The Response to CO2 Enrichment of Capillary-Watered Single-Truss Tomatoes at Different Plant Densities and Seasons

CO₂ enrichment advanced the date of first anthesis, promoted earlier cropping and shortened the duration of harvest for single-truss tomatoes sown in December and, to a lesser extent, for those sown in July. It also prevented arrested development of the flowers of a December-sown crop growing in poor light.

CO₂ caused increases in marketable fruit yield that were greatest for a mid- July sowing and least for a mid-December sowing. The increases obtained from plants sown in mid-December were independent of population density. For a mid-July sowing the increases in yield of ripe marketable tomatoes were 33% and 17% at population densities of 10 and 25 plants/m² respectively. Increases in total marketable fruit weight caused by CO₂ resulted from an increase in the number of fruits attaining marketable size and an increase in the average weight of individual fruits.

Some of the advantages of producing fruit on single-truss tomatoes grown in shallow capillary-watered beds are mentioned.     

Light-Modulated Temperature Control and the Response of Greenhouse Tomatoes to Different CO2 Regimes

A light-modulated greenhouse controller that varied the air temperature with incoming solar radiation was used in an experiment to compare the response of Craigella, Eurocross B and J172 tomatoes from first anthesis to the end of fruit harvesting to light-modulated and steady day-time air temperature regimes at CO₂ concentrations of 600 and 1200 volumes per million.

The yield of marketable fruit obtained from the light-modulated temperature regime was on average 26% higher after 6 weeks of picking and 9% higher after 22 weeks of picking than that from the steady temperature treatment. An increase in CO₂ concentration from 600 to 1200 vpm resulted in overall increases of 15% and 8% in the early and final yields of ripe marketable fruit respectively. Tomatoes grown under a light-modulated temperature regime reached the half-harvest date on average 5 days ahead of those grown in a steady temperature regime. The difference in earliness of cropping resulting from CO₂ enrichment to 1200 instead of 600 vpm was 3 days. J172 was the most successful cultivar judged by marketable yield and estimated gross monetary returns.     

CO2 enrichment of greenhouse tomatoes using a closed-loop heat storage: Effects of cultivar and nitrogen

Spring crops of soil-grown greenhouse tomatoes (Lycopersion Lycopersicum (L.) Karst ex. Farw cultivars MO and TR-VE 23) were provided with three levels of nitrogen addition with and without added CO₂. Using a closed-loop solar collection/storage system, crops could be CO₂-enriched for 76–77% of the daylight hours. CO₂ enrichment increased No. 1 grade fruit weight by 14 and 27% and by 4 and 18% for both cultivars in 1981 and 1982, respectively. Although the method and amount of nitrogen application differed between 1981 and 1982, a trend was seen in both years for low nitrogen treatments to produce a greater response to CO₂ enrichment than high nitrogen treatments. A trend was also seen in both years for low nitrogen treatment to depress yield and quality in the non-enriched house, but to have no effect in the enriched house. This trend was particularly apparent in the cultivar with lower vegetative vigor, which also responded more overall to CO₂ enrichment than the cultivar with greater vegetative vigor.     

Effect of elevated CO2 on vegetative and reproductive growth characteristics of the CAM plants Hylocereus undatus and Selenicereus megalanthus

This study examined the vegetative and reproductive growth responses of the crassulacean acid metabolism (CAM) vine-cactus fruit crop species Hylocereus undatus and Selenicereus megalanthus to CO₂ enrichment (1000 μmol mol⁻¹ vs. control of 380 μmol mol⁻¹). H. undatus plants enriched with CO₂ demonstrated 52%, 22%, 18%, and 175% increases, relative to plants measured in ambient CO₂, in total daily net CO₂ uptake, shoot elongation, shoot dry mass, and number of reproductive buds, respectively. The responses of S. megalanthus plants exposed to elevated CO₂ were greater than those of H. undatus under the same conditions. Compared to plant responses in ambient CO₂, under conditions of CO₂ enrichment, S. megalanthus showed 129%, 73%, 68%, and 233% increases in total daily net CO₂ uptake, shoot elongation, shoot dry mass, and number of reproductive buds, respectively. Moreover, for H. undatus, there was no significant change in fruit fresh mass although it showed a slight (7%) upward trend. On the other hand, fruit fresh mass of S. megalanthus significantly increased by 63% in response to elevated CO₂. These results indicate the high potential of CAM plants to respond to CO₂ enrichment. It is thus apparent that S. megalanthus grown under CO₂ enrichment may benefit from elevated CO₂ to a greater extent than H. undatus grown under sub-optimal growth conditions.     

Effect of CO2 enrichment on photosynthesis,growth and yield of tomato

Net photosynthesis of tomato plants was measured as CO₂ uptake in various light intensities, CO₂ concentrations, O₂ concentrations and temperatures during short-term experiments. Net photosynthesis increased significantly with increasing CO₂ concentration at all light intensities, even at the lowest one. The optimal temperature for photosynthesis increased with CO₂ enrichment. The changes in photosynthesis when the $\text{CO}{}_2\text{O}{}_2$ ratio was varied suggest that the effect of CO₂ enrichment is a result of a reduction in photorespiration.To determine whether the increase in photosynthesis caused by CO₂ enrichment would produce a greater yield, tomato plants were cultivated from seed to harvest in a tightly-closed greenhouse that was enriched with CO₂ continuously during the entire growing-period. The control greenhouse was ventilated by openings in the roof and door. The temperature of the 2 greenhouses was kept the same. Plants enriched with CO₂ showed a significant increase in fresh and dry weight and yield of tomatoes. The results are discussed in relation to earlier work in which CO₂ enrichment was discontinued when there was a need for ventilation.     

Effect of intermittent as compared to continuous CO2 enrichment on growth and flowering of Chrysanthemum × morifolium Ramat. and Saintpaulia ionantha H. Wendl

Plants of three cultivars of Saintpaulia ionantha and Chrysanthemum × morifolium were grown until flowering at 335 (normal) or 900 μl l⁻¹ CO₂ (high). Continuous high CO₂ concentration increased the final dry weights from 76 to 123% in Saintpaulia and from 15 to 32% in Chrysanthemum compared to the normal concentration. Changing the CO₂ concentration from normal to high (intermittent) in intervals of 1 h resulted in dry weights intermediate to that of constant normal or constant high CO₂ concentrations in both species. Morning and evening enrichment gave the same effect as 1-h intermittent enrichment in Saintpaulia. High CO₂ concentration given every other day gave the same effect as 1 h intermittent CO₂ in Chrysanthemum. Increased dry weights were accompanied by more and larger leaves in Saintpaulia, and mainly by thicker and longer stem and more lateral breaks in Chrysanthemum.Time to flowering was significantly reduced by CO₂ enrichment in Saintpaulia, but was generally not affected in Chrysanthemum. Number of flowers and flowerbuds was increased by CO₂ application in both species. Constant high CO₂ concentration generally had effects superior to that of the intermittent treatments.     

Effect of Carbon Dioxide Enrichment on Growth,Development and Yield of Glasshouse Tomatoes. II. The Duration of Daily Periods of Enrichment

The effects of various daily durations of CO₂ enrichment ‘on early-sown glasshouse tomatoes are outlined. Reducing the daily enrichment period in the pre-planting stage (late November to mid-January) had only marginal effects on total yields and · monetary values. Reductions in the post-planting stage (mid-January to mid-April) caused significant depressions in yields, roughly proportional to the · reduction in enrichment time. For a given reduction in the duration of daily enrichment, delaying the start of enrichment in the morning was more detrimental than ending it prematurely before sunset.

Varying the frequency of water applications during the CO₂ enrichment period, from every second to every eighth day, had little effect, with no significant interactions between enrichment duration and watering frequency.

Daily durations of CO₂ enrichment somewhat shorter than the full sunrise-sunset periods, during the pre-planting stage, may not significantly reduce the total returns from the crop, but the consequent monetary saving would be quite small. Any reduction during the post-planting stage would be detrimental, resulting in a far greater loss in revenue than the consequent saving in costs.     

The physiology of Cymbidium plantlets cultured in vitro under conditions of high carbon dioxide and low photosynthetic photon flux density

Summary

Cymbidium plantlets were grown in vitro under conditions of high CO₂ and low photosynthetic photon flux density using the Miracle Packt culture system. Shoots and roots of plantlets showed differential growth characteristics. Shoot growth was not different in plantlets cultured under CO₂-enriched (CDE) and non-enriched (NCDE) conditions. Root growth was promoted in plantlets cultured under CDE in the presence or absence of 2% sucrose (S) with rockwool (R) as the supporting material. Growth was poor in plantlets cultured in 1% agar. Root growth was best in plantlets cultured under CDE R+S. Sucrose is still an important component for root growth under CDE conditions even though CO₂ can be used as an alternative carbon source. Photosynthetic measurements (CO₂ uptake and total Rubisco activity) showed the presence of active and operational photosynthetic machinery in plantlets cultured under CDE and NCDE conditions. The apparent lack of photoautotrophy (as evident from the lack of starch grains in chloroplasts) in plantlets cultured under NCDE conditions is not the result of a lesser potential for photoautotrophy; rather it is a consequence of sub-optimal CO₂ concentrations within the culture vessels.     

Response of tomato plants to saline water as affected by carbon dioxide supplementation. I. Growth,yield and fruit quality

Summary

Tomato plants (Lycopersicon esculentum (L.) Mill. cv. F144) were irrigated with low concentrations of mixed salts; the highest level (E.C. 7 dS m^–1) simulated conditions used to produce quality tomatoes in the Negev highlands. CO₂ enrichment (to 1200.mmol mol^–1, given during the daytime) increased plant growth at the early stage of development. However, later growth enhancement was maintained only when combined with salt stress. In the absence of CO₂ supplementation, overall growth decreased with salt (7 dS m^–1) to 58% and fresh biomass yields to 53% of the controls. However, under elevated CO₂ concentrations total plant dry biomass was not reduced by salt stress. CO₂ enrichment of plants grown with 7 dS m^–1 salt increased total fresh fruit yields by 48% and maintained fruit quality in terms of total soluble salts, glucose and acidity. Fruit ripening was about 10.d earlier under CO₂ enrichment, regardless of salinity treatment. It is suggested that a combined utilization of brackish water and CO₂ supplementation may enable the production of high-quality fruits without incurring all the inevitable loss in yields associated with salt treatment.     

Effects of CO2 on greenhouse grown eggplant (Solanum melongena L.) II. Leaf tip chlorosis and fruit production

The effect of CO, on leaf boron content, Leaf Tip Chlorosis (LTC) and fruit production of eggplant (Solanum melongena L., cv. Cosmos) was investigated in the spring of 1991. Two levels of CO₂ (413 and 663 (xmol mol^-1) were maintained in duplicate, in four glasshouse compartments (16 m x 16 m). LTC was significantly more severe at high than at low CO₂. Leaf boron content was lower in leaves with LTC than in other leaves and was lower in leaves from high CO₂ than in those from low CO₂. These results, in combination with observed reduction in leaf conductance (part I), support the hypothesis that LTC is caused by reduced boron translocation to young, fast growing leaves, because of reduced transpiration. More specific research on boron is necessary to confirm this hypothesis. Fruit production was significantly higher (24%) at high CO₂ than low CO₂, despite more severe LTC.     

Effects of source,rate, and frequency of N application on yield,marketable grades and rot incidence of sweet onion (Allium cepa L. cv. Granex-33)

In a field experiment in the 1988-89 season, fertilizer formulations of NH₄NO₃, Ca(NO₃)₂, NaNO₃, NaKNO₃, and KNO₃ as N sources were applied at 84 and 168 kg N ha^?1 to onion plots direct seeded in the fall. A second experiment in the 1990-91 season tested the same N sources, except KNO₃, at rates of 168 and 224 kg ha^?1. Application strategy involved both splitting the total amount of fertilizer over two periods of the growing season (October–December and January—April) and the application frequency. With medium and high application rates (168 and 224 kg ha^?1), NH₄NO₃, NaNO₃, and NaKNO₃, increased high-value jumbo and large onions (premium marketable grade). Increased premium grades was due to increased bulb size and weight. Only NH₄NO₃ and Ca (NO₃)₂ increased total onion weight when N rate was increased from 84 to 168 kg ha^?1. Less frequent applications of split amounts of 84 kg N ha^?1 reduced marketable weight in the 1988–89 season, but doubling the rate to 168 kg ha^?1 restored the higher yields. At 224 kg N ha^?1 in the 1990–91 season, differences in onion grades were more pronounced among the different N sources, and NH4 NO₃ was superior in producing jumbo and large size onions. High N rates (224 kg ha^?1) and more frequent applications of split portions also increased the weight of jumbo onions. Split applications, providing 33% of the total N in the first 12 weeks of the growth period plus three applications of 22% each in the second 12 week period, increased bulb size and maximized yield of premium marketable grades. Effect of N rate on onion rot was dependent on split methods of applying the N during early and late growth periods. However, reduction in onion rot by the split application strategy was dependent on N source. Bulb decay was highest with NH4NO₃ and least with Ca(NO₃)₂ and NaNO₃.     

A simulation study on CO2 concentration in protected cultivation

In protected cultivation in The Netherlands, it is common practice that CO₂ enrichment is supplied by the heating system. The improvements in glasshouse insulation achieved during the last decade decreased both the air exchange of the glasshouse and the heat demand. During periods of low heat demand and high irradiance, the cumulative effect is a decrease of the CO₂ concentration considerably below ambient. Moreover, even with open ventilators, certain climatological conditions may cause a marked decrease of the CO₂ level in the glasshouse.This paper presents some physiological aspects of the problem. With emphasis on the CO₂-concentration level, estimates of the production of a typical glasshouse crop were made, as related to climate control in early spring.Economic aspects of additional CO₂ supply (independent of the heat demand) are presented.     

The effect of the time of taking side shoots on the regulation of fruit size in glasshouse-grown tomato crops

Summary

Young tomato plants were transferred to heated glasshouse compartments on 9 December at a density of 2.04 plants m-2 and grown as a conventional long-season tomato crop. Beginning in either the third, fifth, seventh or ninth week of the year, every other plant was allowed to retain one side shoot so as to increase the effective plant density to 3.06 plants m-2. Control crops were grown throughout at both the initial and the final densities. Two different patterns of taking the side shoots were tested in two sub-treatments: taking the required number of side shoots in four tranches over a period of six weeks was neither significantly better nor worse than taking them in two equal tranches, four weeks apart. The main effect of adding side shoots was to increase the number of fruit harvested per m-2, as compared with a control crop grown throughout at the initial density of 2.04 plants m-2. However, these additional fruit were not harvested until at least 80.d after the first side shoots had been allowed to grow. When side shoots were taken as early as week 3, a high proportion of the marketable fruit were in the preferred size (viz.47to57.mm in diameter, 50 to 90.g in weight, UK grade D) in all harvest periods. Thus, the additional side shoots enabled the crop to bear extra fruit and when the side shoots were taken early, the production of additional fruit coincided with the time when both the quantity of solar radiation incident per day and the concomitant assimilate production were increasing rapidly. Consequently, the supply of assimilates and the numbers of fruit available per m-2 were better matched for the purpose of continually producing fruit of one size. However, the presence of side shoots tended to reduce the number of marketable fruit carried on each truss. The addition of side shoots increased leaf area index and also significantly increased total fruit yield. The increased area of foliage served to shade more fruit from the heating effects of incident solar radiation and a smaller proportion of marketable fruit was downgraded to Class II in all side-shoot treatments. In general, the means of the four successive side-shoot treatments provided a graded series between those of the fixed low-density and the fixed high-density control treatments.     

Diurnal variations in gas exchange,chlorophyll fluorescence quenching and light allocation in soybean leaves: The cause for midday depression in CO2 assimilation

Gas exchange and chlorophyll fluorescence quenching analysis were carried out to investigate the diurnal variations in photosynthesis and light allocation in leaves of soybean. Leaf net CO₂ assimilation rate showed a bimodal diurnal pattern and midday depression of CO₂ assimilation was observed at 13:00 h. Depression in CO₂ assimilation at midday was mostly attributed to non-stomatal limitation since the reduction in net CO₂ assimilation rate was not followed by significant reductions in stomatal conductance and intracellular CO₂ concentration. Midday depression in CO₂ assimilation was found to be associated with reversible inactivation of photosystem II reaction centers and increases of antenna heat dissipation and photorespiration in response to the high light intensity. It is likely that PS II down-regulation, heat dissipation and photorespiration co-operated together to prevent the chloroplast from photodamage.     

Higher than optimum temperature under CO2 enrichment influences stomata anatomical characters in rose (Rosa hybrida)

There is little available information on the effects of temperature and CO₂ enrichment on stomata anatomical characteristics of plants. Effect of these two microclimates was studied on five rose (Rosa spp.) cultivars, viz. ‘First Red’ (used as check), ‘Arjun’, ‘Raktima’, ‘Raktagandha’ and ‘Pusa Pitamber’. Budded, single-stemmed rose cultivars having five lateral buds were grown in controlled environment growth cabinets under enriched CO₂ (1000 μmol mol⁻¹) and optimum (28/18 °C, T₀) or high (35/25 °C, T₁) temperature for 50 days. All observations were made on the abaxial leaf surface. Significant increases in stomatal density (68.7%), index (29.6%) and epidermal cell density (37.3%) were recorded in plants grown at high temperature over control with CO₂ enrichment. The cultivars responded differently in terms of length and width of guard cell and stoma (pore) under high temperature, however, the values averaged over treatments showed a significant reduction in these parameters. Further, number of stomata per leaf was higher (28.3%) in plants grown at high temperature, except First Red. A reduction in mean leaf area (26.7%) and dry mass (32.0%) was recorded at high rather than optimum temperature. The specific leaf area was maximum in Arjun (87%) while in First Red, a 14% reduction was noted at high temperature.     

CO2 enrichment of strawberry and cucumber plants grown in unheated greenhouses in Israel

Strawberries and cucumber plants were grown in ambient atmospheric CO₂ concentrations of 300 v.p.m. and at elevated levels of 900, 1500 and 3000 v.p.m. during winter and early spring in 10 unheated greenhouses in the coastal plain of Israel. Co₂ enrichment averaged 7 hours per day between the end of November and the second half of April.Strawberry plants of cultivar ‘Tioga’ yielded 31, 43 and 51 % more than the control when subjected to a 3-, 5- and 10-fold increase in CO₂ concentration, respectively.Cucumber plants of cultivar ‘Elem’ grown at 3000 v.p.m. CO₂ yielded 26 % more over the whole picking season than those grown at 300 v.p.m. Yield during the first month of picking was doubled by both a 3- and a 10-fold increase in aerial CO₂ concentration.     

Controlled-atmosphere storage of kiwifruit. I. Effect on fruit firmness and storage life

The effect of atmospheres containing high CO₂ and low O₂ on the firmness of kiwifruit (Actinidia chinensis Planch.) during cool storage at 0°C has been studied. Atmospheres containing above 4% CO₂ with 15–20%O₂ caused a retardation in the softening of kiwifruit. This effect increased as the CO₂ content of the atmosphere increased from 4 to 10%, but additional CO₂ above 10% had no further effect on fruit firmness. Low O₂ (2–3%) with 3–5% CO₂ further delayed the rate of kiwifruit softening and increased storage life up to 3–4 months beyond normal air-storage life. Although controlled-atmosphere storage increases storage life of kiwifruit, the magnitude of the effect was found to vary from year to year. Contamination of the storage atmosphere by as little as 0.1 μl^?1 ethylene severely reduced the effectiveness of controlled-atmosphere storage in maintaining kiwifruit firmness, even at 0°C.     

CO2 加富对黄瓜叶片显微和亚显微结构的影响

 以黄瓜为试材, 研究CO₂加富对叶片显微和亚显微结构的影响。结果表明: CO₂加富后黄瓜叶片栅栏组织厚度、表皮厚度和叶片厚度增加, 栅栏组织占叶片总厚度的比例上升, 栅栏细胞变长, 排列更加整齐紧密; 叶片叶绿体数目和大小、淀粉粒数目和大小、基粒及其片层数均增加, 单位叶绿体含淀粉粒数上升, 但叶绿体超微结构未见明显伤害。上午以不同浓度CO₂加富3 h 效应较小, 上、下午各以1 100+100 uL.L^-1CO₂ 加富3 h 效果显著。     

Gas-exchange responses of rose plants to CO2 enrichment and light

Summary

This paper describes the response of gas exchange rates and water use efficiency of rose plants, by means of the characterization in situ and the analysis of the response of photosynthesis, transpiration and water use efficiency of whole plants to CO₂ enrichment under the irradiance conditions prevailing in greenhouses of southern France. Net CO₂ assimilation (A_n) and transpiration (E) of whole rose plants (Rosa hybrida, cv. Sonia) were measured during winter and spring periods. The response of A_n to light and CO₂ were fitted to a double hyperbola function (r² = 0.84). Maximum net assimilation rate (A_nmax), light and CO₂ utilization efficiencies (α₁, α_c) as well as light and CO₂ compensation points (Γ₁ , Γ_c) were calculated for the whole plant and compared with leaf and canopy data in the literature. The whole-plant characteristics generally had values intermediate between those related to leaf and canopy. Light saturation at sub-ambient air CO₂ concentration (C_a) was reached for relatively low PFFD values (300 µmol m^?2 s^?1), whereas at ambient and enriched C_a light saturation occurs for PPFD ≈ 1000 µmol m^?2 s^?1. Doubling C_a from 350 to 700 µmol mol^?1 increased A_nmax and α₁ by respectively 40% and 30%, while reducing Γ₁ by 27%. A threefold increase of C_a from 350 to 1050 µmol mol^?1 induced a reduction of 20% of E. Instantaneous transpirational water use efficiency, WUE (=A_n/E), is relatively insensitive to PPFD, although a slight decrease with PPFD is observed at high CO₂ concentration, but shows marked variations with C_a and leaf to air vapour pressure defiçit (D₁). Increase of C_a from 350 to 1000 µmol mol^?1 gave about 50% increase in WUE. Increase of D₁ from 0 to 2 kPa induced 30% decrease in WUE at ambient C_a and 50% decrease at 1000 µmol mol^?1.     

Effects of CO2 on leaf conductance and canopy transpiration of greenhouse grown cucumber and tomato

The effects of carbon dioxide (CO₂) on stomatal opening and canopy transpiration were investigated in cucumber (Cucumis sativus L., cv. Jessica) and tomato (Lycopersicon esculentum Mill., cv. Calypso). Stomatal opening (i.e. leaf conductance, g) was measured with a porometer, and canopy transpiration rate (E) with weighing lysimeters on intact plants in large greenhouses. Regression analysis was applied to account for the effects of radiation, air humidity, leaf temperature and CO₂ on g. The effect of CO₂ on E, which is primarily through g and secondarily through adjusted air humidity, was investigated by combining the regression equation for g with the Penman-Monteith equation for E. The relative effect of CO₂, as calculated with the fitted regression equations, was a decrease of about 4% in g for cucumber and of about 3% for tomato, per 100 μol mol-1 increase in CO₂, in the range of about 300 to 1200 μmol mol^?1 CO₂. The effect of CO₂ on E was smaller than on g and the extent of the effect depended on the conditions, mainly ventilation rate. The ratio K (relative change in calculated E divided by relative change in calculated g) was estimated at less than 0.2, except at low radiation. In reality, K will be even lower, because feedback mechanisms enforce the reduction in g and counteract the reduction in E. So the reduction of the transpiration rate of greenhouse cucumber and tomato caused by moderate CO₂ enrichment is small and mostly negligible, except under low light conditions.