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1.
Sweet basil (Ocimum basilicum L.) is an herb that is used to add a distinct aroma and flavor to food. Volatile compounds emitted from fully expanded fresh leaves grown in drip-irrigated plots that were covered with six colors of mulch were compared. The colors reflected a range of photosynthetic photon flux, far-red, red, and blue light from the soil surface to developing leaves. Our objective was to determine whether reflection from the different colors could influence concentrations of volatile compounds emitted from the fresh leaves. Volatile compounds were isolated by headspace sampling and quantified by gas chromatography. Twenty-six compounds were identified, of which the terpenoids linalool and 1,8-cineole comprised more than 50% of the total yield. Concentrations of volatile compounds from leaves that developed over green, blue, yellow, white, and red mulches followed the same patterns as they did for air-dried leaves of the same cultivar. However, the concentration of volatile compounds from fresh leaves was about 50-fold higher than those found in the previous study of air-dried leaves.  相似文献   

2.
温度与光照对黄素梅、黄金榕叶色变化的影响   总被引：9，自引：0，他引：9  
黄色叶树种黄素梅（Duranta repens cv.Golden Leaves）和黄金榕（Ficus microcarpa cv.Golden Leaves）在园林绿化上具有较高观赏价值。但它们在不同季节叶片颜色差异较大。应用分光光度计法，对其在不同季节叶片光合色素含量的生理指标进行测定。结果表明，光和温度是影响黄素梅、黄金榕叶色变化的直接原因，光照越强、温度赵高，叶色越黄越美丽，因此应将其栽植于阳光充足的环境中。  相似文献   

3.
Strawberry (Fragaria ananassa Duch) is a high-value food crop, the aroma of which is important in consumer satisfaction. We hypothesized that the concentration of fresh strawberry aroma compounds could be enhanced by growing the berries over a red plastic mulch that was formulated to reflect more far-red (FR) and red light (R) and a higher FR/R photon ratio than is reflected by standard black plastic mulch. Strawberries of the cultivars "Chandler" and "Sweet Charlie" were grown in trickle-irrigated field plots over the two colors of mulch. The berries were harvested when ripe, and aroma compounds were isolated by dynamic headspace sampling. Entrained compounds were quantified by gas chromatography and identified by gas chromatography/mass spectroscopy. Twenty-three compounds were identified, and most of them were aliphatic esters. Strawberries that ripened over the red mulch during periods of sunny weather had significantly higher concentrations of aroma compounds than berries grown over the black plastic mulch. Total levels of aroma compounds from berries grown over red plastic mulch were higher for both Chandler and Sweet Charlie. We postulate that FR and R in light reflected from the red mulch acted through the natural phytochrome system to modify gene expression enough to result in greater concentration of aroma compounds in fresh strawberries.  相似文献   

4.
Basil (Ocimum basilicum L.) leaves were dried using a microwave oven at atmospheric pressure or two traditional methods: air-drying at 50 degrees C and freeze-drying. The microwave-drying was carried out at different powers and times on raw basil leaves, while for air and freeze-drying techniques, both raw and blanched leaves were used. The raw and dried basil was analyzed for selected aroma compounds by gas chromatography/mass spectrometry-selected-ion-monitoring, the chlorophyll a and b by HPLC and the color by a reflected-light colorimeter. For dried samples microwaved for 1 min at 270, 2 min at 440, 1 min at 650, and 1 min at 1100 W, the percentage retentions of the characteristic volatile compounds (eucalyptol, linalool, eugenol, and methyl eugenol) were higher than in the samples dried by traditional methods, with the exception of freeze-dried unblenched basil. Microwave drying allowed a larger retention of chlorophyll pigments than air-drying and freeze-drying (with or without blanching) and preserved the color of the raw basil. Microwave drying requires a much shorter treatment and implied the simultaneous blanching of the material.  相似文献   

5.
Aquaponics is the combined culture of fish and plants in recirculating systems. This experiment was conducted to evaluate the production of basil out of the aquaponic system by irrigation of the plants with different ratios of hydroponic and aquaponic solutions. Basil seedlings were irrigated three times day?1 with 200 mL aquaponic-aquaponic-aquaponic (AAA), aquaponic-hydroponic-aquaponic (AHA), hydroponic-aquaponic-hydroponic (HAH), and hydroponic-hydroponic-hydroponic (HHH) solutions, respectively. Fresh and dry mass of shoots and roots of basil decreased at AAA treatment significantly. The plants were slightly less green at AHA treatments, and a visible chlorosis appeared in the leaves of AAA-treated plants. This chlorosis resulted lower net carbon dioxide (CO2) assimilation rate, transpiration rate, and stomatal conductance in AAA treatment. Iron (Fe), manganese (Mn), and potassium (K) concentrations in leaves decreased and zinc (Zn) concentration increased in higher ratios of aquaponic:hydroponic solution. Lower Fe, Mn, and K concentrations in aquaponic solution may be a main part of the reason for growth reduction.  相似文献   

6.
烟粉虱是黄瓜的主要害虫,利用非化学措施控制烟粉虱对于黄瓜绿色生产具有重要意义。为探讨光驱避对设施蔬菜烟粉虱的控制作用,应用RGB值与虚拟波长的关系在计算机上模拟不同波长的颜色,根据烟粉虱对不同光质的选择率,筛选出对烟粉虱有驱避作用的敏感光质,在此基础上,调查该光质处理下设施黄瓜烟粉虱种群的变化情况以及该光质与多种光质联合使用对烟粉虱的控制作用。结果表明,RGB值为0,0,255(波长为470nm的蓝色)的颜色对烟粉虱成虫的驱避率最高。黄色和绿色对烟粉虱有较强的诱集作用,烟粉虱的选择率分别为54%和42%;但在黄光和绿光打开的环境中再加入蓝光后,烟粉虱对黄光和绿光的选择率分别提高到68%和56%。在黄光和绿光共存的环境中加入蓝色光,可以加速烟粉虱从绿色区域向黄色区域的迁移。在大棚黄瓜田,蓝光照射后烟粉虱的种群数量迅速下降,并且随着光照射时间的延长,黄瓜上烟粉虱数量下降幅度增大,光照射6 d后烟粉虱的校正虫口减退率达92.76%。蓝光和黄光联合使用,在开启蓝光前先打开黄光,可以增强对黄瓜烟粉虱种群的控制作用,处理10 d、20 d、30 d后,黄瓜叶片上烟粉虱校正虫口减退率较不开黄光分别提高13.80%、18.17%、15.10%。研究发现,蓝光照射对烟粉虱有强烈的驱避作用,蓝光和黄光配合使用可以提高对烟粉虱的控制作用。  相似文献   

7.
Pot chrysanthemums (Chrysanthemum morifolium ‘Bright Golden Anne') were grown at 10 rates of K supply, symptoms of K deficiency were recorded, and the K concentrations in the leaves at harvest were measured. The initial K deficiency symptoms, consisting of glazing and bronzing of the leaf underside, were nearly identical to the injury attributed to the air pollutant, peroxyacetyl nitrate (PAN). Leaves with these symptoms contained 0.5 to 0.6% K. During vegetative growth K deficiency symptoms developed first on the most recently mature leaf; during rapid flower development the symptoms appeared first on the uppermost leaf of the stem. In K‐deficient plants, there was a gradient in K concentration from upper leaves (0.2% K) to lower leaves (1.7% K).  相似文献   

8.
The decomposition of alder ( Alnus glutinosa ) and poplar ( Populus tremula ) leaf litter placed in direct contact with non-polluted and metal-polluted soil was investigated over 25 months in a controlled model-ecosystem experiment using the litterbag method. In addition to mass loss, we monitored the total and soluble concentrations of carbon, Cu, Zn, Cd and Pb. Leaves from trees grown on polluted soil had larger initial Zn, Cd and dissolved organic carbon concentrations. Neither the origin of the leaves (from trees grown on non-polluted or polluted soil) nor the placement of the leaves in polluted or unpolluted soil affected the decomposition process. Total metal contents increased in leaves placed on polluted soil over time. The solubility of metals in the leaf litter decreased over time, indicating that leaves acted as a temporary pool for metals from the soil in direct contact with the leaves. The sorbed metals were strongly bound in the litter even after two years of decomposition. The strong binding and thus reduced bioavailability of the metals provides an explanation for why they had no observable effects on litter decomposition.  相似文献   

9.
Abstract

The effects of blue light supplementation to red light on growth, morphology and N utilization in rice plants (Oryza sativa L. cv. Sasanishiki and Nipponbare) were investigated. Plants were grown under two light quality treatments, red light alone (R) or red light supplemented with blue light (RB; red/blue-light photosynthetic photon flux density [PPFD] ratio was 4/1), at 380 mol m?2 s?1 PPFD. The biomass production of both cultivars grown under RB conditions was higher than that of plants grown under R conditions. This enhancement of biomass production was caused by an increase in the net assimilation rate (NAR). The higher NAR was associated with a higher leaf N content per leaf area at the whole-plant level, which was accompanied by higher contents of the key components of photosynthesis, including Rubisco and chlorophyll. In Sasanishiki, preferential biomass investment in leaf blades and expansion of wider and thinner leaves also contributed to the enhancement of biomass production. These morphological changes in the leaves were not observed in Nipponbare. Both the changes in physiological characteristics, including leaf photosynthesis, and the changes in morphological characteristics, including leaf development, contributed to the enhancement of biomass production under RB conditions, although the extent of these changes differed between the two cultivars.  相似文献   

10.
Watercress (Nasturtium officinale R.Br.) is the richest source of glucosinolate nasturtiin, which on hydrolysis produces phenethyl isothiocyante (PEITC). Interest in growing watercress is stimulated since demonstration of the role of PEITC in protection against cancers associated with tobacco specific carcinogens. Twenty-one days old watercress seedlings were transplanted into growth chambers (16-h days/8-h nights of 25/22 degrees C and photosynthetic photon flux (PPF) of approximately 265 micromol m(-2) s(-)(1)). The study was replicated three times. Leaves were analyzed for PEITC and ascorbic acid concentrations at transplant, and harvested at 10-days intervals until 60 days after transplant. The PEITC and ascorbic acid concentrations were the highest in leaves harvested at 40 days and the lowest at transplant. Leaves harvested at 40 days produced about 150% higher PEITC concentrations compared to the leaves at transplant. Both PEITC and ascorbic acid concentrations of leaves increased linearly with age until 40 days after transplant after which there was no significant increase. Seedlings at transplant had the lowest dry mass and leaf area, while plants harvested at 60 days had the highest dry mass and leaf area.  相似文献   

11.
Mineral deficiencies can seriously reduce crop yield and economic returns to farmers. Reflectance measurements may provide inexpensive and fast estimates of the mineral status of plants. This study was conducted to examine specific changes of leaf reflectance due to nutrient deficiencies. During the 1998 and 1999 growing seasons leaf scans of N‐, P‐, Mg‐, and Fe‐deficient corn plants were performed with a digital LEICA S1 PRO camera under controlled light conditions. Leaf scans were evaluated with the L*a*b*‐color system. This is a three‐dimensional system with parameter a* describing the green/red percentage and parameter b* the blue/yellow percentage of a color. L* represents the lightness of a color. The a* and b* parameters provided good prediction of N, P, Mg, and Fe status of the plants in the wavelength ranges of 380—390 nm, 430—780 nm, 516—780 nm, 516—IR, and 540—600 nm because reflectance changed specifically due to the nutrient deficiency. Analyses of water‐soluble and propanol‐soluble pigments showed no significant changes in absorbance during latent deficiency. The results indicate that reflectance measurements may provide a powerful tool for the specific detection of latent nutrient deficiencies in corn plants.  相似文献   

12.
The aroma in sweet basil is a factor affecting the commercial value of the crop. In previous studies leaf age was considered to be a factor that influences the composition of essential oil (EO). In this study it was hypothesized that a single observation of the EO content in leaves from different positions on the main stem (young vs old) could predict the developmental changes in the plant during its life cycle. Plants harvested at week 16 demonstrated an exponential increase (R(2) = 0.92) in EO concentration in leaves on the main stem and lateral shoots, indicating higher EO concentrations in younger than in older leaves. Eugenol and methyleugenol predominated (28-77%) in the extract. Eugenol levels were higher in younger leaves (～53%), and methyl-eugenol levels predominated in older leaves (～68%). Linalool was lower in mature leaves than in younger leaves. This suggested that eugenol converted into methyleugenol and linalool decreased as leaf mature. However, in weekly monitored plants, the levels of these compounds in the EO had limited variation in the maturing leaf regardless of its position on the stem. This proposed that the EO composition in an individual leaf is mostly affected by the leaf position on the stem and not by its maturation process. Because leaf position is related to plant development, it is probable that the plant's physiological age at the time of leaf formation from the primordial tissue is the factor affecting the EO composition. It was concluded that interpretation of scientific observations should be carried out with caution and that hypotheses should be tested utilizing multifaceted approaches.  相似文献   

13.
《Journal of plant nutrition》2013,36(8):1381-1393
Abstract

Root and leaf ferric chelate reductase (FCR) activity in Annona glabra L. (pond apple), native to subtropical wetland habitats and Annona muricata L. (soursop), native to nonwetland tropical habitats, was determined under iron (Fe)-sufficient and Fe-deficient conditions. One-year-old seedlings of each species were grown with 2, 22.5, or 45 µM Fe in a nutrient solution. The degree of tolerance of Fe deficiency was evaluated by determining root and leaf FCR activity, leaf chlorophyll index, Fe concentration in recently mature leaves, and plant growth. Root FCR activity was generally lower in soursop than in pond apple. Eighty days after plants were put in nutrient solutions, leaf FCR activity of each species was lower in plants grown with low Fe concentrations (2 µM) than in plants grown with high (22.5 or 45 µM) Fe concentrations in the nutrient solution. Leaves of pond apple grown without Fe became chlorotic within 6 weeks. The Fe level in the nutrient solution had no effect on fresh and dry weights of soursop. Lack of Fe decreased the leaf chlorophyll index and Fe concentration in recently matured leaves less in soursop than in pond apple. The rapid development of leaf chlorosis in low Fe conditions and low root and leaf FCR activities of pond apple are probably related to its native origin in wetland areas, where there is sufficient soluble Fe for adequate plant growth and development. The higher leaf FCR activity and slower growth rate of soursop compared to pond apple may explain why soursop did not exhibit leaf chlorosis even under low Fe conditions.  相似文献   

14.
Vaccinium myrtillus L. is a common shrub in the herbaceous layer of pine forests. In connection with resistance to pollution it has been widely used in the environmental monitoring based on heavy metal accumulations in the foliage. The present study investigates leaves of bilberry growing under influence of emissions from a Zn–Pb smelter. Determination of heavy metal levels by AAS revealed enhanced accumulations of Zn, Pb, Cd, and Fe, and the level of Zn fell into the toxic range compiled for plants of average sensitivity. To verify the significance of metal accumulations occurring in the studied plant, the concentrations of phenolics were quantified by measuring UV absorption of foliage extracts. Phenolics can be used as a potential biomarker of pollution because they participate in plant’s response to accumulation of heavy metals, acting as antioxidants able to scavenge free radicals produced by metal ions. Leaves collected near the smelter contained significantly higher amounts of phenolics. Since these compounds are also responsible for ecological interactions, changes in their concentrations resulting from heavy metal accumulations might also influence other organisms in the ecosystem. To study the role of phenolics in heavy metal accumulations at the cellular level, a special fixation was applied for TEM, involving glutaraldehyde with caffeine, to precipitate phenolics in the cell. A histochemical reaction showed significantly higher electron-opacity, most probably deposits of phenolics, in cells of the leaves collected near the smelter. The subsequent degenerative changes in mesophyll of these leaves were characterized by increased contents of heterogeneous multivesicular structures, degeneration of chloroplasts, and disorganisation of membranes leading to death of the cell and necrosis.  相似文献   

15.
Barley is considered a healthy food because of its high content of β‐glucan and phenolic antioxidants. In the current study, 28 black, blue, and yellow barleys were investigated in terms of their composition of free and bound phenolic acids and 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging capacity. Free phenolics were based on aqueous methanol extraction, whereas bound phenolics were extracted following alkaline hydrolysis. Phenolics were then separated and quantified by liquid chromatography and the Folin–Ciocalteu method. Significant differences were observed between the three barley color groups, and within each color group a wide range of phenolics concentrations existed. Ferulic acid was the predominant phenolic acid in free and bound extracts, followed by p‐coumaric acid in all the barleys investigated. Total phenols content and individual phenolic acids strongly correlated with free radical scavenging capacity of barley. Black and blue barley were found to be related and distinct from yellow barley. The results showed significant variations in phenolics among barleys, with a potential for the development of barley grains with high content of phenolic compounds as antioxidant potential.  相似文献   

16.
Abstract

The role of molybdenum in plant growth was examined by growing ‘Emerald’ okra (Abelmoschus esculentus L. Moench) to fruiting in sand‐culture.

Molybdenum treatment lower than 1 ppm, resulted in leaves that were generally pale yellow and curled upwards. At 1 ppm and 4 ppm Mo, plants were generally healthy with deep green leaves, while Mo application at 6 and 16 ppm resulted in stunted plant growth, deep green leaves, and dark brownish coating on the roots. Shoot/root ratio decreased with increasing rates of Mo. Total chlorophyll was unaffected by Mo application, whereas plant dry matter production and fruit yield were depressed at the 16 ppm Mo treatment.

Leaves of plants receiving less than 1 ppm Mo had higher concentrations of NO3‐N, P, K, Ca and Mg than plants receiving above 1 ppm Mo treatments. The reverse was the case with the micronutrient levels. Specifically, Mo treatments higher than 1 ppm increased leaf‐Mo, ‐Fe, Mn and Zn and root‐Mo and Mn. The highest percentage of Fe and Mn, accumulated in the leaves, followed by the root and least in the wood, whereas the roots had the highest percentage of accumulated Mo, Cu and Zn. Leaf‐Mo was positively correlated with leaf‐Fe and Mn and root‐Mo and Mn. Molybdenum deficiency symptoms appeared in plants with leaf‐Mo of 5 ppm and treated with less than 1 ppm Mo. The 2 ppm Mo treatment with leaf‐Mo of 18 ppm produced normal and healthy plants, whereas. Mo application from 8 to 16 ppm with corresponding leaf‐Mo of 42 and 90 ppm Ho respectively produced plants that were severely stunted and had generally poor growth. The relatively high Ho concentration observed suggests that the okra plant is a Mo accumulator.  相似文献   

17.
The objective of the present study was to examine the effect of potassium (K) fertilization and soil texture on total yield (1st and 2nd cuttings) and yield components of sweet basil (Ocimum basilicum L.) A greenhouse pot experiment was conducted in a completely randomized statistical design. Basil growth was examined in two different textured soils under three different doses of K fertilization. Generally, for the basil grown under clay soil conditions, moderate amounts of K fertilization is proposed to be sufficient if higher linalool contents are wanted. However, if the growing conditions are sandy loam in texture, it is suggested that higher doses of K be used. Results also highlighted the contribution of second cut as an important cultural practice in the cultivation of an annual basil.  相似文献   

18.
During growing and flowering seasons for five years, comparisons were made between upper and lower leaf surfaces microflora of ragweed plants grown in three areas: a relatively non-contaminated site, a communal landfill, and a complex contaminated with heavy metals. Results indicated that phyllospheric microbial communities were qualitatively and quantitatively related to metal content in plant leaf, leaf surfaces and metal contaminated ecosystems where the plants grown. Results showed that there was a high positive correlation between phyllospheric microbial population densities and Cd, Ni, and Zn content in ragweed leaves, while it was low in presence of Cu. Comparatively, the correlation was at its highest in the case of aerobic heterotrophic bacterial population densities and more than yeasts and filamentous fungi communities. The most common diversities of metal resistant microorganisms were related to Pantoea agglomerans, Pseudomonas savastanoi, P. putida, Bacillus cereus, Corynebacterium striatum, Cryptococcus and Alternaria.  相似文献   

19.
The main objective of the present work was to clarify the causal relationship between leaf apoplastic pH increase and Fe chlorosis under alkaline growth conditions. It has been shown that nitrate supply in contrast to ammonium supply induced a pH increase in the apoplast of young green leaves of Helianthus annuus which was followed within 12 hours by leaf yellowing. Hence nitrate nutrition is the primary cause of a high leaf apoplastic pH which induces Fe deficiency chlorosis and not the impaired provision of ATP for plasmalemma H+ pumps in yellow leaves. Supply of bicarbonate in physiological concentrations had virtually no influence on leaf apoplastic pH. Spraying leaves with diluted acids (citric acid, sulphuric acid) resulted in a decrease of apoplastic pH followed by leaf re-greening. Interestingly, the Fe concentrations remained the same in the yellow control leaves and in the sprayed green leaves. From this it follows that Fe efficiency in leaves is mainly related to the Fe distribution between apoplast and symplast. It was demonstrated that Fe chlorosis induced by nitrate nutrition begins from the base of the youngest leaves, presumably from growing interveinal microsites showing high nitrate uptake rates. Leaf yellowing spread gradually from the leaf base to the tip and after seven days of nitrate supply the leaf was almost completely yellow (98%). Leaf yellowing was measured by means of a video imaging technique. Leaf apoplastic pH recordings were conducted after loading the fluorescent dye FITC-Dextran (4000 D) into the leaf apoplast of intact plants thus simulating in vivo conditions. It was also shown using the new loading technique that the fluorescent dye did not penetrate the leaf symplast.  相似文献   

20.
Many herbs and spices have been shown to contain high levels of polyphenolic compounds with potent antioxidant properties. In the present study, we explore how nutrient availability, specifically nitrogen fertilization, affects the production of polyphenolic compounds in three cultivars (Dark Opal, Genovese, and Sweet Thai) of the culinary herb, basil ( Ocimum basilicum L.). Nitrogen fertilization was found to have a significant effect on total phenolic levels in Dark Opal ( p < 0.001) and Genovese ( p < 0.001) basil with statistically higher phenolic contents observed when nutrient availability was limited at the lowest (0.1 mM) applied nitrogen treatment. Similarly, basil treated at the lowest nitrogen fertilization level generally contained significantly higher rosmarinic ( p = 0.001) and caffeic ( p = 0.001) acid concentrations than basil treated at other nitrogen levels. Nitrogen fertilization also affected antioxidant activity ( p = 0.002) with basil treated at the highest applied nitrogen level, 5.0 mM, exhibiting lower antioxidant activity than all other nitrogen treatments. The anthocyanin content of Dark Opal basil was not affected by applied nitrogen level, but anthocyanin concentrations were significantly impacted by growing season ( p = 0.001). Basil cultivar was also determined to have a statistically significant effect on total phenolic levels, rosmarinic and caffeic acid concentrations, and antioxidant activities.  相似文献   

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