Simone Magni

Unmanned Aerial Vehicle to Estimate Nitrogen Status of Turfgrasses

Spectral reflectance data originating from Unmanned Aerial Vehicle (UAV) imagery is a valuable tool to monitor plant nutrition, reduce nitrogen (N) application to real needs, thus producing both economic and environmental benefits. The objectives of the trial were i) to compare the spectral reflectance of 3 turfgrasses acquired via UAV and by a ground-based instrument; ii) to test the sensitivity of the 2 data acquisition sources in detecting induced variation in N levels. N application gradients from 0 to 250 kg ha-1 were created on 3 different turfgrass species: Cynodon dactylon x transvaalensis (Cdxt) ‘Patriot’, Zoysia matrella (Zm) ‘Zeon’ and Paspalum vaginatum (Pv) ‘Salam’. Proximity and remote-sensed reflectance measurements were acquired using a GreenSeeker handheld crop sensor and a UAV with onboard a multispectral sensor, to determine Normalized Difference Vegetation Index (NDVI). Proximity-sensed NDVI is highly correlated with data acquired from UAV with r values ranging from 0.83 (Zm) to 0.97 (Cdxt). Relating NDVI-UAV with clippings N, the highest r is for Cdxt (0.95). The most reactive species to N fertilization is Cdxt with a clippings N% ranging from 1.2% to 4.1%. UAV imagery can adequately assess the N status of turfgrasses and its spatial variability within a species, so for large areas, such as golf courses, sod farms or race courses, UAV acquired data can optimize turf management. For relatively small green areas, a hand-held crop sensor can be a less expensive and more practical option.

GeoEye-1 satellite versus ground-based multispectral data for estimating nitrogen status of turfgrasses

Satellite remote sensing of leaf nitrogen (N) content is an interesting technique for agricultural crops for both economic and environmental reasons since it allows the monitoring of fertilization, and hence can potentially reduce the application of N according to real plant needs. The objective of this trial was to compare the N status in different turfgrasses using both remote multispectral data acquired by GeoEye-1 satellite and two ground-based instruments. The study focused on creating a N content gradient on three warm-season turfgrasses, (Cynodon dactylon × transvaalensis ‘Patriot’, Paspalum vaginatum ‘Salam’, Zoysia matrella ‘Zeon’), and two cool-season (Festuca arundinacea ‘Grande’, Lolium perenne ‘Regal 5’). The linear gradient of applied N ranged from 0 to 342 kg ha−1 for the warm-season and from 0 to 190 kg ha−1 for the cool-season turfgrasses. Proximity and remote-sensed reflectance measurements were acquired and used to determine the normalized difference vegetation index (NDVI). Our results proved that proximity-sensed NDVI is highly correlated with data acquired from satellite imagery. The correlation coefficients between data from the satellite and the other sensors ranged from 0.90 to 0.99 for the warm-season and from 0.83 to 0.97 for the cool-season species. ‘Patriot’ had a clippings N content ranging from 1.20% to 4.1%, thus emerging as the most reactive species to N fertilization. As such, the GeoEye-1 satellite can adequately assess the N status of different turfgrass species and its spatial variability within a field, depending on the N rates applied. In future, information obtained from satellites could allow precision fertilizer management on sports fields, golf courses, or other extended green areas.

Carbohydrate content, characterization and localization in bermudagrass stolons during establishment

Abstract Turfgrasses are continuously exposed to a wide range of detrimental stresses, such as mowing, traffic, low or high temperatures, salinity, drought, UV, hypoxia etc. Plant responses to stimuli involve nearly every aspect of plant physiology and metabolism. Carbohydrates, primary sucrose and starch, as principal metabolic products of photosynthesis, are stored in bermudagrass (Cynodon spp.) in stolons and rhizomes. Total nonstructural carbohydrates (TNC) levels have been used as indicators of health and physiological status in bermudagrass. TNC levels vary during the year and are weakly affected by N source. Establishment is a critical phase of bermudagrass management. The objectives of this research were to assess and characterize stolon carbohydrate content in nine bermudagrass cultivars during the full establishment phase in relation to establishment rates. Morphological and growth analyses showed distinct properties among the cultivars selected for this study. Significant differences in turf coverage among cultivars on each rating date were present starting from early growth stages. Carbohydrates localization was used to differentiate bermudagrass cultivars. The relationships between different carbohydrates and their role on growth were also explored. Gradients along the stolon from tip to older internodes were evident for starch. Our study provides further insight into bermudagrass physiology, with cultivar differences in carbohydrates production and localization providing valuable selection information for turfgrass breeders and practitioners, especially during the first year. Our data indicate that TNC levels were affected by cultivar and stolon maturity level. TNC content was found to correlate with establishment rate.

Autonomous Mower Saves Energy and Improves Quality of Tall Fescue Lawn

Battery-powered autonomous mowers are designed to reduce the need of labor for lawn mowing compared with traditional endothermic engine mowers and at the same time to abate local emissions and noise. The aim of this research was to compare autonomousmower with traditional rotary mower on a tall fescue (Festuca arundinacea) lawn under different nitrogen (N) rates. A two-way factor experimental design with three replications was adopted. In the study, four N rates (0, 50, 100, and 150 kg ha) and two mowing systems (autonomous mower vs. gasolinepowered walk-behind rotary mower equipped for mulching) were used. As expected, N fertilization increased turf quality. At the end of the trial, the autonomous mower increased turf density (3.2 shoots/cm) compared with the rotary mower (2.1 shoots/cm) and decreased average leaf width (2.1 mm) compared with the rotary mower (2.7 mm). Increased density and decreased leaf width with autonomous mowing yielded higher quality turf (7.3) compared with the rotary mower (6.4) and a lower weed incidence (6% and 9% cover for autonomous mower and rotary mower, respectively). Disease incidence and mowing quality were unaffected by the mowing system. The autonomous mower working timewas set to 10 hours per day ( 7.8 hours formowing and 2.2 hours for recharging) for a surface of 1296 m. The traditional rotary mower working time for the same surface was 1.02 hours per week. The estimated primary energy consumption for autonomous mower was about 4.80 kWh/week compared with 12.60 kWh/week for gasoline-powered rotary mowing. Based on turf quality aspects and energy consumption, the use of autonomous mowers could be a promising alternative to traditional mowers.

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.

Hydrological characteristics of some volcanic materials as affected by particle size distribution and internal porosity

Abstract A number of internally porous inorganic amendments have been recently introduced to replace peat in rootzone mixes used for golf greens and sports fields. In Italy, volcanic rocks provide a large availability of internally porous materials such as pumice, lapillus and zeolite. Volcanic sands are currently used as substitutes of silica sand. In order to assess the suitability of these volcanic materials for sand amelioration and/or as construction materials, the present research was aimed at studying the water retention and release of these materials considering different particle size distributions and a non-porous silica sand as a reference. Water retention curves were constructed for the internally porous sands as: (a) raw material, (b) graded material with the same particle size distribution of a non-internally porous silica sand. Additionally, available water was determined on specific sand fractions namely coarse sand (0.5–1.0 mm) and medium sand (0.25–0.5 mm) of all the materials. The available water content of raw volcanic materials was higher than of graded sands made of the same materials, thus showing the expected effect of texture on water retention. The comparison of water retention properties of the internally porous materials and non-internally porous silica sand with the same particle size distribution, showed a significant contribution given by internal porosity to water retention. Volcanic coarse sand fraction showed higher water availability than volcanic medium sand fraction. Volcanic materials used as amendments could enhance the water availability of sand-based rootzones, but if used as raw materials the possibility exists for the final mix not to meet the specifications for sports use. The use of sole volcanic sands as rootzone material could have a major impact on water-holding capacity, and hence on management, although investigation on their particle stability is still needed.

Steaming and flaming for converting cool-season turfgrasses to hybrid bermudagrass in untilled soil

Turfgrass species can be classified into two main groups: cool-season and warm-season species. Warm-season species are more suited to a Mediterranean climate. Transplanting is a possible method to convert a cool-season to a warmseason turfgrass in untilled soil. It generally requires the chemical desiccation of the cool-season turfgrass. However, alternative physical methods, like flaming and steaming, are also available. This paper compares flaming, steaming, and herbicide application to desiccate cool-season turfgrass, for conversion to hybrid bermudagrass (Cynodon dactylon x C. transvaalensis) in untilled soil, using transplanting. Two prototype machines were used, a self-propelled steaming machine and a tractor-mounted liquefied petroleum gas flaming machine. Treatments compared in this workwere two flaming treatments and two steaming treatments performed at four different doses together with two chemical treatments with glufosinateammoniumherbicide applications. The cool-season turfgrass species were tall fescue (Festuca arundinacea) and perennial ryegrass (Lolium perenne). The desiccation effect of the various treatments on cool-season turf was assessed by photographic survey 15 days after treatment. The percentage cover of hybrid bermudagrass was visually assessed at 43 weeks after planting. Steaming and flaming effects on both parameters were described by logistic curves. The highest doses of steaming and flaming almost completely desiccated cool-season turf, and similar hybrid bermudagrass cover was established by both the methods as the chemical application (50% to 60%). Thus both flaming and steaming may be considered as valid alternatives to herbicides aimed at turf conversion.