A. Chronopoulou-Sereli

A note on the evolution of the daily pattern of thermal comfort-related micrometeorological parameters in small urban sites in Athens

Studies on human thermal comfort in urban areas typically quantify and assess the influence of the atmospheric parameters studying the values and their patterns of the selected index or parameter. In this paper, the interpretation tools are the first derivative of the selected parameters (∆Parameter/∆t) and the violin plots. Using these tools, the effect of sites’ configuration on thermal conditions was investigated. Both derivatives and violin plots indicated the ability of vegetation to act as a buffer to the rapid changes of air temperature, mean radiant temperature, and the physiologically equivalent temperature (PET). The study is focused on the “thermal extreme” seasons of winter (December, January, and February) and summer (June, July, and August) during a 3-year period of measurements in five selected sites under calm wind and sunny conditions. According to the results, the absence of vegetation leads to high derivative values whereas the existence of dense vegetation tends to keep the parameters’ values relatively low, especially under hot weather conditions.

AIR TEMPERATURE AND THERMAL COMFORT CONDITIONS IN MOUNTAINOUS AND URBAN REGIONS

The present study explored air temperature and thermal comfort conditions in mountainous region of Nafpaktia (Municipality of Apodotia, Prefecture of Aitoloakarnania), a region without important commercial, industrial or other activities in west continental Greece, and in Athens, a metropolitan urban center in southeast continental Greece. There were 11 study sites in the case of Nafpaktia (676–1455 m altitude), areas with different altitude, ground cover, plant species and plant density. There was one study site in Athens (30 m altitude) nearby a densely built area, under the pressure of industrial activities and heavy traffic. Air temperature and humidity, 1.5 m above ground surface, were monitored simultaneously every 15 min in each site for the period between 1 July and 31 August 2006. Air temperature and relative humidity data were used for the calculation of the thermohygrometric index (THI) from which thermal comfort conditions were evaluated. For this work, two sites of mountainous Nafpaktia region (MNR), one characterized by the lower (fir and chestnut forest area) and the other by the higher (Evinos River area) average THI value, are presented. Results showed that MNR provided clearly improved air temperature and thermal comfort conditions in comparison to Athens in the study period. Fir and chestnut forest area was more beneficial, from a bioclimatological point of view, compared to Evinos River area. Therefore, fir and chestnut forest area should be further supported as a reliable alternative tourist destination for rest and recreation.

Specific Leaf Area and Leaf Nitrogen Concentration of Lantana in Response to Light Regime and Triazole Treatment

Abstract The paclobutrazol (0, 50, 100, 200, and 500 mg L−1) and triapenthenol (175, 350, 700, and 1400 mg L−1) effects on specific leaf area (SLA) and leaf nitrogen (LN) concentration of Lantana camara L. (subsp. camara) under the shading levels 0%, 27%, and 66% were determined in glasshouse experiments. In most cases, increased concentrations of paclobutrazol and triapenthenol decreased SLA and increased LN of plants logarithmically at all shading levels. The SLA, at all concentrations examined, was generally increased with increased shading; LN showed an increase at 66% shading compared to 0% shading in the case of triapenthenol. The SLA reduction of paclobutrazol‐treated plants in relation to untreated plants of the same shading level was 18% to 37%; reduction was 49% to 73% for plants treated with triapenthenol at 0% shading, indicating a greater effect of triapenthenol on SLA reduction than paclobutrazol at previous shading.

Environmental conditions and drenched-applied paclobutrazol effects on lantana specific leaf area and N, P, K, and Mg content

Lantana camara L. is used extensively in many countries as an ornamental plant species but limited information is provided about the fertilization of this plant, especially after treatments with the triazole paclobutrazol (PBZ). The effects of drenched-applied PBZ at concentrations of 0, 40, and 80 mg L-1 on specific leaf area (SLA) and leaf N, P, K, and Mg concentrations of L. camara L. subsp. camara (lantana) plants were examined under different environmental conditions, resulted from different shading levels, 0% (daily light quantity of 27.8 mol m-2 d-1) and 66% (9.4 mol m-2 d-1) in glasshouse experiments in Attica, Greece. The concentration of leaf N was affected by the PBZ treatment (P < 0.01), while the shading level affected K and Mg concentration (P < 0.01). Plants treated with the same PBZ concentration presented higher SLA with 66% shading compared to 0% shading. The more the PBZ concentration, the lower and the higher were the SLA and leaf N respectively, at both shading levels. Leaf P, in general, increased with increasing PBZ concentration and shading as did K and Mg at 66% shading compared to 0% shading. At the end of the experiment all plants were healthy with no visible symptoms of nutritional deficiency. The findings of our study could be useful in establishing a fertilization program for L. camara plants treated with different drenched-applied PBZ concentrations under various environments.

Biometeorological Conditions in the Urban Park of Nea Smirni in the Greater Region of Athens, Greece During Summer

The aim of this study was to investigate the biometeorological environment in relation with different types of ground cover in the urban park area of Nea Smirni in the greater region of Athens in Greece. Five sites were selected, including irrigated (IPS) and non irrigated plant species (NIPS) and the adjacent build-up area (ABA). The thermal condition of the environment around the examined sites was evaluated using an infrared thermografic camera in the summer of the years 2009–2011. Also, data loggers with temperature and humidity sensors were placed in the aforementioned sites during the experimental period. Results showed that the environment of NIPS appeared, in general, to have a warmer trees foliage in relation to IPS by about 2°C. Higher surface temperature conditions were detected in sites covered with structural materials. On the other hand, lower temperature conditions were observed in the shaded sites and in the water surfaces. For the period between 11:00 and 19:00 h, more favorable human thermal comfort conditions among the examined types of ground cover, as were evaluated by the thermohygrometric index, were observed at the environment with IPS, especially in July, rendering the aforementioned environment more friendly to the visitors.

An investigation of the effects of environmental factors on Lantana camara L. subsp. camara responses to paclobutrazol and mepiquat chloride

Summary Potted plants of Lantana camara L. subsp. camara were sprayed with paclobutrazol (0, 50, 100, 200 and 500 mg l–1) and mepiquat chloride (125, 250, 500 and 1000 mg l–1) and their growth and flowering were determined under shading (0%, 27% and 66%) under greenhouse conditions. Growth (measured as a growth index combining height and width data) was found to decrease as paclobutrazol concentration increased while the number of flower heads per plant increased up to a maximum at the concentration of 100.mg l–1 with a decrease afterwards, at all shading levels. The growth index of the controls increased and the number of flower heads per plant decreased significantly at all concentration levels, as shading increased from 0% to 66%. The treatments with mepiquat chloride increased the growth index at all levels of shading. All plants treated with this regulator had more flower heads than the controls. At all concentration levels the growth index increased as shading increased from 0% to 66% while the number of flower heads was increased at 27% shading with a decrease afterwards. The most attractive plants (small with maximum flowering) were obtained with 100 mg l–1 paclobutrazol at 0% shading.

Bioclimatic Conditions in Relation to Shading in a Glasshouse: The Case Study of Lantana Camara L. Cultivation in Summer

In a previous work, Lantana camara L. (lantana) plants grew in three different light environments after treatments with drenched-applied paclobutrazol to test their potential to give easthetically attractive products (small plants with increased flowering). Nevertheless, no information is known with regard to the bioclimatic conditions of the aforementioned light environments (0%, 28% and 66% shadings). Therefore, the present work determined their bioclimatic conditions in summer (hot period of the year) and especially August, with the use of a widely used index, the thermohygrometric index, in a glasshouse in Attica, Greece. Average thermohygrometric index values were used for the evaluation of bioclimatic conditions and the relative frequencies of the different classes of thermohygrometric index were calculated on a two-hour basis for each examined shading. From the results of this study, the environment with the full light regime (0% shading) provided less favorable bioclimatic conditions compared to other examined light regimes (28% and 66% shadings), during the daytime period (08:00-20:00 h). Between 28% and 66% shadings, more favorable bioclimatic conditions were established at 66% shading for the same period. The nighttime period (22:00-06:00 h) was characterized as more friendly, bioclimatically, compared to the respective daytime period, irrespective of the examined light regime. Among the three studied shadings in nighttime period, the more favorable bioclimatic conditions were noticed in the low light regime (66% shading). The less favorable bioclimatic conditions were detected at the plot with 28% shading, compared to other shadings at the aforementioned period. The findings of this study could be beneficial for the planning of the work in other plant cultivations inside a glasshouse the hot period of the year.

Micronutrient Content in Relation to Specific Leaf Area, Light Regime and Drenched-Applied Paclobutrazol in Lantana Camara L.

Iron and manganese are essential microelements on plant growth but no information is known with regard to their content on Lantana camara L. subsp. camara (lantana) treated with drenchedapplied paclobutrazol. Thus, the effects of drenched-applied paclobutrazol [0 (control), 40, and 80 mg l-1] on leaf iron and manganese contents of lantana plants were investigated testing two light regimes, resulted from the establishment of different shading levels, 0% (daily light quantity of 27.8 mol m-2 d-1) and 66% (9.4 mol m-2 d-1) in a glasshouse in Attica, Greece. Possible correlations between the studied minerals contents (iron and manganese) and specific leaf area were examined. Analysis of variance showed that iron and manganese contents were affected by shading level, paclobutrazol, their interaction and paclobutrazol, respectively. Iron content increased significantly after treatments with paclobutrazol, compared to control, at full light environment (0% shading). Leaf manganese content presented no significant increase with the increasing paclobutrazol concentrations at 0% and 66% shadings. No significant differences were noted (dispensing control plants) on iron and manganese contents, when examining plants which were treated with the same paclobutrazol concentration, between the studied light environments. From the linear correlation analysis, manganese content exhibited a significant negative correlation with specific leaf area which was not shown by the iron content. The results of the present study could contribute to establishing iron and manganese sufficiency ranges on L. camara, especially after treatments with different light environments and paclobutrazol concentrations.

Phenological Response of Pear and Orange Trees to Air Temperature at Regions of Thessaly and Peloponnesus, Greece

This research assessed the phenological response of pear (Pyrus communis L. cv. Krystalli) and of orange (Citrus sinensis L. cv. Washington Navel) trees to air temperature at the regions of Kato Lechonia in Thessaly and at Agiorgitika, Ligourio and Amycles in Peloponnesus, Greece. Phenological observations took place in order to evaluate the start dates of various phenophases of the studied cultivars, from the “end of bud swelling” to the “fruit development” stages. Also, air temperature data were monitored from meteorological stations located near the experimental orchards. The results showed that the warmer conditions at Kato Lechonia in comparison with those of Agiorgitika caused an earlier appearance of pear tree phenophases. The timing of the “end of bud swelling” at Kato Lechonia and Agiorgitika correlated negatively with the air temperature of the late winter (February) as did the timing of “bud burst” and of “appearance of flower buds” at Kato Lechonia. As regards to the orange tree, similar phenological behavior during the examined period was observed between the regions of Ligourio and Amycles due to their “similar” thermal conditions.