Effect of the light intensity on forcing of the strawberry cultivar ‘Glasa’

Plants of ‘Glasa’ were forced early in growth rooms at 14°C under a 16-hour day consisting of 8 hours of mercury light, light intensities 12, 24 or 36 W m^?2, supplemented by 8 hours of incandescent light, intensity 0.8 W m^?2. Light intensity affected the flowering-date, the number of inflorescences, the number of flowers per inflorescence, stamen development and fruit set. For successful forcing, a light intensity of at least 24 W m^?2 is necessary.     

City–forest relationship in Nagpur: One of the greenest cities of India

There are sporadic reports on urban forests in Indian cities. Nagpur is one of the greenest cities of India with 18 per cent of its area under forests and plantations, 17 per cent under cultivation and 2 per cent under water bodies. The present study showed that natural vegetation of the city is very well diversified with a representation of 59 per cent vegetation including 124 trees species belonging to 38 families as compared with the overall district vegetation statistics. Air quality in the city is relatively better with lower SO₂ (6 μg/m³), NO₂ (18 μg/m³) and Respirable Suspended Particulate Matters (RSPM, 53 μg/m³) as against National Ambient Air Quality Standards (2009) for cities in India of 80, 80 and 100 μg/m³, respectively. It was also noted that the diversity in natural forests which are being protected is greater than the plantations undertaken by the civic authorities and private sector efforts. The study thus demonstrated the positive relationship of the city with diversified vegetation cover for cleaner environment. The analysis is expected to guide formulation of strategies for maintaining green space in the city.     

Comparison of Freeze Protection Methods for Strawberry Production in Florida

During strawberry (Fragaria × ananassa) freeze protection, the standard practice is applying sprinkler irrigation on plant canopies to prevent and reduce freezing damage. This method is highly inefficient because it uses large volumes of water. The overall goal of this study was to compare the effects of freeze protection methods on water savings, and growth and fruit weight of strawberry. Treatments consisted of the following: sprinkler heads delivering 17 L?min^–1, sprinkler heads delivering 13 L?min^–1, light-weight row covers (21 g?m^–2) on the crop canopy, light-weight row covers on 60-cm-high mini-tunnel hoops, heavy-weight row covers (31 g?m^–2) on the crop canopy, heavy-weight row covers on 60-cm-high mini-tunnel hoops, and foliar application of a polymer (Desikote). There were eight freezing and near freezing nights (≤1.1 °C) at the experimental site during both seasons with a minimum air temperature of –2.8 °C. Minimum temperature inside the row covers ranged between 0.6 to 4.4 °C at the canopy level. There were significant treatment effects on early and total marketable fruit weights. The highest early marketable fruit weight was found in plots protected with light-weight row covers with hoops, heavy-weight row covers on canopy, and foliar polymer, ranging between 5.0 to 5.5 t?ha^–1. For total marketable fruit weight, using non-irrigation methods resulted in the highest fruit weight with 23.0 t?ha^–1. In conclusion, data showed that using non-irrigation techniques provided satisfactory freeze protection under the evaluated conditions and increased total marketable fruit weight, possibly due to reduced injury of fruits and flowers when using alternative techniques.     

Growth and cation accumulation in spray carnations

Spray carnations (Dianthus caryophyllus ‘Exquisite’), planted as potted cuttings in December, had a maximum dry-matter production in summer of 22 g m^?2 day^?1, calculated for the net surface area completely covered by the crop. This value is fairly similar to the maxima established for outdoor crops in The Netherlands.The cation contents in the whole plant, expressed as percentages of dry matter, followed the series Na < Mg < Ca < K. They displayed no significant deviations from what was found in the literature for perpetual-flowering carnations. Growth was slow in the early phase of the crop and the cation accumulation was correspondingly slight. Growth increased at about 3 months after planting out. Over the period from March to September (24 weeks), the contents established in the aerial parts of the spray carnations amounted to 0.2 kg Na, 6.2 kg K, 2.9 kg Ca and 0.6 kg Mg per 100 m² gross.     

Untangling the positive and negative effects of shrubs on herbaceous vegetation in drylands

Woody vegetation, as an ecosystem engineer, can modulate the landscape such that the levels of resources in its vicinity undergo positive and negative changes as far as the herbaceous vegetation is concerned. To better understand how these processes play out in a semi-arid ecosystem, we examined resource modulation by woody vegetation, and the response of herbaceous vegetation to that modulation, at a fine spatial scale. Experimental manipulations were employed to separate the positive and negative effects of water, light and seed dispersal in determining herbaceous species density and biomass in three patch types within and adjacent to the shrub (core, periphery and open). We synthesized our results into a multilayered landscape diversity (MLLD) model. Woody vegetation creates distinct multilayered resource patches at its core and periphery which do not correspond to the dichotomous structural pattern of shrub canopy versus intershrub background. The combined effect of these multilayered resource patches had higher herbaceous species density (8.2 vs. 4.0 species 400?cm^?2) and herbaceous biomass (5.4 vs. 1.0?g 400?cm^?2) in the periphery than in the core (3-yr averages). The periphery??s net positive effects are due to enhancement of soil properties (water infiltration depth of 11.1?cm at periphery vs. 8.1?cm at core), while the core??s net negative effects are due to modulation of seed (seed abundance per seed trap of 44.2 at periphery vs. 3.0 at core) and light availability (PAR transmittance of 41.9?% at periphery vs. 16.5?% at core) by the shrub canopy. Thus, when examined at this fine spatial resolution, woody vegetation has both net positive and net negative effects on herbaceous vegetation. Analysis of our results by means of the MLLD model emphasizes the importance of examining the landscape at the spatial scale of the modulated resources and of recognizing different patch types and their differing effects on herbaceous vegetation.     

Effect of temperature and irradiance on vegetative and generative development in Pelargonium × hortorum ‘Radio’

Vegetatively propagated plants of Pelargonium × hortorum ‘Radio’ were grown at 8 combinations of irradiance and temperature levels; 4 or 22 W m^?2 combined with 12, 15, 18 or 21°C. Increase in leaf number, leaf area, shoot and number of inflorescences per plant were all greater at 22 W m^?2 than at 4 W m^?2. At 22 W m^?2, increase in temperature affected leaf number, leaf area and shoot number, but not inflorescence number. However, at 4 W m^?2, number of inflorescences — but not leaf or shoot number — was affected by temperature. When effects of temperature differences were observed, the highest temperature resulted in the greatest number of leaves and shoots and the largest leaf area, but the lowest number of inflorescences per plant. The results indicate that photosynthesis or energy metabolism is of importance to floral initiation in Pelargonium × hortorum.     

Private residential urban forest structure and carbon storage in a moderate-sized urban area in the Midwest,United States

In conjunction with urbanization and its importance as a major driver of land-use change, increased efforts have been placed on understanding urban forests and the provisioning of ecosystem services. However, very little research has been conducted on private property and little is known about the structure and function of privately owned urban forests. This research examines the structure of and carbon storage services provided by private residential urban forests in a moderate-sized Midwestern city. The primary research questions are as follows: What is the structure of private urban forests, and how does it vary across parcels? How much carbon is stored in tree and soil pools of private urban forests, and how does carbon vary across parcels? Ecological inventories were conducted on 100 residential parcels within 14 Neighborhood and Homeowners Associations of varying size and development age. Tree species richness, diversity, density, and diameter distribution were determined on a per parcel basis and for the entire tree population sampled. Further, tree and soil carbon storage were determined for each parcel. Results of this research demonstrated large variability in per-parcel tree metrics. Twelve of the parcels sampled had two or fewer trees, while eleven had greater than 50 trees. Further, tree carbon storage ranged from no carbon to 11.22 kg C m^?2. Alternatively, soil carbon storage was less variable and averaged 4.7 kg C m^?2, approximately 1.9 times higher than the average carbon stored in trees (2.5 kg C m^?2). Management efforts aimed at maintaining or enhancing carbon storage and other ecosystem services should focus on both soil protection and maximizing services in living biomass. Our results demonstrate that sustaining tree-produced ecosystem services requires maintenance of large old trees and species diversity, not only in terms of relative abundance, but also relative dominance, and in combination, species–specific size distributions.     

Effects of Iron Sulfate,Zinc Sulfate,Iron Chelate,Powder Sulphur and Humic Acid Applications on Vegetative Growth of Sweet Cherry (<Emphasis Type="Italic">Prunus avium</Emphasis> L.)

This study was carried out in ?scehisar district of Afyonkarahisar on ‘0900-Ziraat’ sweet cherry cultivar for two successive years in 2011 and 2012. Ten different applications consisting of 80?g FeSO₄.7H₂O tree^?1, 20?g FeEDDHA tree^?1, 420?mL TK?-Hümas tree^?1, 80?g FeSO₄.7H₂O + 420?mL TK?-Hümas tree^?1, 200?g powder sulphur (S) tree^?1, 80?g FeSO₄.7H₂O + 200?g powder S tree^?1, 25?g ZnSO₄.7H₂O tree^?1, 25?g ZnSO₄.7H₂O + 420?mL TK?-Hümas tree^?1 and 25?g ZnSO₄.7H₂O + 200?g powder S tree^?1 were subjected for determination of their effect on vegetative growth of sweet cherry. In this study, shoot diameter, shoot length, leaf total chlorophyll content, leaf area and leaf iron (Fe) and zinc (Zn) contents were obtained. Shoot length, shoot diameter and leaf area showed general increases in 80?g FeSO₄.7H₂O + 200?g powder S tree^?1 and 25?g ZnSO₄.7H₂O + 200?g powder S tree^?1 treatments.The results clearly indicated that he treatments had different effects on the shoot length and shoot diameter although there was a differences between the experimental years. Particularly, significantly positive effects of the treatments on leaf total chlorophyll was apparent for the second year’s observations. In addition, Fe and Zn concentrations in leaf were markedly increased in response to the treatments.     

The effect of nitrogen,volume of media,plant density and module shape on the growth of asparagus seedlings

There were three experiments in which the seedlings were raised in media contained in plastic cells. In Experiment 1, 150 or 200 mg l^?1 N were applied in factorial combination with cell volumes of 20, 32 or 50 cm³, There were 6 successional harvests. All cells were 7.5 cm deep and cylindrical in shape. Experiment 2 compared these 3 cell volumes at densities of 983, 1532 or 2440 plants per m². Cell diameters restricted the 50-cm³ cell to the 983, and the 32-cm³ cell to the 983 and 1532 plants per m² densities. 200 mg l^?1 N increased shoot growth, but not root growth. This increase in shoot growth was not considered advantageous. Seedling growth increased with increases in cell volume, but there were no responses to changes in plant density. Experiment 3 compared a cell having an inverted pyramid shape with a cylinder. The cylinder, despite holding 20% less media, produced the larger seedlings.     

Effect of temperature on photosynthesis of lettuce adapted to different light and temperature conditions

Gas exchange of lettuce plants, pre-grown in growth chambers at different irradiances (18, 37, 70 W m^?2) and temperatures (6, 14, 22°C) were measured in the range of 2–22°C. In weak light (18 W m^?2) there was no increase in CO₂ uptake above 2°C, and even in 70 W m^?2 the highest rates were obtained at about 10°C only. The response of net photosynthesis of lettuce to temperature is diminished as a result of morphological plant adaptations, i.e. specific leaf area or top-to-root weight ratio. The temperature optimum for dry-matter production is much higher than that for CO₂ uptake. Therefore, photosynthesis is an unsuitable criterion for temperature control in greenhouses.     

Nitrogen and irradiance levels affecting net photosynthesis and growth of young coffee plants (Coffea arabica L.)

Summary

Shoot growth attributes, leaf anatomical changes and net photosynthetic rates were determined in young coffee plants fertilized at high and low levels and subjected to shade or full sunlight. High nitrogen supply increased plant height irrespective of the light level imposed during growth, and promoted a larger leaf area in plants of the shade treatment. Specific leaf weight was 15% higher in plants grown in full sunlight than in shaded plants, at both nitrogen levels. The number of leaves developed on the orthotropic stem increased significantly under full irradiance and high nitrogen availability. Leaves were 11% thicker ih unshaded plants than in shaded ones, because of the increased size of the palisade and spongy parenchyma tissues. More thylakoids per granum and more grana per chloroplast were observed in shade-grown plants, mainly in those given high nitrogen treatment. Total nitrogen content expressed on a leaf-area basis was higher in sun plants supplemented with nitrogen, whereas chlorophyll a and b and protochlorophyll contents increased in shade-grown plants. Net photosynthetic rate in high nitrogen plants reached 7.19 µmol CO₂ m^?2 s^?1 in the full irradiance treatment, and 5.46 µmol CO₂ m^?2 s^?1 in shaded plants. Maximum net photosynthetic rates in the low nitrogen plants were 5.28 and 4.90 µmol CO₂ m^?2 s^?1 in sun and shade plants, respectively. Increased photosynthetic light saturation was observed in high irradiance plants (628 µmol m^?2 s^?1) relative to shade plants (359 µmol m^?2 s^?1) in the high nitrogen treatment. The same pattern was observed in low nitrogen plants. The apparent quantum yield of shade acclimated plants was 14% higher than in those grown in full sunlight. Our results indicate that coffee may be classified as a facultative shade species, exhibiting features of sun adapted plants coupled with shade acclimation attributes, this fairly high adaptive capacity to shade:sun transition being strongly influenced by the level of nitrogen nutrition given to the plants.     

越橘早熟新品种‘徽王2号’

‘徽王2号’是从北高丛越橘‘布里吉塔’早熟芽变中选育出的新品种。平均单果质量2.26 g,果实扁圆形,果形指数0.71,可溶性固形物含量11.40%,有机酸含量3.18%,维生素C含量46.70 mg ? kg-1,花青素含量49.51 mg ? kg-1,盛果期产量18 t ? hm-2。在安徽省沿江地区,果实6月上中旬开始采收。     

High carbon losses from established growing sites delay the carbon sequestration benefits of street tree plantings – A case study in Helsinki,Finland

We assessed the net carbon (C) sequestration dynamics of street tree plantings based on 10 years of measurements at two case study sites each with different tree species in Helsinki, Finland. We assessed C loss from tree soils and tree C accumulation, tested the applicability of pre-existing growth and biomass equations against observations, and estimated the time point for the beginning of net C sequestration for the studied street tree plantings. The tree woody biomass C accumulation in the first 10 years after planting was 18–32 kg per tree. At the same time the C loss from the growth media was at least 170 kg per growth media volume (25 m³) per tree. If this soil C loss was accounted for, the net C sequestration would begin, at best, approximately 30 years after planting. Biomass equations developed for traditional forests predicted more stem biomass and less leaf and branch biomass than measured for the species examined, but total aboveground biomass was generally well predicted.     

Linear downscaling from MODIS to landsat: connecting landscape composition with ecosystem functions

Context

The open and free access to Landsat and MODIS products have greatly promoted scientific investigations on spatiotemporal change in land mosaics and ecosystem functions at landscape to regional scales. Unfortunately, there is a major mismatch in spatial resolution between MODIS products at coarser resolution (≥?250 m) and landscape structure based on classified Landsat scenes at finer resolution (30 m).

Objectives

Based on practical needs for downscaling popular MODIS products at 500 m resolution to match classified land cover at Landsat 30 m resolution, we proposed an innovative modelling approach so that landscape structure and ecosystem functions can be directly studied for their interconnections. As a proof-of-concept of our downscaling approach, we selected the watershed of the Kalamazoo River in southwestern Michigan, USA as the testbed.

Methods

MODIS products for three fundamental variables of ecosystem function are downscaled to ensure the approach can be extrapolated to multiple functional measurements. They are blue-sky albedo (0–1), evapotranspiration (ET, mm), and gross primary production (GPP, Mg C ha^?1 year^?1). An object-oriented classification of Landsat images in 2011 was processed to generate a land cover map for landscape structure. The downscaling model was tested for the five Level IV ecoregions within the watershed.

Results

We achieved satisfactory downscaling models for albedo, ET, and GPP for all five ecoregions. The adjusted R² was?>?0.995 for albedo, 0.915–0.997 for ET, and 0.902–0.962 for GPP. The estimated albedo, ET, and GPP values appear different in the region. The estimated albedo was the lowest for water (0.076–0.107) and the highest for cropland (0.166–0.172). Estimated ET was the highest for the built-up cover type (525.6–687.1 mm) and the lowest for forest (209.7–459.7 mm). The estimated GPP was the highest for the build-up cover type (8.65–9.85 Mg C ha^?1 year^?1) and the lowest for forest.

Conclusions

Estimated values for albedo, ET, and GPP appear reasonable for their ranges in the Kalamazoo River region and are consistent with values reported in the literature. Despite these promising results, the downscaling approach relies on strong assumptions and can carry substantial uncertainty. It is only valid at a spatial scale where similar climate, soil, and landforms exist (i.e., values in isolated patches of the same cover type are similar). Plausibly, the uncertainties associated with each estimation, as well as the model residuals, can be explored for other pattern-process relationships within the landscape.

     

Acclimatization of Codiaeum variegatum L. ‘Aucubaefolia’ to changes in photon flux density. II. Net photosynthesis,dark respiration and chlorophyll content

Summary

Net photosynthesis, dark respiration and chlorophyll content were studied in plants of Codiaeum when transferred” from a glasshouse to photon flux densities 6, 18, or 66 μE m^?2s^?1 in growth rooms. The diurnal patterns of daily net photosynthesis and dark respiration were recorded during the first 12 days and 3, 7, 11 and 19 weeks after the transfer. Only plants transferred to 66 μE m^?2s^?1 reached a positive total net photosynthesis per day within the first 12 days. This was achieved only between the 12th day and 3 weeks when transferred to 6 μE m^?2s^?1. The rate of net photosynthesis increased until the 11th week and then declined, while dark respiration decreased until the 11th week and then increased. The diurnal patterns of net photosynthesis and dark respiration changed significantly with time of acclimatization. The rate of change in daily net photosynthesis and dark respiration was highest in the plants transferred to the lowest photon flux density. Changes in chlorophyll content of the leaves were similar to those in net photosynthesis.     

The influence of irradiance and external CO2-concentration on photosynthesis of different tomato genotypes

With 4 genotypes of tomato, irradiance and CO₂-response curves of net photosynthesis were analysed by means of curve fitting. Estimated values of the light compensation point I_c showed small but significant differences between the genotypes, the overall value being in the order of 8 W m^?2. The photochemical efficiency (α_n) and the maximum net photosynthesis per unit leaf area basis (P_nm) reached the highest values for ‘F6 IVT’ (13.3 μg CO₂ J^?1 resp. 0.549 mg CO₂ m^?2 s^?1), the lowest value of α_n with ‘Bonabel’ (9.9 μg CO₂ J^?1), and the lowest value of P_nm with ‘PI 114969’ (0.424 mg CO₂ m^?2 s^?1). The CO₂-compensation point (C_c) was relatively high (177–245 mg m^?3). ‘F6 IVT’ demonstrated the highest value of C_c, the lowest carboxylation efficiency and the highest maximum rate of net photosynthesis. The results clearly demonstrate that the latter genotype requires a much higher external CO₂-concentration than the other genotypes in order to exhibit the highest rate of net photosynthesis.     

Influence of BAP Concentrations and Nutrient Medium Composition on <Emphasis Type="Italic">In Vitro</Emphasis> Regeneration of ‘Öküzgözü’ and ‘Boğazkere’ (<Emphasis Type="Italic">Vitis vinifera</Emphasis> L.) Cultivars

This study has been conducted with the aim to determine the type of nutrient medium that can be used in micropropagation studies for ‘Öküzgözü’ and ‘Bo?azkere’ and to specify BAP concentrations. In the study where ejectors with a length of 0.7–0.8?cm that are obtained with single-node culture are used, it was focused on four different nutrient media such as MS, DKW, QL and WPM and on six different concentrations such as 0.2–0.4–0.6–0.8–1.0–1.5 mg l^?1 BAP. Single-node suspension explants which will be used in initiating the culture, are taken into culture in MS nutrient medium and the nutrient medium is supported with 30?g l^?1 sucrose, 6?g l^?1 agar and 1?mg l^?1 BAP. In the trial environment, parameters such as number of shoots, shoot length (cm), number of nodes and callus ratio have been investigated. For both grape varieties, the best outcome was obtained with MS nutrient medium with respect to number of shoots, shoot length, and number of nodes. These values were found as 4.66, 1.24 and 6.39 for ‘Öküzgözü’ variety respectively, whereas they are determined as 6.28, 1.15 and 6.81 for ‘Bo?azkere’ variety respectively. In both grape varieties in DKW nutrient medium, starting from the 2nd week of culture, obscuration began to appear on the shoots and after this stage no other development has taken place.     

Plant spacing studies with processing peas in Ontario,Canada

The reciprocal yield/density equation $\text{1}\text{w}\text{= α + β?}$ (when w is the mean weight per plant, or plant part, at density ?, and α and β are constants when ? is the only variable) was used to interpret the results of two plant density experiments with populations ranging from 15–280 plants/m². In a fertilizer experiment the level of fertilizer used had a major effect on the β parameter, while the α parameter was influenced mainly by harvest date. In a cultivar/rectangularity experiment no effect of rectangularity was detected, and the cultivar mainly affected the α parameter, the β parameter being not significantly different between cultivars. Density was shown to have a major effect on the yield/tenderometer relationship. Yields in excess of 9.9 tonnes/ha (8 800 lb/acre) at a tenderometer reading of 120 (T₁₂₀) were obtained.     

The influence of temperature on photosynthesis of different tomato genotypes

Net photosynthesis and dark respiration from whole plants of various tomato genotypes were measured in a closed system. At low irradiance (27 W m^?2) and low external CO₂ concentration (550 mg m^?3), net photosynthesis of 10 genotypes was found to vary between 0.122 and 0.209 mg CO₂ m^?2 s^?1. Correlation was observed between net photosynthesis, net uptake on a daily basis (8 h photoperiod at 20°C and 16 h nyctoperiod at 10°C), specific leaf weight and leaf area ratio. At high irradiance (243 W m^?2), high external CO₂ concentration (1480 mg m^?3) and ambient temperatures of 10, 18, 20 and 26°C, four genotypes were analysed. ‘F6 I.V.T.’ had the highest rate of photosynthesis at 10°C, while ‘Sonatine’ ranked high at 26°C. Dark respiration increased with temperature, except in the case of ‘Bonabel’ where the effect of temperature was slight.     

Holzhäcksel- und Miscanthusmulch erhalten die Bodenfeuchte und fördern die biologische Bodenaktivität sowie vegetatives und generatives Wachstum junger Apfelbäume

Tree rows of a two-year-old apple (cv. ‘Topaz’) orchard in Klein-Altendorf near Bonn, Germany, were mulched with either a) shredded broadleaf tree trunks (5?cm; 29?t dm/ha) in January 2005, b) high (6?cm; 17?t?dm/ha), or c) low (3?cm, 7?t dm/ha) shredded stems of Miscanthus in July 2004 to conserve resources and achieve closed systems; uncovered soil served as control. The following results were obtained in this MSc thesis during the 2005 growing season:

1. Soil covered with any of the three mulches mineralised 7–14?kg less nitrogen per hectare throughout the growing season resulting in a more balanced nitrogen mineralisation. The reduction in nitrogen supply prevented late vegetative growth and contributed to good fruit colouration.
2. The largest soil respiration was recorded with wooden chips as mulch with a peak of 1.6?CO₂?m^–2?h^{– 1} in June/July, followed by Miscanthus mulch and the uncovered control, which indicates enhanced microbial activity in the summer as a result of medium C/N ratio, warming and better aeration of the wood chips.
3. The organic mulches preserved soil moisture with values of less than 53 centibars and with less fluctuation than in the control.
4. The organic mulches reflected ca. 10% of incident PAR 1?m above ground, i.e. more light than uncovered soil, all without affecting fruit colouration.
5. The two thicker (5?cm and 6?cm) organic mulches suppressed weed population by 63–67% relative to the control.
6. The two thicker (5–6?cm) organic mulches improved potassium uptake by the apple leaves with 1.5 % K relative to 1.3 % K in the control on a leaf dry matter basis, but reduced their calcium and magnesium content.
7. Wood chips as mulch improved vegetative growth of the apple trees during the growing season, measured as trunk diameter, of 4?mm, followed by 3.6?mm of the high Miscanthus and 2.8?mm in both the low Miscanthus mulch and the control.
8. The organic mulches enlarged apple fruit diameter from 78?mm in the control to 80?mm with a concomitant increase in fruit weight from 180?g in the control to 185–188?g.