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1.
Dry Matter Production, CO2 Exchange, Carbohydrate and Nitrogen Content of Winter Wheat at Elevated CO2 Concentration and Drought Stress
Methods of mathematical modelling and simulation are being used to an increasing degree in estimating the effects of rising atmospheric CO2 concentration and changing climatic conditions on agricultural ecosystems. In this context, detailed knowledge is required about the possible effects on crop growth and physiological processes. To this aim, the influence of an elevated CO2 concentration and of drought stress on dry matter production, CO2 exchange, and on carbohydrate and nitrogen content was studied in two winter wheat varieties from shooting to milk ripeness. Elevated CO2 concentration leads to a compensation of drought stress and at optimal water supply to an increase of vegetative dry matter and of yield to the fourfold value. This effects were caused by enhanced growth of secondary tillers which were reduced in plants cultivated at atmospheric CO2 concentration. Analogous effects in the development of ear organs were influenced additionally by competitive interactions between the developing organs. The content and the mass of ethanol soluble carbohydrates in leaves and stems were increased after the CO2 treatment and exhausted more completely during the grain filling period after drought stress. Plants cultivated from shooting to milk ripeness at elevated CO2 concentration showed a reduced response of net photosynthesis rate to increasing CO2 concentration by comparison with untreated plants. The rate of dark respiration was increased in this plants.  相似文献   

2.
A study of the characterization of CO2 responsiveness in Brassica oxycamp and its parents Brassica oxyrrhina and Brassica campestris was done using open top chamber technology. The response of the X. B. oxycamp (hybrid) to elevated CO2 was significantly positive in respect of photosynthesis and growth and similar to that of its parent B. campestris. X B. oxycamp and B. campestris with greater sink potential responded significantly, whereas B. oxyrrhina with a poor sink, did not respond to CO2 enrichment. Photosynthetic changes at elevated CO3 levels in the hybrid and parents are partially attributed to the CO2 effects on stomatal conductance and chlorophyll fluorescence.  相似文献   

3.
The response of Brassica juncea var. Bio-183-92 to elevated CO2 under increased nitrogen treatment was studied. There was an interactive effect of CO2 and nitrogen nutrition, indicating that, on the addition of more nitrogen, the plants sustained the positive effect of CO2 enrichment by utilizing additional carbohydrates for the development of new sinks. Excess carbohydrate enables plants to be flexible and responsive to additional nitrogen application to sustain the CO2 enrichment effect.  相似文献   

4.
A versatile method was developed for the application of 1000 ppm CO2 during the whole growth period of plants. Temperature controlled water cooling and ventilation of the greenhouse resulted in a monthly CO2 enrichment time of 60 to 90 % of the total light period. Digitalis lanata , grown in greenhouses with CO2 enrichment during the whole growth phase from April to November, produced twice as much biomass as field cultivated plants.
The relative yield of the glycoside digoxin per gram Digitalis drug dry weight was 0.4% in field grown and 0.7% in greenhouse cultivated plants. The production of digoxin per hectare in the greenhouse at 1000 ppm CO2 was almost 3.5-fold that by field cultivation. Drug yield and secondary metabolite production in D. lanata were remarkably influenced by increased temperature and elevated CO2 partial pressure in the greenhouse.  相似文献   

5.
The effect of secondary salinization on photosynthesis was studied in fodder oat genotypes Kent, JHO-829, JHO-881, UPO-94 and OS-6 at the flower initiation stage. With an increase in the electrical conductivity (EC) of irrigation water, the net photosynthesis rate (PN) and the transpiration rate (E) of all the genotypes decreased. The intercellular CO2 concentration (Ci) increased in all genotypes at 10 dS m−1. Stomatal resistance (Rs) had a strong negative correlation with PN and E. The increase in Ci together with the increase in the Rs shows that at higher EC non-stomatal factors also start contributing to the limitation of photosynthesis. This study suggests that secondary salinization effects are strongly under stomatal control at lower saline water irrigation levels, but at higher levels non-stomatal factors may come into play.  相似文献   

6.
Winter rape (cv.'Falcon') grown under different nitrogen regimes (N0, N120; 0 and 120 kg.ha−1, respectively) in northern Germany was investigated over the 1996 spring–summer season. Using a CO2, H2O diffusion porometer, diurnal courses or net photosynthesis and respiration were measured in situ and were related to microclimatic conditions and leaf water relations. Photosynthesis was modelled and daily CO2 gain was calculated. In contrast to the N120 plants, plants of the low nitrogen plot (N0) grew less densely and their leaves behaved more like sun leaves. Increased nitrogen supply had little influence on photosynthetic capacity but it increased productivity through higher leaf area index and an extended period of photosynthetic activity. N120 plants also appeared to be better acclimated to hot, summer conditions. Higher nitrogen supply substantially increased seed production with the yield of the N120 plants being 16% of the N0 plants.  相似文献   

7.
The rhizosphere is the site of organic deposition and the generator of habitat and resource heterogeneity for soil organisms. Plants can modify their rhizosphere through nutrient, moisture and O2 uptake from the rhizosphere, rhizo-deposition and production of root exudates. As a result, rhizosphere chemical (pH, nutrient solubility, O2, CO2 and other chemicals), physical (moisture and aeration), and biological (soil pathogens, beneficial microorganisms and allelopathy) characteristics will be changed or modified. Rhizosphere microorganisms have positive or negative effects on plant growth and morphology by affecting the plant hormone balance, plant enzymatic activity, nutrient availability and toxicity, and competition with other plants. Plants modify the rhizosphere and as a result will modify the community.  相似文献   

8.
An attempt has been made to study the interactive effect of elevated CO2 and moisture stress on photosynthesis, growth and water relations of Brassica species using open top chambers. It was observed that plants responded to elevated CO2 significantly under moisture stress condition mitigating the adverse effects on photosynthesis and growth of Brassica species. Relatively drought susceptible species, viz. B. campestris and B. nigra , responded to elevated CC2 markedly as compared to less sensitive B. carinata and B. juncea plants. The water status of plants significantly improved under elevated CO2 concentration possibly by increasing stomatal resistance and/or by increased root growth.  相似文献   

9.
Pflanzenwachstum durch CO2/HCO3-Eintrag über die Wurzel   总被引：1，自引：0，他引：1  
Plant Growth after Application of CO2/HCO3 to the Roots
After applying H14CO3 to the root system of summer wheat in hermetically sealed pots, absorption and incorporation of HCO3 in the sugar-, starch-, and fibre-fraction (approximately 50 % of the absorped 14C) could be shown. This fraction reached 0.44–1.21 % of total C-assimilation of the shoot during growing stage F9/F10 on the Feeke-scala. 1/3 of the HCO3-fraction resting in the soil was bound organically indicating that microorganisms may be able to utilize exogenous anorganic CO2/HCO3 for their photosynthesis.  相似文献   

10.
Understanding the influence of growth temperature and carbon dioxide (CO2) on seed quality in terms of seed composition, subsequent seedling emergence and early seedling vigour is important under present and future climates. The objective of this study was to determine the combined effects of elevated temperature and CO2 during seed-filling of parent plants on seed composition, subsequent seedling emergence and seedling vigour of red kidney bean ( Phaseolus vulgaris ). Plants of cultivar 'Montcalm', were grown at daytime maximum/nighttime minimum sinusoidal temperature regimes of 28/18 and 34/24 °C at ambient CO2 (350 μmol mol−1) and at elevated CO2 (700 μmol mol−1) from emergence to maturity. Seed size and seed composition at maturity and subsequent per cent emergence, early seedling vigour (rate of development) and seedling dry matter production were measured. Elevated CO2 did not influence seed composition, emergence, or seedling vigour of seeds produced either at 28/18 or 34/24 °C. Seed produced at 34/24 °C had smaller seed size, decreased glucose concentration, but significantly increased concentrations of sucrose and raffinose compared to 28/18 °C. Elevated growth temperatures during seed production decreased the subsequent per cent emergence and seedling vigour of the seeds and seedling dry matter production of seed produced either at ambient or elevated CO2.  相似文献   

11.
A field experiment was conducted to find out the critical physiological stages of irrigation schedules inducing better growth, physiological efficiency and seed yield potential of berseem ( Trifolium alexandrinum L., Var. S-99-1). For this purpose eight irrigation treatments were made comprised of four treatments of three irrigation (W1, W2, W3 and W4), three treatments of four irrigation (W5, W7 and W8) and one treatment of five irrigation (W6) at various physiological stages i. e. regeneration, flower initiation, full bloom, seed initiation and advance seed development stage.
Thus based on the experimental results the physiological role of watering in berseem seed production could be discussed as:
With-holding of irrigation either at regeneration or at full bloom stage developed potential water stress in plants as indicated by high proline content of irrigation treatments — W4, W1 and W7; and further brought out disturbance on the formation of carotene, synthesis of water soluble sugar and translocation of sugar towards reproductive organs during grain development stage. These stresses adversely affected the plant growth and flowering behaviour. The irrigation at seed initiation stage increased the seed yield. Continuous irrigation did not appear to be useful. Thus it can be concluded that irrigation at three critical physiological stages i. e. regeneration, full bloom and seed initiation was found to be essential for obtaining potential seed yield of berseem.  相似文献   

12.
The heterosis of leaf photosynthesis was studied on the main characters included in the range from CO2exchange rate (CER) to enzymatic activity using a remote cross F, rice. The CER was significantly higher than those of the parental strains, showing a 111 % heterosis effect on average; at the same time strong heterosis was observed for the leaf area production and growth. Also stomatal and mesophyll conductances increased in the F1 rice, which may contribute to the increase in CER. Chlorophyll content (Ch1), soluble protein content (SPC) and ribulose 1,5-bisphosphate (RuBP) carboxylase activity (RCA) were measured as the internal factors related to photosynthesis, and compared between the F1, rice and the parents. For all these factors, the F1 rice showed low values compared to the parents. Positive heterosis was not expressed here. On the other hand, the specific activity of RCA (RCA/SPC) increased in the F1, rice, showing a 120% heterosis effect. This may be regarded as one of the main causes for the increase in CER of the F1, rice. High CER expressed as heterosis concurrently with large leaf area production is one of the important findings in our study, and this may suggest a high possibility of further improvement in biomass production or yield of rice by gathering the advantageous elements into a hybrid plant.  相似文献   

13.
The effect of plant water stress on net photosynthesis and leaf growth were investigated in order to determine to what extent leaf water potential during vegetative growth and silking affects maize development.
Two commercial maize hybrids grown in pots in a glasshouse were subjected to leaf water potentials of -1300 and -1700 kPa during the eighth leaf stage and during silking to -1700 and -2300 kPa to previously unstressed, moderately and severely stressed plants. The effect of stress on inhibiting CO2 uptake rates and leaf areas, as well as the recovery after alleviating stress, were compared to that of unstressed plants.
No substantial differences in CO2 uptake rates were found between medium and long seasoned cultivars. The CO2 uptake rates per unit leaf area decreased to negative values under both moderate and severe stress conditions during both growth stages. During silking, the recovery of CO2 uptake rate was much lower than during the eight leaf stage. Leaf area decreased proportionally with increased stress but did not recover after alleviating stress on plants stressed during both the eighth leaf and silking stages.  相似文献   

14.
This study investigated whether the exogenous application of glycine betaine (GB) could alleviate the adverse effects of water deficit on sunflower. Two sunflower lines, Gulshan-98 and Suncross, were subjected to water deficit at the vegetative or the reproductive stages of plant growth. Three levels (0, 50 and 100 mmol l−1) of GB were applied as a pre-sowing seed treatment or as a foliar spray at the time of initiation of water deficit at the vegetative or reproductive stages. Foliar application of GB at the time of initiation of water deficit treatments showed a marginal increase in shoot biomass in drought-stressed plants. Exogenously supplied GB as a foliar spray also showed a positive role in reducing the effects of water deficit on net CO2 assimilation rate, transpiration rate and sub-stomatal CO2 concentration in both sunflower lines. Pre-sowing seed treatment with GB had no effects on the above-mentioned physiological and growth attributes in both normally irrigated and drought-stressed plants. Taken together, foliar application of GB increased net CO2 assimilation rate which in turn showed a slight increase in growth of water-stressed plants but this increase was not related to stomatal regulation.  相似文献   

15.
Drought stress is the most pervasive threat to sustainable rice production and mainly disrupts membrane structure and cell-water relations. Exogenously applied brassinosteroids (BRs) may produce profound changes that may improve drought tolerance in rice. In this study, we monitored some physiological basis of the exogenously applied BRs in improving drought tolerance in fine grain aromatic rice ( Oryza sativa L.). Two BRs i.e. 28-homobrassinolide (HBL) and 24-epibrassinolide (EBL) were used both as seed priming and foliar spray. To prime, the seeds were soaked in 0.01 μ m aerated solution each of HBL and EBL for 48 h and dried back to original weight. Treated and untreated seeds were sown in plastic pots with normal irrigation in a phytotron. At four-leaf stage (3 weeks after sowing), plants were subjected to drought stress at 50 % field capacity by cutting down the water supply. For foliar spray, 0.01 μ m of HBL and EBL solutions were sprayed at five-leaf stage. Drought stress severely reduced fresh and dry weights, whilst exogenously applied BRs improved net CO2 assimilation, water use efficiency, leaf water status, membrane properties, production of free proline, anthocyanins, soluble phenolics, but declined the malondialdehyde and H2O2 production. In conclusion, BRs application improved the leaf water economy and CO2 assimilation, and enabled rice to withstand drought. Moreover, foliar spray had better effect under drought than seed treatments and of the two BRs, EBL proved more effective.  相似文献   

16.
Field bean planes cultivar Nadwiślański were submitted to soil drought (30 % of field soil water capacity) for 5 days at the stage of pod formation (A) and of rapid pod growth (B) and then exposed for 20 minutes to 14CO2. Radioactivity of leaves, stems, roots, and pods or pod shells and seeds was measured 1, 5, 24 and 48 hours after exposition.
In both stages soil drought reduced by about five times total CO2 assimilation, mainly owing to lower activity of the photosynthetic apparatus and also, though less so, to reduced leaf growth. Photosynthetic activity referred to the dry weight of the leaves dropped to 22-35% of controls. Accumulation of photosynthetates in generative organs was much less depressed than 14CO2 assimilation. 48 hours after exposition to 14CO2 of drought treated plants, the contents of 14C of pods in phase A, and seeds in phase B, amounted to respectively 24% and 36% of assimilated 14C and equalled 91.5% and 74% of the corresponding values for controls.
The progressive decline of radioactivity in leaves and stems after 14CO2 exposition was distinctly correlated to the rise of radioactivity of generative organs both in soil drought treated plants and in controls. Slightly lower values of correlation coefficients in drought treated plants may indicate impairment under drought conditions of synchronization in processes of unloading and accumulation of assimilates.
In plants drought treated in phase A the ability to dissimilate 14C was reduced to about 59% of that in controls, but when drought was applied in phase B, dissimilation rate was about three times as high.  相似文献   

17.
The pH and redox relationships of a rice soil subjected to alternate flooding and drying were measured during the growth of three successive rice crops in the greenhouse. The objective was to explain why greater nitrogen losses occur under alternating flooding and drying than under continual submergence.
At 2 cm below the soil-water interface the pH dropped from 8.3 to approximately 7.0 in 40 days and remained there through 120 days. The redox (pe + pH) dropped from 16 to 4 under the same conditions. When alternate flooding and drying were imposed, the pH fluctuated from 8.0 during drying to near 7.6 during submergence while pe + pH shifted from 16 during drying to approximately 8 during flooding. Both pH and pe + pH dropped slightly with depth into the sediment reflecting greater accumulation of CO2 and depletion of O2.
The findings in this study support the hypothesis that alternate flooding and drying causes the redox of rice soils to pass through the pe + pH range of 13 to 15 where theoretical considerations show that NO(g) is most stable and can function as a viable intermediate reaction product of denitrification in soils.  相似文献   

18.
Annual rainfall in Chile at 30°S decreased from 170 to 70 mm in the last century, forcing a search for new low-rain adapted crops. Chenopodium quinoa Willd. was cultivated by pre-Hispanic cultures, but it disappeared in this region since the Spanish conquest. Two quínoa landraces (Don Javi and Palmilla) were re-introduced from lowlands of central Chile (34°S) evaluating seed saponin content and grain yields under low irrigation. Replicated assays were conducted in two sites with distinct microclimates after august (end of the rains in 2004 and 2005). Treatments included low (40–75 mm) and high (150–250 mm) irrigation and were distributed along the five cultivation months. Fertilization, with the humus of the worms, was carried out in the second season, as soils are poor in organic matter. Results showed significantly higher saponin content in the seeds of Don Javi landrace (1.2 %) with respect to Palmilla seeds (0.3 %). However, grain yields were not different between landraces under the same treatments. Yields were instead affected by microclimate, irrigation and fertilization. Although higher yields corresponded with higher irrigation, 2.6 tons ha−1 was obtained under high irrigation, but surprisingly, also under low irrigation in the more humid site. Yields of 2006 harvesting season (ca. 7 tons ha−1) were higher than that of the previous season (ca. 5.5 tons ha−1), mainly because of the addition of organic matter. We suggest that re-introduction of Quinoa in arid Chile is feasible even under the prevailing conditions of low rainfall and deficient soils, but better yields will need some irrigation and addition of organic matter.  相似文献   

19.
Fixed position experiments were conducted in 2017 and 2018, and split plot arrangement with the main treatment for full irrigation (W1) with irrigation amount was 4800 cubic meters per hectare and deficit irrigation (W2) was 2400 cubic meters per hectare, and the secondary treatment including treatments without fertilization (CK), single application of chemical fertilizer (CF), 75% chemical fertilizer with 25% organic fertilizer (M1), 50% chemical fertilizer with 50% organic fertilizer (M2), and 25% chemical fertilizer with 75% organic fertilizer (M3). The effects of chemical fertilizer reduction and organic fertilizer application on photosynthetic characteristics and yield of cotton were studied to provide theoretical basis for rational utilization of organic fertilizer and reduction of chemical fertilizer input under water deficit. Under deficit irrigation, leaf area index (LAI), net photosynthetic rate (Pn), stomatal conductance (Gs), above-ground dry matter accumulation and seed yield of cotton were all lower than that under full irrigation, while irrigation water productivity (IWP) and intercellular CO2 concentration (Ci) were higher. The chemical fertilizer reduction combined with application of organic fertilizer could effectively improve the LAI after the full squaring stage, improve Pn and Gs of cotton in all stage, promote the accumulation of vegetative and reproductive organs dry matter, improve its transfer to the reproductive organs, improve the IWP and seed yield, and also increase the moisture content of soil surface in the period of full boll stage and boll opening stage. The effects among different organic fertilizer treatments on LAI, Pn and seed yield were all presented as M1 > M2 > M3, and under the treatment of M1, the average seed cotton yield of two years increased compared with CF and CK by 6.9% and 62.1% respectively. Whereas, the effects under deficit irrigation were presented as M2 > M1 > M3, and the two years’ average seed yield increased by 19.9% and 79.3% respectively compared with CF and CK under M2. Chemical fertilizer reduction and organic fertilizer application were beneficial to increase the yield of seed cotton under water deficit, and alleviate the influence of water deficit on cotton growth and development, M2 (50% fertilizer +50% organic fertilizer) was the best treatment.  相似文献   

20.
In epidermal cell walls of soybean leaves treated with amorphous silica accumulation of silica could be detected by means of electron microscopy and electron probe microanalysis. This changed the physical properties of the cell wall and affected the cuticular transpiration and uptake of CO2: When the soil in which the plants were grown was dry (60% of the field capacity) and relative air humidity was below 50 %, the loss of water through the cuticle was smaller than the loss of CO2 uptake. This caused a higher grain yield under the conditions of temporarily restricted low air humidity.  相似文献   

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