suggesting that this cultivar is relatively tolerant to the O₃ levels applied. The main effect of CO₂ was a significant enhancement of grain yield and above-ground biomass in almost all experiments. Significant interactions between CO₂ and other factors were not common, although modifications in different N- and water supplies also led to significant effects on grain yield and biomass. In addition, climatic factors (in particular: mean air temperature and global radiation) were identified as important co-variables affecting grain yield or biomass, repectively. On average, the yield increase as a result of a doubling of [CO₂] was 35% compared with that observed at ambient CO₂ concentrations. However, linear regressions of grain yield or above-ground biomass for individual experiments revealed a large variability in the quantitative responses of ‘Minaret’ wheat to CO₂ enrichment (yield increase ranging from 11 to 121%). Hence, CO₂ responsiveness was shown to differ considerably when the same cultivar of wheat was grown at different European locations. Multiple regression analyses perfomed to evaluate the relative importance of the measured environmental parameters on grain yield indicated that although yield was significantly related to five independent variables (24 h mean CO₂ concentration, 12 h mean O₃ concentration, temperature, radiation, and drought stress), a large proportion of the observed variability remained unexplained.     

Photosynthetic and stomatal responses of potatoes grown under elevated CO2 and/or O3—results from the European CHIP-programme

The physiological effects of elevated CO₂ and/or O₃ on Solanum tuberosum cv. Bintje were examined in Open-Top Chambers during 1998 and 1999 at experimental sites across Europe as part of the EU ‘Changing Climate and Potential Impacts on Potato Yield and Quality’ programme (CHIP). At tuber initiation (≈20 days after emergence, DAE) elevated CO₂ (680 μl l⁻¹) induced a 40% increase in the light saturated photosynthetic rate (A_sat) of fully expanded leaves in the upper canopy. This was 16% less than expected from short-term exposures of plants grown under ambient CO₂ (360 μl l⁻¹) to elevated CO₂, indicating that photosynthetic acclimation began at an early stage of crop growth. This effect resulted from a combination of a 12% reduction in stomatal conductance (g_s) and a decline in photosynthetic capacity, as indicated by the significant reductions in the maximum carboxylation rate of Rubisco (Vc_max) and light-saturated rate of electron transport (J_max) under elevated CO₂. The seasonal decline in the promotion of photosynthesis by elevated CO₂ reflected the concurrent decrease in g_s. Vc_max and J_max were both reduced in plants grown under elevated CO₂ until shortly after maximum leaf area (MLA) was attained. Although non-photorespiratory mitochondrial respiration in the light (R_d) increased during the later stages of the season, net photosynthesis was consistently increased by elevated CO₂ during the main part of the season. Photosynthetic rate declined more rapidly in response to elevated O₃ under ambient CO₂, and the detrimental impact of O₃ was most obvious after MLA was attained (DAE 40–50). Several exposure indices were compared, with the objective of determining the critical ozone level required to induce physiological effects. The critical O₃ exposure above which a 5% reduction in light saturated photosynthetic rate may be expected (expressed in terms of cumulative exposure above 0 nl l⁻¹ O₃ between emergence and specific dates during the season (AOT0-cum)) was 11 μl l⁻¹ h; however this value should only be extrapolated beyond the CHIP dataset with caution. The interaction between O₃ and stomatal behaviour was more complex, as it was influenced by both long-term and daily exposure levels. Elevated CO₂ counteracted the adverse effect of O₃ on photosynthesis, perhaps because the observed reduction in stomatal conductance decreased O₃ fluxes into the leaves. The results are discussed in the context of nitrogen deficiency, carbohydrate accumulation and yield.     

Effects of elevated CO2 and cutting frequency on the productivity and herbage quality of a semi-natural grassland

Monoliths of a fertile, although N limited, C₃ grassland community were subjected (or not) to an atmospheric CO₂ enrichment (600 μmol mol⁻¹), owing to the Mini-FACE system from August 1998 to June 2001, at two contrasting cutting frequencies (3 and 6 cuts per year). The present study reports the effects of elevated CO₂ on the above-ground productivity and on the herbage quality. Elevated CO₂ did not affect the dry matter (DM) yield of the swards in 1999. In 2000, the second year, there was a positive CO₂ effect (+26%) both on the DM and on the nitrogen yields (+30%). With the frequently cut monoliths, the DM of the legume component of the sward was strongly increased by elevated CO₂. This effect became also significant in July 2000 for the low cutting frequency treatment. These results are in good agreement with the concept of an increased legume development and symbiotic N₂ fixation triggered by an increased ecosystem scale demand of N under elevated CO₂. At a low cutting frequency, the DM of the forbs was strongly increased in elevated compared with ambient CO₂. This increased development of the forbs apparently led to a competitive decline of the grasses. Therefore, the total DM yield response to CO₂ was smaller at a low (+15%) compared with a high (+36%) cutting frequency in 2000. An increase in the water soluble sugar content of the bulk forage under elevated CO₂ and a corresponding decline in cell wall contents (NDF) were observed. In June 1999, the decline in NDF was correlated with an increased in-vitro DM digestibility. The forage quality was also indirectly affected by elevated CO₂ through changes in leaf:stem ratio and in botanical composition. At a low cutting frequency, the increased forb content favoured the herbage quality because of a higher digestibility of the forb shoots and, indirectly, through the reduction in the mass of the grass stems. These results emphasise the role of species dynamics for elevated CO₂ impacts on semi-natural grassland productivity and herbage quality.     

不同氮效率粳稻生育后期产量形成的生理基础

为明确不同施氮量下高产粳稻在产量形成的关键时期光合生理特性的差异,在盆栽条件下,选取3个中粳（武育粳3号、南粳45、02102）和4个晚粳（武运粳7号、南粳44、南粳46、南粳5055）,在开花后不同天数,研究了不同施氮量下（150．0 kg/hm2：LN、300．0 kg/hm2：MN、450．0 kg/hm2：HN ）剑叶光合作用对光强和二氧化碳（CO2）响应曲线,氮代谢关键酶如硝酸还原酶（NR）、谷氨酰胺合成酶（GS）、谷氨酸合酶（GOGAT）谷氨酸脱氢酶（GDH）,抗氧化酶和非酶系统的抗氧化能力以及耐光氧化表现等,并在收获期考察其产量构成因子。结果表明：超级稻中粳南粳45和晚粳南粳44在LN、MN和HN的单株产量分别比对照武育粳3号和武运粳7号有所提高;随着施氮量的增加,水稻对高光强的利用能力增强,并可缓解开花后35 d剑叶的最大净光合速率（ Maximum net photosynthetic rate ,Pnmax ）的下降;而供试材料在LN或者MN下,在高CO2浓度下可通过提高表观羧化效率（ Apparent carboxylation efficiency ,ACE）,达到与HN的Pnmax ,提高CO2浓度有利于减氮;开花前期氮代谢相关酶活性诱导增加,后期超氧化物歧化酶（ Superoxide dismutase,SOD）的活性诱导增加以缓解后期光氧化,其中超级稻南粳44和南粳45在不同的氮素处理下,均具有中等耐光氧化和耐荫的特性。相关性分析表明,花后7 d的叶片的光合能力与千粒质量有关,而花后35 d,功能叶片的抗氧化能力则影响其结实率。可见,超级粳稻南粳44和南粳45在中等氮素下,可通过开花前期诱导NR和开花后期抗氧化能力增强,最大限度地发挥其叶片的光合功能,从而表现稳产高产。今后兼顾选择具有高光合特性的水稻品种,将是实现水稻高产和减氮统一的有效途径。