Differential sensitivity to temperature of cuphea vegetative and reproductive growth

Cuphea (Cuphea viscosissima Jacq. x C. lanceolata W.T. Aiton; PSR23) is a new oilseed crop rich in medium-chain fatty acids similar to tropical palms. Agronomic studies suggest that temperature is a key determinant of cuphea seed yields. However, little is known about the growth and photosynthesis response of cuphea to temperature. The following study is the first of its kind to evaluate cuphea's growth and photosynthesis response to temperature. Cuphea was grown under day/night temperature regimes of 18/12, 24/18, and 30/24 °C and regression analysis was used to assess its responses of growth and photosynthesis and determine their optimum temperature range. Vegetative growth and leaf photosynthesis adapted well over the temperature range studied. However, reproductive growth was more sensitive showing a decline with increasing temperature. Reproductive growth rate was greatest under the lowest (18/12 °C) temperature treatment and declined by 43% at the highest growth temperatures. In contrast, vegetative growth, which was greatest under the 24/18 °C treatment, declined by just 25 and 10% at the lowest and highest temperatures, respectively. Photosynthesis acclimated to temperature by up-regulation of in vivo Rubisco activity with declining growth temperature. Maximum Rubisco activity (V_cmax) in leaves under the 18/12 °C treatment was 76% greater than that of leaves grown at 30/24 °C. Photosynthetic acclimation permitted cuphea to vegetatively grow well over a wide temperature range, but does not explain the sensitivity of reproductive growth to temperature, which will require further research to elucidate.     

Potential uses for cuphea oil processing byproducts and processed oils

Cuphea spp. have seeds that contain high levels of medium chain fatty acids and have the potential to be commercially cultivated. In the course of processing and refining cuphea oil a number of byproducts are generated. Developing commercial uses for these byproducts would improve the economics of growing cuphea. Oil fractions and byproducts were obtained from processed seeds of cuphea germplasm line PSR 23 (Cuphea viscosissima × Cuphea lanceolata). We investigated the employment of oil byproducts as growth regulators and solid residues as organic soil amendments on Calabrese broccoli (Brassica oleracea L, family Brassicaceae) seedling growth. Seed processing solid residue fractions, included presscake, bin trash, stem trash and seed trash. These fractions were ground and mixed into soil to obtain concentrations of 0, 0.5, 1, 3, and 10% (w/w). Ground presscake and bin trash could be employed as an organic soil amendment up to 1% without detrimental effects on broccoli. Ground seed meal (seed trash) was detrimental to seedling growth at all concentrations tested. Stem trash employed at 1% caused fresh and dry weights to increase 26.8 and 29.8%, respectively, compared to untreated broccoli seedlings. Stem trash could be employed up to 10% without a detrimental effect on broccoli seedlings. Solvent extraction to remove residual oils from residue fractions was also conducted to generate improved soil amendments. Generally, solvent extraction of seed-processing residue fractions improved the broccoli seedling growth responses. Administration of processed oils and their byproduct fractions as foliar sprays on broccoli seedlings was conducted at rates of 0, 10, 30, and 50 g L⁻¹. Plants were evaluated 72 h after spraying. Refined and crude oils had no effect on broccoli seedlings; gums and soapstock sprays had no effect at 10 or 30 g L⁻¹ concentrations but at 50 g L⁻¹ it killed seedlings. Distilled fatty acid fraction sprays killed broccoli seedlings at all tested concentrations. Certain oil byproduct fractions from cuphea oil processing can be employed as “environmentally-friendly” herbicidal sprays. Calorific evaluation of cuphea ag-wastes were conducted and found to compare well to other biomass energy sources.     

Seeding depth and soil packing affect pure live seed emergence of cuphea

Cuphea viscosissima Jacq. × C. lanceolata f. silenoides W.T. Aiton is a new crop being developed in the north-central USA as an industrial oilseed crop. Adequate plant stand is essential for successful commercial production of cuphea. The objective of this study was to determine the effect of seeding date, depth and soil packing on stand establishment and subsequent crop performance. The study was conducted at Carrington and Prosper, ND, in 2005 and 2006. The experimental design was a randomized complete block with four replicates, with a split–plot arrangement, where the whole plot was a factorial arrangement (2 × 2) of two seeding dates, optimum and late, with or without soil packing after seeding. The subplot treatments were three seeding depths (surface, 13, and 25 mm). The same plot planter was used to adjust seeding depth to 13 and 25 mm. Each experimental unit had six rows 4.6-m long with a between-row spacing of 0.31 m. Traits evaluated were pure live seed emergence (PLSE), plant stand, plant height at harvest and seed yield. The main effect for seeding date did not have an effect on PLSE and resulted in adequate stands from both late May and mid June plantings averaged across environments. The seeding depth by soil packing interaction was significant for PLSE, plant stand and seed yield. Pure live seed emergence, plant stand, and seed yield were greater if the soil was packed compared with non-packed for the surface seeded treatment. The soil packing treatment did not influence PLSE, plant stand, or seed yield at the 13- and 25-mm seeding depths. Plant stands obtained from the non-packed surface and 13-mm seeding depths was adequate for high seed yield, as the plants branched to compensate for the lower plant density. Although surface seeding with packing produced satisfactory plant stands, reliance on timely rainfall is required for this to be successful. For this reason, the recommendation for seeding at the 13-mm depth without soil packing would ensure a better chance for sufficient soil water absorption by the seed to initiate germination. If surface seeding is practiced, a roller-packer to incorporate seeds and firm the seedbed after planting is recommended.     

Importance of vanadium and nutrient ionic ratios on the development of hydroponically grown cuphea

Cuphea (Cuphea viscosissima × C. lanceolata ‘PSR 23’) seed contains oils that have industrial application. However, little is known regarding cuphea’s optimal mineral nutritional requirements or responses to inhibiting elements. Oil seed crops often need additional phosphorus (P) to achieve optimal economic yield. Vanadium (V), a commonly occurring soil constituent, interferes with plant P uptake and earlier work showed that V is a factor in lipid metabolism. Hydroponic culture was used to evaluate the relative effect of V on the development of cuphea. Relative root length, root surface area, root weight, and aerial dry weights decreased exponentially as the V concentration increased from 0 to 153 μM. In contrast to field observations of other crops, additions of MgSO₄ to increase the Mg:(Mg+Ca) ratio further decreased plant growth by as much 50% at V concentrations greater than 31 μM. Root length was decreased by about 50% of the control when the plant was grown in 153 μM V and relative root area and dry weight were decreased by ≥75%. Increases in V concentration sharply reduced secondary and higher order lateral branching. Reduction in root growth was accompanied by a general chlorotic appearance. The results suggest that readily available V in field situations will result in poor root growth and crop performance. Also, the interaction of V and MgSO₄, common in soils in the region, will lead to further reductions in yields in the field.     

Effect of nitrogen source on growth and morphogenesis of three micropropagated potato cultivars

Summary Different nitrogen sources (NO₃ ⁻, NH₄ ⁺, glutamic acid and their combinations) influenced the growth and morphogenic responses (node number, shoot length, and stem, leaf and root dry weight) of three micropropagated potato cultivars (Spunta, Kennebec, Huinkul). Addition of reduced nitrogen (NH₄ ⁺ or glutamic acid) in a nitrate medium increased shoot length and leaf number. The large increase in growth in plants fed with NO₃ ⁻, NH₄ ⁺ could be explained by higher organic nitrogen content and enhanced dry matter partition to the shoot. This suggests that reduced nitrogen source is required, at least as a supplement to NO₃ ⁻, to enhance N assimilation and growth.     

Effects of elevated CO2 concentration on growth and photosynthesis of Chinese yam under different temperature regimes

Chinese yam (‘yam’) was grown at different carbon dioxide concentrations ([CO₂]), namely, ambient and elevated (ambient + 200 μmol mol^?1), under low- and high-temperature regimes in summer and autumn, separately. For comparison, rice was also grown under these conditions. Mean air temperatures in the low- and high-temperatures were respectively 24.1 and 29.1 °C in summer experiment and 20.2 and 24.9 °C in autumn experiment. In summer experiment, yam vine length, leaf area, leaf dry weight (DW), and total DW were significantly higher under elevated [CO₂] than ambient [CO₂] in both temperature regimes. Additionally, number of leaves, vine DW, and root DW were significantly higher under elevated [CO₂] than under ambient [CO₂] in the low-temperature regime. In autumn experiment, tuber DW was significantly higher under elevated [CO₂] than under ambient [CO₂] in the high-temperature regime. These results demonstrate that yam shows positive growth responses to elevated [CO₂]. Analysis of variance revealed that significant effect of [CO₂] × air temperature interaction on yam total DW was not detected. Elevated-to-ambient [CO₂] ratios of all growth parameters in summer experiment were higher in yam than in rice. The results suggest that the contribution of elevated [CO₂] is higher in yam than in rice under summer. Yam net photosynthetic rate was significantly higher under elevated [CO₂] than under ambient [CO₂] in both temperature regimes in summer. Elevated [CO₂] significantly affected on the rate in yam but not in rice in both experiments. These findings indicate that photosynthesis responds more readily to elevated [CO₂] in yam than in rice.     

Influence of moisture stress during growth on14CO2 fixation and translocation inSolanum tuberosum L.

Moisture stressing of potato plants resulted in reduced¹⁴CO₂ fixation and translocation of labelled photosynthates from leaves to tubers. A majority of the label was recovered in the sugar fraction of both leaves and tubers. The amount of labelled¹⁴C recovered in the organic acid fraction of tubers of normally irrigated plants was significantly higher than in tubers which had been moisture stressed. In the other fractions, the differences were not significantly different. Injection of uniformly labelled sucrose into the basal portion of attached tubers of stressed and non-stressed plants showed greater translocation of labelled carbon by tubers of stressed plants from basal to the apical portion and also into the stems as compared to non-stressed plants.     

High-temperature-tolerant mungbean (Vigna radiata L.) lines produce better yields when exposed to higher CO2 levels

Increasing global air temperatures, along with rising CO₂ levels, are causing concerns about reducing available freshwater resources and altering cropping patterns. They may influence overall growth and production pattern of crop plants. These likely changes would become major limiting factors for future sustainable food production largely in the tropics and subtropics. Thus, understanding physiological responses hold the key to determining the functional relationship between the environment and crop performance. We explore here the impact of rising CO₂ on the growth and yield traits of a few selected high-temperature (HT)-tolerant mungbean lines, which we earlier screened for HT tolerance using a physiological assay under managed growth conditions. The HT-tolerant lines grown under elevated CO₂ levels (550 and 700 μL L^?1) showed a considerable improvement in growth rates (13.5%, 67.8%, and 46.5% in plant height, leaf area, and total dry matter, respectively) and pod and seed yield (48.7% and 31.7%, respectively), compared to local checks under the same environments. Interestingly, the symptoms of accelerated pod maturity were also observed in most of these lines. The outcome of the study would undoubtedly open up opportunities for increased yield potentials of legumes under the conditions of the warming climate and elevated levels of carbon dioxide.     

Effects of elevated CO2 concentration on bulbil germination and early seedling growth in Chinese yam under different air temperatures

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].     

Light effects on the growth and morphogenesis of potato(Solanum tuberosum) in vitro: A review

Growth, morphogenesis, and tuberization of potato tissuesin vitro are affected by light. Measurements of the various aspects of light that control development and growth of potato are outlined. Physical parameters like light sources, delivery of the light source, and the degradation of culture media by light are discussed. Irradiance, photoautotrophic growthin vitro, spectral wavelength, and photoperiod modify the responses of potato tissues in culture. Acclimatization of tissue culture plantlets, vegetative growth, and the production, quality, and dormancy of microtubers are modified by light. New light sources such as light-emitting diode (LED) lamps are becoming available forin vitro research and for micropropagation of potato. Pulsed or chopper light has the potential to save energy costs. Light effects on potato protoplasts, anther culture, virus eradication, andin vitro conservation are discussed. Potential new research areas are the effect of the spectral quality of light on regeneration of shoots and somatic embryosin vitro, end-of-day red and far-red light treatments, axillary shoot formation in cultured plantlets, and the use of LEDs. The influence of monochromatic spectral filters on growth and development of potatoes in tissue culture could potentially lead to improvements in productivity. The relationship between daily quantum light integral and photoperiod and their effects on growth and morphogenesis of the potato will provide some useful areas of research.     

The influence of the radiation environment around the node on morphogenesis and growth of white clover (Trifolium repens)

The growth of clonally propagated clover plants ( Trifolium repens ) in the glasshouse was compared with their growth under canopies of Tropaeolum peregonium with or without supplementation from red light emitting diodes (LEDs) directed at the youngest node bearing a fully expanded leaf. The T. peregonium was grown over a net support so that its roots did not meet those of the clover. A similar experiment was set up in a permanent grassland using canopy shade from various grass species ( Holcus lanatus, Lolium perenne and Agrostis stolonifera ) with and without supplementation. The LEDs increased the ratio of red to far red radiation (R/FR) received by the treated node with no apparent increase in photosynthetically active radiation (PAR) during the day.
The morphogenetic effects of canopy shading (notably fewer branched nodes and less well-developed branches) were largely removed by supplementation so that the supplemented plants came to resemble those grown in full daylight, particularly in the glasshouse experiments. The results highlight the Importance of the radiation environment at the base of the canopy in the morphogenetic responses of plants to putative competition, and the data are consistent with the hypothesis that responses are communicated acropetally along the stolon.     

A systematic approach to determine the impact of elevated CO2 levels on the chemical composition of wheat (Triticum aestivum)

Two wheat genetic lines (responsive and non-responsive to elevated CO₂) grown under ambient and free-air CO₂ enrichment (FACE) conditions were compared using fuzzy chromatography mass spectrometry (FCMS) metabolite fingerprinting. A more comprehensive survey of the changes in their chemical composition was made on selected samples using ultra-high-performance liquid chromatography (UHPLC) metabolomic profiling with high resolution accurate mass/tandem mass spectrometry (HRAM/MSⁿ). Principal component analysis (PCA) of the metabolite fingerprints showed four clusters for the two genetic lines (responsive and non-responsive) and the two CO₂ levels (ambient and elevated) in score plots. Metabolite profiling of representative samples for each of the four clusters identified 25 and 16 compounds from negative and positive data, respectively, including amino acids, saccharides, phenolic acids, flavonoids, and lipids. Loading plots demonstrated that some saccharides and lipids were responsible for discriminating between not only two genetic lines but also two CO₂ levels. Analysis of free amino acids (not bound) showed a clear pattern of reduced concentration for both lines with elevated CO₂. After acid hydrolysis, the responsive line 6 (41% increase in yield) showed the same pattern observed for free amino acids, but the non-responsive line 5 (6% increase in yield) showed different trends in concentrations of amino acids with elevated CO₂.     

Relationships between disease levels on seed tubers,on crops during growth and in stored potatoes. 2. Skin spot

Summary Incidence of skin spot (Polyscytalum pustulans) was assessed macroscopically (skin spot) or microscopically (P. pustulans infection) on seed tubers, on progeny tubers and stems during growth and on tubers at harvest or after storage in up to 26 commercial King Edward crops in each of 5 years and up to 13 crops grown from ‘healthier’ seed in 4 years. Skin spot affected c. 50% seed tubers and at harvest c 20% tuber eyes were infected withP. pustulans. Skin spot was more frequent on tubers stored at 3°C than at 10°C and was decreased by an initial curing period of 2 weeks at 15°C. The incidence of stem lesions in 3 of 4 years and of tuber eye infection in 2 of 5 years (during growth) or 1 of 5 years (at harvest) was related to that of skin spot on seed tubers. Incidence of skin spot after storage was related to the frequency of eye infection during growth and at harvest in 3 years. After storage, disease incidence in crops grown from a stem cutting stock (‘healthier’ seed) was positively correlated with that of the commercial crops grown on the same field.

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Zusammenfassung Zwischen 1971 und 1975 wurde in bis zu 26 Proben marktf?higer Ernten der Sorte King Edward das Auftreten der Tüpfelfleckenkrankheit auf Pflanzenkartoffeln und gelagerten Tochterknollen untersucht, sowie die Infektion mitPolyscytalum pustulans von Augen an Pflanzgut, an Tochterknollen w?hrend des Wachstums und zur Ernte und das Auftreten von L?sionen an der Stengelbasis (Adams et al., 1980). Zwischen 1972 und 1975 wurden diese Erhebungen auch an Erntegut, das aus ‘gesünderem’ Pflanzgut (das von Stecklingen abstammte) und benachbart zu Marktware aufgewachsen war, durchgeführt. Das durchschnittliche Auftreten von Infektion oder Krankheitsbefall auf Marktware (Tab. 1) zeigte, dass ca. 50% der Pflanzkartoffeln mit Tüpfelfleckenkrankheit befallen waren und zur Ernte waren ca. 20% der Knollenaugen mitP. pustulans infiziert. 1974 trat die Krankheit im Lager st?rker auf als in anderen Jahren, wahrscheinlich weil die Erntebedingungen sehr nass waren und die mit ins Lager gebrachte Erde Inokulum entheilt. Lagerung der Knollen bei 3°C erh?hte den Befall st?rker als bei 10°C und eine Wundheilperiode von 2 Wochen bei 15°C vor der Lagerung bei 3°C senkte den Krankheitsbefall sterk. ‘Gesünderes’ Pflanzgut war 1972–74 nicht von Tüpfelfleckenkrankheit befallen und das Ausmass von Infektion oder Krankheitsbefall war in den folgenden Ernten geringer als in der Marktware (Tab. 2). Die Signifikanz der Regressionen zwischen den Erhebungen des Krankheitsbefalls oder der Infektion, die nach verschiedenen Methoden oder zu verschiedenen Zeiten (Tab. 3) gemacht wurden und Diagramme der signifikanten Regressionen der einzelnen Jahre (Abb. 1 und 2) zeigten, dass das Auftreten von Augeninfektion und Tüpfelfleckenkrankheit auf Planzkartoffeln in allen Jahren signifikant verknüpft war (Abb. 1a). Ebenso war das Vorkommen von Stengell?sionen und Augeninfektionen w?hrend des Wachstums miteinander verbunden (Abb. 2a). Die H?ufigkeit von Stengelinfektionen stand in 3 von 4 Jahren in Beziehung zum Ausmass der Tüpfelfleckenkrankheit (Abb. 1b) und der Augeninfektion (Abb. 1c) des Pflanzgutes. Die Augeninfektion w?hrend des Wachstums war aber nur in wenigen Jahren (Abb. 1d) mit dem Krankheitsbesatz des Pflanzgutes verbunden. Geringere Beziehungen bestanden sogar zwischen den Ergebnissen bei der Ernte oder nach der Lagerung und denen des Pflanzgutes (Abb. 1e). Das Ausmass der Augeninfektion bei der Ernte stand in Beziehung zu dem w?hrend des Wachstums. der Verlauf der Regressionslinien (Abb. 2b) zeigte eine Zunahme zwischen den Daten der Probennahmen 1971 und 1975, aber eine deutliche Abnahme 1973, weil wahrscheinlich neu gebildete Augen nicht infiziert wurden. In drei Jahren war der Krankheitsbesatz im Lager mit dem der Augeninfektion w?hrend des Wachstums (Abb. 2c) oder zur Ernte (Abb. 2d) verknüpft. Diese Ergebnisse zeigen die Bedeutung der Pflanzkartoffel als Quelle des Inokulums und das Misslingen, Beziehungen zwischen den Erhebungen auf Pflanzkartoffeln und einigen anderen herzustellen war vielleicht auf Unterschiede in den Waschstumsbedingungen der Farmen zurückzuführen. Wurden die Ergebnisse ‘gesünderen’ Pflanzgutes mit denen benachbarter Marktware verglichen, so zeigte sich eine signifikante Beziehung unter Verwendung der Ergebnisse nach der Lagerung. Sie gibt Hinweise auf eine allgemeine Quelle des Inokulums, eine Verbreitung zwischen benachbarten Ernten oder auf die Wichtigkeit der allgemeinen Bodenbedingungen.

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Résumé De 1971 à 1975, on a évalué l'incidence de l'oosporiose sur les semences et sur les tubercules-fils en cours de conservation, la contamination dePolyscytalum pustulans sur les yeux des tubercules de semence et sur les tubercules-fils en cours de végétation et à la récolte, et l'importance des lésions à la base des tiges. L'étude a été faite sur 26 cultures commerciales de la variété King Edward (Adams et al. 1980). De 1972 à 1975, on a également étudié des cultures issues de semence ‘plus saines’ (dérivées de boutures) cultivées à c?té des lots commerciaux. L'incidence moyenne de la contamination ou de la maladie sur les lots commerciaux (tableau 1) a montré que 50% des tubercules de semence étaient atteints d'oosporiose, et que 20% des yeux étaient contaminés parP. pustulans à la récolte. La maladie s'est développée pendant la conservation en 1974 beaucoup plus que les autres années, probablement à cause des conditions d'humidité à la récolte ayant entra?né l'introduction de sol contaminé dans le local de stockage. La maladie s'est plus développée à 3°C qu'à 10°C dans le local de conservation, et une cicatrisation de deux semaines à 15°C avant stockage à 3°C a grandement diminué l'importance de la maladie. Les semences ‘plus saines’ ont été indemnes d'oosporiose en 1972/74 et les récoltes suivantes ont été moins touchées que les cultures commerciales (tableau 2). Les régressions effectuées sur les notations de maladie ou de contamination, par des méthodes différentes ou à des époques différentes (tableau 3) et les courbes de régressions significatives année par année (Fig. 1 et 2) montrent qu'il y a une corrélation significative tous les ans entre la contamination des yeux et l'apparition de l'oosporiose sur les tubercules de semence (Fig. 1a); de plus, les attaques sur les tiges et la contamination des yeux en cours de végétation sont également correlées (Fig. 2a). La fréquence de contamination des tiges est liées à l'apparition de l'oosporiose (Fig. 1b) et à la contamination des yeux sur les semences (Fig. 1c), trois années sur quatre, mais la relation entre la contamination des yeux en végétation et l'incidence de la maladie sur la semence est moins fréquente (Fig. 1d). Il y a eu de même moins de relations entre les notations à la récolte ou après stockage et celles sur semence (Fig. 1e). L'incidence de la contamination des yeux à la récolte s'est montrée liée à celle notée en végétation, les pentes des courbes de régression (Fig. 2b) montrant un accroissement de la contamination d'une date d'échantillonnage à l'autre en 1971 et 1975, alors qu'en 1973, on observe une décroissance apparente, probablement parce que les yeux récemment formés sont demeurés sains. Pour les 3 années, l'incidence de la maladie en conservation se montre liée à celle de la contamination des yeux en végétation (Fig. 2c) ou à la récolte (Fig. 2d). Ces résultats montrent l'importance du tubercule de semence en tant que source d'inoculum et les difficultés d'établir des relations entre les estimations sur les tubercules de semence et les autres, probablement dues aux conditions différentes de végétation entre les fermes. Quand on compare les notations des cultures ‘plus saines’ et celles de la série commerciale adjacente, on trouve une relation significative au niveau de l'incidence de la maladie en conservation, liée de toute évidence à une source commune d'inoculum, à une propagation entre cultures voisines ou à l'importance des conditions de sol.

     

Eclipse Effects on CO2 Profile within and above Sorghum Canopy

Abstract

We analyzed the effects of a partial solar eclipse (22 July 2009) on microclimate including vertical gradients of CO₂ concentrations ([CO₂]), so called [CO₂] profile, in a mature sorghum canopy. Together with CO₂ measurement, major photosynthetic drivers of microclimate, light intensity, temperature and atmospheric H₂O concentration ([H₂O]) were also measured simultaneously at the same place and height. [CO₂] at 6.0, 3.2, 2.1, 1.4, 0.7, 0 m above the ground (canopy height was 3.2 m) increased by 5.8, 4.8, 9.0, 7.8, 6.4, 7.6μmol mol-¹, respectively, from 1 hour before the eclipse maximum to the eclipse maximum, during which theincident solar radiation above the canopy dropped by 1473 μmol photons m-² s-¹. However, it declined by 3.4, 10.6, 10.8, 6.0, 5.4, and 5.8μmol mol-¹, respectively, from the eclipse to 1 hour later,during which the incident radiation increased by 1350μmol photons m-² s-¹. The [CO₂] profile during the eclipse was uniform except for higher [CO₂] near the ground. Comparative analysis of theeffect of light intensity on the microclimate during the eclipse-induced light decreasing phase (ELDP) and eclipse-induced light increasing phase (ELIP) revealed that [CO₂], [H₂O], temperature and relative humidity (RH) are significantly correlated with the light intensity above the canopy in a nearly linear fashion. Furthermore it indicated that detected less light-reacted canopy photosynthesis at a higher layer within the canopy during ELIP might be due to slower response of stomatal opening (than closing) to the light intensity above the canopy.     

Increase in Atmospheric CO2 and Ambient Temperatures in the North

SUMMARY

Crop production in the North is constrained by a short growing season, spring and autumn frosts, long winters with deep snow cover and low temperatures during the growing season. Increase in concentration of atmospheric CO₂ and other greenhouse gases, and the subsequent increase in ambient temperatures could benefit crop production in countries located in the North, including Finland. However, longer growing seasons, milder winters and higher growing season temperatures could increase the occurrence of pests and pathogens, and ultimately decrease crop yields and the net income of farmers. Benefits to be gained from increased tillering and higher numbers of grains per unit area resulting from elevated CO₂ levels might be smaller than expected in countries like Finland, where the uniculm growth habit of cereals is maintained by the long days that characterise the growing season.     

Dry gibberellic acid combined with talc or fir bark enhances early stem and tuber growth of Shepody potato

Gibberellic acid (GA₃) powder was applied to seed pieces of Shepody potato in combination with water, fir bark and talc carriers. In a greenhouse study, emergence, stem growth and tuber number from seed pieces treated with dry GA₃ and carriers were compared with that of an untreated control. All carriers alone reduced stem emergence. GA₃ (0.5,1 and 2 mg/ kg) combined with talc, and 0.5 and 2 mg GA₃/kg with fir bark+talc enhanced emergence. Only 2 mg GA₃/kg enhanced emergence when applied in solution. Emergence of stems from pieces treated with GA₃ and fir bark was no different or slower than the control. In the absence of GA₃, water and talc increased stem number and fir bark-containing treatments reduced tuber number. All concentrations of GA₃ applied with talc or fir bark+talc, and 2 mg GA₃/kg with fir bark increased stem and tuber number. With water, 0.5, 1 and 2 mg GA₃/kg increased stem number but only 2 mg GA₃/ kg resulted in more tubers. One and 2 mg GA₃/kg combined with talc resulted in the most stems and tubers 58 days after planting. GA₃ was as effective or more effective in speeding emergence and increasing stem and tuber number when applied in the dry form with talc or fir bark+talc as when applied in solution.     

大气CO2浓度对茶叶品质的影响

通过开顶式气室控制CO₂浓度,对盆栽茶树进行试验测定,研究了大气CO₂浓度升高对茶叶品质成分氨基酸、茶多酚、咖啡碱、可溶性糖和主要营养元素含量的影响。结果表明,在大气CO₂浓度为550和750βμmol/mol时,与正常大气CO₂水平相比,春茶氨基酸含量下降4.5%和12.2%,夏茶氨基酸含量降低1.7%和6.7%,秋茶降幅为2.9%和10.8%;茶叶咖啡碱含量降低3.1%~4.6%和5.1%~10.7%;但茶叶茶多酚和可溶性糖含量降CO₂浓度升高而提高,茶多酚含量提高3.8%~6.0%和6.9%~11.3%,可溶性糖含量增加8.4%~14.4%和18.1%~28.2%。同时,大气CO₂浓度的升高使茶叶营养元素氮、钾、钙、磷、钠含量有不同程度降低,而锌、镁、铁含量有所增加,其中,茶叶氮、钾元素含量降低6.1%~16.3%和12.9%~22.9%,锌、镁含量分别提高5.8%~17.8%和11.3%~16.0%。     

不同氮水平对甘蔗生长的影响

在甘蔗不同生长时期,对不同的施氮水平对甘蔗的影响进行研究,揭示不同生长时期与氮素的关系,建立不同生长时期的关系模型.研究表明,在苗期,甘蔗需氮迫切,但需氮量少,在施氮253.0kg/hm2时,苗量达到最高水平;在甘蔗伸长期,施氮水平在424.6kg/hm2以内,甘蔗株高随着氮素的增加而增高;在施氮457.4kg/hm2内,产量随施氮增加而增加;甘蔗糖锤度与施氮水平呈负相关,施氮量增加,糖锤度降低.