Nikolaos Ntoulas

Semi-extensive green roof substrate type and depth effects on Zoysia matrella ‘Zeon’ growth and drought tolerance under different irrigation regimes

Abstract Turfgrass use in semi-extensive green roofs might provide an additional solution for establishing green roofs in urban city centres. The aim of the present study was: (a) to investigate the effects of two extensive green roof substrates formulated from mixing locally available materials with two different organic amendments (peat and locally produced compost) in volumetric proportions as indicated by their subscripts S15:Pum40:Per20:P20:Z5, and S15:Pum40:Per20:C20:Z5 (where S = sandy loam soil, Pum = pumice, Per = perlite, P = peat, Z = zeolite and C = compost), and two substrate depths (7.5 cm or 15 cm) on the growth of Zoysia matrella ‘Zeon’; and (b) to evaluate the effect of various substrate types and depths on the drought tolerance of Z. matrella under two irrigation regimes (3 mm or 6 mm of irrigation every 3 days). The measurements included the determination: (a) of substrate characteristics, and (b) both turfgrass quality and physiological status as indicated by the green turf cover (GTC), normalized difference vegetative index (NDVI) and stomatal resistance. It was found that during the establishment and growth period, the compost-amended substrate improved the GTC compared with those amended with peat. In contrast substrate S15:Pum40:Per20:P20:Z5 improved the drought tolerance of Z. matrella during the drought period compared with the compost-amended substrate. Deeper profiles improved the establishment, growth and drought tolerance of turfgrass compared with the shallower profiles. All three factors (substrate type and depth and irrigation regimes) proved to be influential for turfgrass growth and quality during the drought stress period. During the drought period, the GTC and NDVI were higher and stomatal resistance was lower for the peat-amended substrate, the deeper profiles (15 cm) and the higher irrigation regime (6 mm every 3 days).

Soil texture and salinity effects on calibration of TDR300 dielectric moisture sensor

Newly developed sensors have simplified real-time determination of soil water content (θm). Although the TDR300 is one of the most recent dielectric sensors, little is known with regard to the accuracy and dependency of its measurements of soil type and other environmental factors. In this study, the performance of TDR300 was investigated using liquids of known dielectric properties and a set of porous media with textures ranging from sandy to clayey. The experiments were conducted in the laboratory by mixing different amounts of water with each soil to obtain a sufficient range of soil water contents. For sand, the calculated permittivity values (er) correlated adequately with Topp’s equation derived for time domain reflectometry. However, for the remaining inorganic porous media, er values were overestimated compared with those resulting from Topp’s equation, especially for water contents exceeding 0.2 cm3/cm3. The results suggested that the relationship between θm and √er was strongly linear (0.953 2 dS/m, the relationship θm–√er was not linear, and, thus the TDR300 device calibration became increasingly difficult. Therefore, rather than operating as a time domain device, TDR300 operates as a water content reflectometer type device.

Phenotypic traits and establishment speed of 44 turf bermudagrass accessions

Breeding of turf bermudagrass (Cynodon (L.) Rich.) has made available a broad range of turf varieties with unique morphological and growth traits. Rapid establishment is necessary in order to provide the performance of a mature turf cover in the shortest time possible. The aims of the research were: (1) to determine variation of growth, morphological and biomass traits in bermudagrass accessions belonging to different phenotypic groups during establishment and (2) to relate such variations to establishment speed in order to assess whether contrasting phenotypic traits could induce different establishment patterns in bermudagrass or if a general establishment predictor can be identified for cultivars and ecotypes belonging to the same taxon. Plant material included 44 accessions of bermudagrasses that were grouped in ‘Wild’, ‘Improved’ ‘Hybrid’ and ‘Dwarf types’. Single spaced plants were transplanted in field plots in two locations in Italy (Pisa and Palermo) and allowed to establish without mowing. The following traits were determined: stolon growth rate, internode length, internode diameter and internode volume, phytomer dry weight, leaf width, colour, seed head production, above ground dry biomass, shoot density, horizontal stem density and node density. Establishment speed of accessions was also determined. Stolon growth rate was found to be the only parameter strongly correlated to establishment speed across all entries and for each of the phenotypic groups. Based on these results, stolon growth rate could be assumed as a good predictor of establishment speed for cultivars and ecotypes belonging to the Cynodon genus.

Flame Weeding at Archaeological Sites of the Mediterranean Region

Archaeological sites of the Mediterranean region are widely colonized by weed species causing various problems both to the monuments and the functionality of the sites. Due to recent regulatory restrictions for herbicide use at archaeological sites, flame weeding was studied as an alternative weed management method. The objective of the study was to test two propane doses (99 kg ha-1 and 129 kg ha-1) applied two, three, or four times at three archaeological sites of Greece (Kolona, Ancient Messene and Early Christian Amfipolis). Percent weed control and weed heights were significantly affected by flaming treatments. Visual evaluation of percent weed control suggested that the propane dose of 129 kg ha-1 applied four times provided excellent weed control (>90%) for over 2 months. Annual broadleaf weeds were controlled better with flaming than grasses and perennial broadleaf species. The high propane dose applied four times reduced average vegetation height to about 10 cm, which was the desirable vegetation height wanted by the managers of the archeological sites suggesting that flame weeding has the potential to be used effectively for weed management in archaeological sites of the Mediterranean region.