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1.
The present study investigated the effects of elevated carbon dioxide concentration ([CO2]) and air temperature on the germination of seed bulbils and the seedling vigour of two Chinese yam lines. Plants were grown under two [CO2] levels, ambient and elevated (ambient + 200 μmol mol?1), and two mean air temperature regimes, 22.2 °C (ambient + 1.4 °C) and 25.6 °C (ambient + 5.2 °C). Elevated [CO2] did not affect bulbil germination under both air temperature regimes. During the early growth stage, the dry weight (DW) of leaves, vines, shoots, roots, belowground parts (roots + tubers) and whole plants were higher under elevated [CO2] than ambient [CO2] for both lines under the low- and high-temperature regimes. The values of vigour indexes (index I = germination % × seedling length and index II = germination % × seedling DW) were also higher under elevated [CO2] than ambient [CO2] for both lines. These results indicated that Chinese yam seedlings respond positively to elevated [CO2] during the early growth stage. The above:belowground DW ratios were lower under elevated [CO2] than ambient [CO2] in seedlings with very small new tubers for both yam lines, indicating that elevated [CO2] strongly affected the root growth in the early growth stage. The DWs of post-treatment seed bulbils were higher in the elevated [CO2] under both air temperature regimes. The results showed that Chinese yam used a smaller amount of the reserves in seed bulbils under elevated [CO2] than under ambient [CO2].  相似文献   

2.
ABSTRACT

The effects of elevated carbon dioxide concentration on the morphology of leaf blades in two Chinese yam lines under different temperature conditions were determined. Plants were grown under two [CO2] levels, ambient (about 400 µmol mol?1) and elevated (ambient + 200 µmol mol?1) in the daytime, and two mean air temperature regimes, approximately ambient temperature (22.2°C) and high temperature (25.6°C). The palisade layer was thicker under elevated [CO2] than under ambient [CO2] in both temperature regimes, and the whole yam leaf blade was thicker under elevated [CO2] than under ambient [CO2] in the approximately ambient temperature regime. The numbers of chloroplasts per palisade cell and spongy cell as well as per unit profile area of palisade cell, number of starch grains per chloroplast, profile area of the starch grain, and starch-to-chloroplast area ratio in both palisade and spongy cells were higher under elevated [CO2] than under ambient [CO2] in both temperature regimes. Furthermore, the stomatal density on the abaxial side of the leaf blade in Chinese yam was greater under elevated [CO2] than under ambient [CO2] under both temperature regimes, and stomatal-pore length was higher under elevated [CO2] than under ambient [CO2] in the approximately ambient temperature regime. These results indicate that elevated [CO2] positively affects the photosynthetic apparatus. The results of this study provide information for understanding the response characteristics of the leaf blade under elevated [CO2] and a possible explanation for the positive photosynthetic responses of Chinese yam to elevated [CO2] in our previous study.

List of Abbreviations:[CO2]: carbon dioxide concentration  相似文献   

3.
《Plant Production Science》2013,16(3):307-315
Abstract

The effects of elevated carbon dioxide concentration ([CO2]) on silica deposition on husk epidermis of rice (Oryza sativa L. cv. Akitakomachi) during the flowering stage were investigated in this study. The study was motivated by the concept that the rice yield maybe affected by global warming as a result of elevated [CO2] environment since sterility of rice is related to the panicle silica content that influences transpiration, and elevated [CO2] could affect plant transpiration. Silica deposition analysis was focused on the flowering stage of the rice crop grown hydroponically under two [CO2] conditions: 350 μmol mol-1 (ambient) and 700 μmol mol-1 (elevated). Silica deposition on the husk epidermis from three parts of the panicle at four flowering stages were examined using a scanning electron microscope (SEM) combined with an energy dispersive X-ray microanalyzer (EDX). The results demonstrated that elevated [CO2] significantly suppressed silica deposition on the husk epidermis at the lower part of the panicle, and at the early flowering stage when 1/3 of the panicle emerged from the leaf sheath. In the transverse section analysis of the husk, silica deposition on the husk epidermis under elevated [CO2] was less than that under ambient [CO2] at the late flowering stage. The less silica deposition observed on the husks at the late flowering stage under elevated [CO2] might be related to the suppressed transpiration from the panicle by elevated [CO2] found in a previous study.  相似文献   

4.
《Plant Production Science》2013,16(2):156-167
Abstract

We tested the hypothesis that elevated CO2 concentration [CO2]-induced enhancement of biomass production of soybean is greater in a genotype that has a higher nitrogen (N) fixation capacity. Furthermore, we analyzed theinteractive effects of N fertilization, temperature and [CO2] on biomass production. Three genetically related genotypes: Enrei (normally-nodulating genotype), Kanto 100 (supernodulating genotype), and En1282 (non-nodulating genotype) were grown in pots, with or without N fertilizer for two years (2004, 2005). They were then subjected to two different [CO2] (ambient and elevated (ambient + 200 ?mol mol-1)) × two temperature regimes (low,high (low + 4~5ºC)). Top dry weight at maturity was the greatest in the elevated [CO2] × high temperature regime, irrespective of genotype and N fertilization. The [CO2] elevation generally enhanced N acquisition and dry matter production during the vegetative growth stage, and the enhancement was more pronounced in the nodulating genotypes (Enrei and Kanto 100) than in the non-nodulating genotype (En1282), indicating that N supply through N fixation contributes to elevated [CO2]-induced biomass production in soybean. However, the relative responsiveness ofbiomass production to elevated [CO2] was not necessarily higher in the supernodulating genotype than the normally-nodulating genotype. The N utilization efficiency to produce biomass was inferior in the supernodulating genotype than in the normally-nodulating and non-nodulating genotypes. These results did not fully verify the hypothesis that elevated [CO2]-induced enhancement of biomass production of soybean is greater in a genotype with a higher N fixation capacity.  相似文献   

5.
The present field experiment was conducted during two consecutive cropping seasons in central Portugal to study the effects of simultaneous elevation of carbon dioxide concentration ([CO2]) (550 μmol mol?1) and air temperature (+2–3 °C) on japonica rice (Oryza sativa L. “Ariete”) yield, crop duration, and SPAD-values across the seasons compared with the open-field condition. Open-top chambers were used in the field to assess the effect of elevated air temperature alone or the combined effect of elevated air temperature and atmospheric [CO2]. Open-field condition was assessed with randomized plots under ambient air temperature and actual atmospheric [CO2] (average 382 μmol mol?1). Results obtained showed that the rice “Ariete” had a moderate high yielding under open-field condition, but was susceptible to air temperature rise of +2–3 °C under controlled conditions resulting in reduction of grain yield. The combined increase of atmospheric [CO2] with elevated air temperature compensated for the negative effect of temperature rise alone and crop yield was higher than in the open-field. SPAD-readings at reproductive stage explained by more than 60 % variation the straw dry matter, but this finding requires further studies for consolidation. It can be concluded that potential increase in air temperature may limit rice yield in the near future under Mediterranean areas where climate change scenario poses a serious threat, but long term field experiments are required.  相似文献   

6.
Hybrid indica rice (Oryza sativa L.) cultivars play an important role in rice production system due to its heterosis, resistance to environmental stress, large panicle and high yield potential. However, no attention has been given to its yield responses to rising atmospheric [CO2] in conjunction with nitrogen (N) availability. Therefore we conducted a free air CO2 enrichment (FACE) experiment at Yangzhou, Jiangsu, China (119°42′0′′E, 32°35′5′′N), in 2004–2006. A three-line hybrid indica rice cv. Shanyou 63 was grown at ambient and elevated (ca. 570 μmol mol−1) [CO2] under two levels of supplemental N (12.5 g Nm−2 and 25 g Nm−2). Elevated [CO2] had no effect on phenology, but substantially enhanced grain yield (+34%). The magnitude of yield response to [CO2] was independent of N fertilization, but varied among different years. On average, elevated [CO2] increased the panicle number per square meter by 10%, due to an increase in maximum tiller number under enrich [CO2], while productive tiller ratio remained unaffected. Spikelet number per panicle also showed an average increase of 10% due to elevated [CO2], which was supported by increased plant height and stem dry weight per tiller. Meanwhile, elevated [CO2] caused a significant enhancement in both filled spikelet percentage (+5%) and individual grain weight (+4%). Compared with the two prior FACE studies on rice, hybrid indica rice cultivar appears to profit much more from elevated [CO2] than japonica rice cultivar (ca. +13%), not only due to its stronger sink generation, but also enhanced capacity to utilize the carbon sources in a high [CO2] environment. The above data has significant implication with respect to N strategies and cultivar selection under projected future [CO2] levels.  相似文献   

7.
《Plant Production Science》2013,16(3):238-245
Abstract

Waterlogging is a major predicted agricultural problem for crop production in some areas under current climate change, but no studies are available on the interactive effects of waterlogging and elevated atmospheric CO2 concentration ([CO2]). We hypothesized that elevated [CO2] could alleviate the damage caused by waterlogging, and tested the hypothesis using vegetative growth of soybean (Glycine max) in 10 experiments (different sowing time and different soil type) conducted at Morioka and Tsukuba for three years. The 2-week-old plants grown under elevated and ambient [CO2] were exposed to waterlogging for 2 weeks. Total dry weight at the end of the treatment was higher under elevated [CO2] than under ambient [CO2], and it was significantly reduced by waterlogging under both levels of [CO2], without significant [CO2]×waterlogging interactions, at both locations. The negative effects of the waterlogging were greater in root dry weight than in top dry weight, and the root exudation per unit root dry weight was also reduced by waterlogging, without a [CO2] ×waterlogging interaction. Therefore, the hypothesis of a [CO2]×waterlogging interaction can be rejected, and provide an important basis for predicting future damage caused by waterlogging under elevated [CO2] conditions.  相似文献   

8.
Because CO2 is needed for plant photosynthesis, the increase in atmospheric CO2 concentration ([CO2]) has the potential to enhance the growth and yield of rice (Oryza sativa L.), but little is known regarding the impact of elevated [CO2] on grain quality of rice, especially under different N availability. In order to investigate the interactive effects of [CO2] and N supply on rice quality, we conducted a free-air CO2 enrichment (FACE) experiment at Wuxi, Jiangsu, China, in 2001–2003. A long-duration rice japonica with large panicle (cv. Wuxiangging 14) was grown at ambient or elevated (ca. 200 μmol mol−1 above ambient) [CO2] under three levels of N: low (LN, 15 g N m2), medium (MN, 25 g N m2) and high N (HN, 35 g N m2 (2002, 2003)). The MN level was similar to that recommended to local farmers. FACE significant increased rough (+12.8%), brown (+13.2%) and milled rice yield (+10.7%), while markedly reducing head rice yield (−13.3%); FACE caused serious deterioration of processing suitability (milled rice percentage −2.0%; head rice percentage −23.5%) and appearance quality (chalky grain percentage +16.9%; chalkiness degree +28.3%) drastically; the nutritive value of grains was also negatively influenced by FACE due to a reduction in protein (−6.0%) and Cu content (−20.0%) in milled rice. By contrast, FACE resulted in better eating/cooking quality (amylose content −3.8%; peak viscosity +4.5%, breakdown +2.9%, setback −27.5%). These changes in grain quality revealed that hardness of grain decreased with elevated [CO2] while cohesiveness and resilience increased when cooked. Overall, N supply had significant influence on rice yield with maximum value occurring at MN, whereas grain quality was less responsive to the N supply, showing trends of better appearance and eating/cooking quality for LN or MN-crops as compared with HN-crops. For most cases, no [CO2] × N interaction was detected for yield and quality parameters. These data suggested that the current recommended rates of N fertilization for rice production should not be modified under projected future [CO2] levels, at least for the similar conditions of this experiment.  相似文献   

9.
The objective of this study was to identify physiological processes that result in genotypic and N fertilization effects on rice yield response to elevated atmospheric CO2 concentrations ([CO2]). This study conducted growth and yield simulations for 9 rice genotypes grown at 4 climatically different sites in Asia, assuming the current atmospheric [CO2] (360 ppm) and elevated [CO2] (700 ppm) using 5 levels of N fertilizer (4, 8, 12, 16, 20 g m−2 N fertilizer). A rice growth model that was developed and already validated for 9 different genotypes grown under 7 sites in Asia was used for the simulation, integrating additional components into the model to explain the direct effect of [CO2] on several physiological processes. The model predicted that the relative yield response to elevated [CO2] (RY, the ratio of yield under 700 ppm [CO2] to that under 360 ppm [CO2]) increased with increasing N fertilizer, ranging from 1.12 at 4 g m−2 N fertilizer to 1.22 at 20 g m−2 N fertilizer, averaged overall genotypes and locations. The model also predicted a large genotypic variation in RY at the 20 g N treatment, ranging from 1.08 for ‘WAB450-I-B-P-38-HB’ to 1.41 for ‘Takanari’ averaged overall locations. Combining all genotypes grown at the 5N fertilization conditions, a close 1:1 relationship was predicted between RY and the relative [CO2] response in spikelet number for crops with a small number of spikelets (less than 30,000 m−2) under the current atmospheric [CO2] (n = 18, r = 0.89***). In contrast, crops with a large number of spikelets under the current atmospheric [CO2] showed a significantly larger RY than the relative [CO2] response for spikelet number per unit area. The model predicted that crops with a larger number of spikelets under the current atmospheric [CO2] derived great benefit from elevated [CO2] by directly allocating increased carbohydrate to their large, vacant sink, whereas crops with a smaller number of spikelets primarily required an increased spikelet number to use the increased carbohydrate to fill grains. The simulation analyses suggested that rice with a larger sink capacity relative to source availability under the current atmospheric [CO2] showed a larger yield response to elevated [CO2], irrespective of whether genotype or N availability was the major factor for the large sink capacity under the current [CO2]. The model predicted that the RY response to nitrogen was brought about through the N effects on spikelet number and non-structural carbohydrate accumulation. The genotypic variation in RY was related to differences in spikelet differentiation efficiency per unit plant N content. Further model validation about the effects of [CO2] on growth processes is required to confirm these findings considering data from experimental studies.  相似文献   

10.
《Journal of Crop Improvement》2013,27(1-2):377-392
SUMMARY

Two poplar clones, hybrid Populus deltoides Bartr. Ex Marsh X Populus nigra L. (Populus xeuramericana), clone I-214, and Populus deltoides, clone Lux, were grown from hardwood cuttings for one growing season in either ambient (360 μmol mol?1) or elevated (560 μmol mol?1) [CO2] in FACE-systemrings at Rapolano Terme (Siena, Italy). Both clones I-214 and Lux exhibited a higher aboveground bio-mass, photosynthesis at light saturation and instantaneous transpiration efficiency (ITE) in CO2-enriched air. The elevated [CO2]-induced responses of clone I-214 included increased investment in branch and leaf biomass, and enhanced stem volume. The elevated [CO2]-induced responses of clone Lux included an increase in the number of branches (and foliage area). Indication of photosynthetic acclimation under elevated [CO2] was found during the early morning, but only in clone I-214. Stomatal conductance decreased under elevated [CO2] particularly in clone Lux. Clone differences in response to elevated [CO2] should be taken in account when planning future poplar plantations in forecast warmer and drier Mediterranean sites.  相似文献   

11.
Hybrid rice cultivar plays an important role in rice production system due to its high yield potential and resistance to environmental stress. Quantification of its responses to rising CO2 concentration ([CO2]) will reduce our uncertainty in predicting future food security and assist in development of adaptation strategies. Using free air CO2 enrichment (FACE), we measured seasonal changes in growth and nitrogen (N) uptake of an inter-subspecific hybrid rice cultivar Liangyoupeijiu grown under two levels of [CO2] (ambient and elevated by 200 μmol mol−1) and two levels of N fertilization in 2005–2006. Average across the 2 years, FACE increased crop growth rate similarly by 22%, 24% and 23% in the periods from transplanting to panicle initiation (PI), PI to heading and heading to maturity, which was mainly attributed to an increase in green leaf area index rather than the greater net assimilation rate. Grain yield increased greatly under FACE as a result of similar contributions by panicle number per unit area, grain number per panicle and individual grain yield. Final aboveground N acquisition showed a 10.4% increase under FACE, which resulted from enhanced N uptake at both vegetative and reproductive growth stages. Compared with previous FACE studies on final productivity of two inbred japonica cultivars, inter-subspecific hybrid cultivar appears to profit more from elevated [CO2], which mainly resulted from its greater enhancement in photosynthetic production during reproductive growth due to a lack of N limitations late in the season.  相似文献   

12.
Over time, the relative effect of elevated [CO2] on the photosynthesis and dry matter (DM) production of rice crops is likely to be changed with increasing duration of CO2 exposure. However, there is no systemic information on interactive effects of elevated [CO2] and nitrogen (N) supply on seasonal changes in phosphorus (P) nutrient of rice crops. In order to investigate the interactive effects of these two factors on seasonal changes in plant P concentration, uptake, efficiency and allocation, a free-air CO2 enrichment (FACE) experiment was conducted at Wuxi, Jiangsu, China, in 2001–2003. A japonica cultivar with large panicle was grown at ambient or elevated (ca. 200 μmol mol−1 above ambient) [CO2] and supplied with three levels of N: low (LN, 15 g N m2), medium (MN, 25 g N m2) and high N (HN, 35 g N m2 (2002, 2003)). The MN level was similar to that recommended to local farmers. FACE significantly increased shoot P concentration (dry base) over the season, the average responses varied between 7.3% and 16.2%. Shoot P uptake responses to FACE declined gradually with crop development, with average responses of 57%, 51%, 37%, 26% and 11% on average during the growth periods from transplanting to early-tillering (Period I), early-tillering to mid-tillering (Period II), mid-tillering to panicle initiation (Period III), panicle initiation to heading (Period IV) and heading to grain maturity (Period V), respectively. Seasonal changes in shoot P uptake ratio (i.e., the ratio of shoot P uptake during a given growth period to final shoot P acquisition at grain maturity) responses to FACE followed a similar pattern to that of shoot P uptake, with average responses of 19%, 14%, 3%, −5% and −16% in Periods I, II, III, IV and V of the growth period, respectively. As a result, FACE enhanced shoot P uptake by 33% at grain maturity. P allocation patterns among above-ground organs were not altered by FACE before heading, but it was modified after heading, with a shift in P allocation patterns towards vegetative organ. FACE resulted in the significant decrease in P-use efficiency for biomass across the season and P-use efficiency for grain yield and P harvest index at grain maturity. Generally, there were no interactions between [CO2] and N supply on above P nutrient variables measured. Data from this study has important implications for P management in rice production systems under future elevated [CO2] conditions.  相似文献   

13.

Background

Heat-tolerant rice cultivars have been developed as a countermeasure to poor grain appearance quality under high temperatures. Recent studies showed that elevated CO2 concentrations (E-[CO2]) also reduce grain quality. To determine whether heat-tolerant cultivars also tolerate E-[CO2], we conducted a free-air CO2 enrichment (FACE) experiment with 12 rice cultivars differing in heat tolerance.

Results

The percentage of undamaged grains of five standard cultivars (Akitakomachi, Kinuhikari, Koshihikari, Matsuribare, Nipponbare) averaged 61.7% in the ambient [CO2] (AMB) plot and 51.7% in the FACE plot, whereas that of heat-tolerant cultivars (Eminokizuna, Wa2398, Kanto 257, Toyama 80, Mineharuka, Kanto 259, Saikai 290) averaged 73.5% in AMB and 71.3% in FACE. This resulted in a significant [CO2] by cultivar interaction. The percentage of white-base or white-back grains increased from 8.4% in AMB to 17.1% in FACE in the sensitive cultivars, but from only 2.1% in AMB to only 4.4% in FACE in the heat-tolerant cultivars.

Conclusion

Heat-tolerant cultivars retained their grain appearance quality at E-[CO2] under present air temperatures. Further improvements in appearance quality under present conditions will be needed to achieve improvements under E-[CO2], because E-[CO2] will likely lower the threshold temperature for heat stress.  相似文献   

14.
《Field Crops Research》2006,98(1):12-19
It is reported that stimulating effect of elevated atmospheric [CO2] on photosynthesis of rice (Oryza sativa L.) is likely to be reduced during the plant growth period. However, there is little information on seasonal changes in dry matter (DM) production and distribution of rice under elevated atmospheric [CO2]. A free-air CO2 enrichment (FACE) experiment was conducted at Wuxi, Jiangsu, China, in 2001–2003, using Wuxiangging 14, a japonica cultivar. The rice was grown at ambient or elevated (ca. 200 μmol mol−1 above ambient) [CO2] and supplied with 25 g N m2, which is the normal N application rate for local farmers. DM accumulation of rice in FACE plots was significantly increased by 40, 30, 22, 26 and 16% on average at tillering, panicle initiation (PI), heading, mid-ripening and grain maturity, respectively. Rice DM production under FACE was significantly enhanced by 41, 27, 15 and 38% on average during the growth periods from transplanting to tillering (Period 1), tillering to PI (Period 2), PI to heading (Period 3) and heading to mid-ripening (Period 4), respectively, but significantly decreased by 25% in the period from mid-ripening to grain maturity (Period 5). In general, seasonal changes in crop response to FACE in both green leaf area index (GLAI) and net assimilation rate (NAR) followed a similar pattern to that of the DM production. Under FACE the leaves decreased significantly in proportion to the total above-ground DM over the season, the stems showed an opposite trend, while the spikes depended on crop development stage: showing no change at heading, significant increase (+4%) at mid-ripening and significant decrease (−3%) at grain maturity. Grain yield was stimulated by an average of 13% by FACE, due to increased total DM production rather than any changes in partitioning to the grain. We conclude that the gradual acclimation of rice growth to elevated [CO2] do not occur inevitably, and it could also be altered by environmental conditions (e.g., cultivation technique).  相似文献   

15.
The increase in atmospheric CO2 concentration [CO2] has been demonstrated to stimulate growth of C3 crops. Although barley is one of the important cereals of the world, little information exists about the effect of elevated [CO2] on grain yield of this crop, and realistic data from field experiments are lacking. Therefore, winter barley was grown within a crop rotation over two rotation cycles (2000 and 2003) at present and elevated [CO2](375 ppm and 550 ppm) and at two levels of nitrogen supply (adequate (N2): 262 kg ha−1 in 1st year and 179 kg ha−1 in 2nd year) and 50% of adequate (N1)). The experiments were carried out in a free air CO2 enrichment (FACE) system in Braunschweig, Germany. The reduction in nitrogen supply decreased seasonal radiation absorption of the green canopy under ambient [CO2] by 23%, while CO2 enrichment had a positive effect under low nitrogen (+8%). Radiation use efficiency was increased by CO2 elevation under both N levels (+12%). The CO2 effect on final above ground biomass was similar for both nitrogen treatments (N1: +16%; N2: +13%). CO2 enrichment did not affect leaf biomass, but increased ear and stem biomass. In addition, final stem dry weight was higher under low (+27%) than under high nitrogen (+13%). Similar findings were obtained for the amount of stem reserves available during grain filling. Relative CO2 response of grain yield was independent of nitrogen supply (N1: +13%; N2: +12%). The positive CO2 effect on grain yield was primarily due to a higher grain number, while changes of individual grain weight were small. This corresponds to the findings that under low nitrogen grain growth was unaffected by CO2 and that under adequate nitrogen the positive effect on grain filling rate was counterbalanced by shortening of grain filling duration.  相似文献   

16.
There have been no studies conducted with the objective of investigating the effect of elevated CO2 concentrations ([CO2]) on antioxidants in grains. Therefore, a two-year field experiment was conducted using open-top chambers with two levels of atmospheric CO2 (375 and 550 μmol/mol) to evaluate their effects on rice grain antioxidants. Following exposure to high [CO2], the total phenolic content of all rice milling fractions decreased (3%–18%), with the highest reduction in the brown rice for sinapic acid (167%), and in the white rice for p-hydroxybenzoic acid (100%). The total flavonoid content also decreased under elevated [CO2] in all rice milling fractions (8%–14%), with apigenin (25%) being highly affected in the white rice, and tricin (12%) in the bran. The same trend was found for γ-oryzanol, with decreases of 35%, 32%, 25%, and 2% in the white rice, brown rice, husk, and bran, respectively. In the white and brown rices, tocopherols and tocotrienols were all lower under elevated [CO2], with reductions larger for α-tocotrienol (69%), γ-tocotrienol (46%), and α-tocopherol (38%). Good correlations between antioxidant contents and DPPH radical scavenging capacities indicated that these decreases may be meaningful in the preventive ability of rice against free radical-mediated degenerative diseases.  相似文献   

17.
《Field Crops Research》1995,41(1):13-23
The objectives of this study were to evaluate effects of ambient and double ambient [CO2] at a range of growing temperatures on photosynthesis, respiration, transpiration, water-use efficiency and dry matter accumulation of cotton plants (Gossypium hirsutum L., cv. DPL 50). In Experiment I, plants were grown outdoors until first bloom, then transferred into naturally lit growth chambers and grown for 22 days at 30/18°C with five CO2 concentrations varying from 350 to 900 μl l−1. In Experiment II, air temperatures were maintained at 20/12, 25/17, 30/22, and 35/27°C day/night during a 70-day experimental period with [CO2] of 350 and 700 μl l−1 at each temperature. Photosynthesis increased with [CO2] from 350 to 700 μl l−1 and with temperature. Plants grown at 35/27°C produced fewer bolls due to abscission compared with plants grown at optimum temperatures (30/20°C). At higher [CO2], water-use efficiency increased at all temperatures due mainly to increased canopy photosynthesis but also to more limited extent to reduced canopy transpiration. Increased photosynthesis at higher [CO2] resulted in greater dry matter accumulation at all temperatures except at 20/12°C. Respiration increased as dry matter and temperature increased. Plants grown at higher [CO2] had less respiration per unit dry matter but more per unit area. These results indicate that future increases in [CO2] are likely to benefit cotton production by increasing carbon assimilation under temperatures favorable for cotton growth. Reduced fruit weights at higher temperatures indicate potential negative effects on production if air temperatures increase as projected in a high-CO2 world.  相似文献   

18.
The impact of rising carbon dioxide concentration ([CO2]) in the atmosphere on wheat grain protein concentration and proteome was investigated in this study. Wheat genotypes (H45, SB003, SB062 and Yitpi) were grown in the Australian Grains Free-Air CO2 Enrichment (AGFACE) facility, Horsham, Victoria, Australia under ambient [CO2] (a[CO2], 391 μmol mol−1) and elevated [CO2] (e[CO2], 550 ± 20 μmol mol−1). Grain yield and grain protein concentration were measured. Global grain proteome comparison was carried out using stable isotope dimethyl labelling followed by liquid chromatography - mass spectrometry (LC-MS/MS). Grain yield was significantly increased at e[CO2], whereas protein concentration was significantly decreased and responses varied between genotypes. Proteome-wide analysis revealed that protein composition was also altered under e[CO2]. Grain protein concentration and composition of SB003 was very responsive to e[CO2]. Mainly storage proteins were decreased at e[CO2] and the responses varied between genotypes. These findings suggest that e[CO2] may have a major impact on grain protein quality and thus bread quality and human and animal nutrition. Further, these findings suggest that [CO2] insensitive cultivars can be identified for grain quality improvement under changing climate.  相似文献   

19.
A field study was carried out to quantify the compensation capacity of Bacillus thuringiensis (Bt)-transgenic cotton to simulated damage by manually removing squares during the early growing season in 2004 and 2005 in combination with CO2 levels (ambient CO2 and elevated CO2). Treatments included: initial squares were wholly (100%) removed manually for 1 week (i.e., SR1 treatment) and for 2 consecutive weeks (i.e., SR2 treatment). Plant leaf area was measured every 2 weeks, and plant root, stem, leaf, shatters, boll dry weight and lint yield and maturity were measured at harvest. Significantly higher leaf area per plant was observed on each sampling date for SR1 and SR2 treatments compared with control (SR0) treatment in 2004 and 2005 under elevated CO2. Significantly higher lint yield and maturity were observed for SR0, SR1 and SR2 treatments under elevated CO2 in 2004 and 2005. CO2 concentration and square removal significantly affected plant lint yield and maturity. Moreover, the interaction between CO2 concentration × square removal had a significant effect on plant leaf dry weight, lint yield and maturity. Our results indicated that transgenic cotton plants can compensate for the manual removal of 100% of the initial squares for 1 and 2 weeks under ambient and elevated CO2.  相似文献   

20.
《Field Crops Research》2003,82(1):37-47
High leaf to air water vapor pressure differences often substantially reduce rates of assimilation of carbon dioxide, especially in C3 species. Rising concentrations of carbon dioxide [CO2] in the atmosphere could reduce the sensitivity of assimilation rate to partial stomatal closure caused by high vapor pressure difference by a variety of mechanisms. However, field data addressing this question are scarce. In this study, we examined day-to-day variation in midday gas exchange rates of upper canopy leaves of potato and sorghum grown at the current ambient [CO2] and ambient+350 μmol mol−1 [CO2] in field plots. Stomatal conductance and assimilation rate were negatively correlated with vapor pressure difference across days. Assimilation rate was not less sensitive to vapor pressure difference at elevated than at ambient [CO2] in either species. For both potato and sorghum short-term increases in vapor pressure difference for individual leaves produced significantly smaller responses of leaf gas exchange than did the day-to-day variation in vapor pressure difference, again with no reduced sensitivity at elevated [CO2]. The smaller response of gas exchange to short-term manipulations of vapor pressure difference than to day-to-day variation may indicate that much of the response to high vapor pressure difference apparent in the day-to-day variation resulted from leaf water deficits caused by exposure of the whole canopy to high vapor pressure difference, rather than from direct effects of high water vapor pressure difference. The lack of a [CO2] effect on the sensitivity of assimilation rate to vapor pressure difference, and the substantial sensitivity of assimilation rate to vapor pressure difference in the C4 species both resulted from reductions in assimilation at a given internal [CO2] at high vapor pressure difference. An implication of these results is that that high leaf to air water vapor pressure difference may continue to be a major limitation to assimilation rates in C3 and C4 crop species even at twice the current concentration of carbon dioxide in the atmosphere.  相似文献   

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