Nicola Grossi

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.

Physiological and morphological factors influencing leaf, rhizome and stolon tensile strength in C4 turfgrass species

The intrinsic resistance of plant tissue to several biomechanical stresses, including tensile stress, is a decisive factor in determining the wear resistance of a turfgrass species. Lignin, dry matter, starch, sugars and silica are some of the tissue constituents that have been associated with leaf and stem mechanical resistance, whereas little information is available concerning stolons and rhizomes. These organs not only enable C4 turfgrass species lateral growth, soil colonisation and injury recovery, but are also key constituents of mature swards. This study consisted in an extensive investigation on the effective leaf, stolon and rhizome tensile strength of Cynodon dactylon (L.) Pers. var. dactylon×C. transvaalensis Burt-Davy cv. Tifway 419, Zoysia matrella (L.) Merr. cv. Zeon and Paspalum vaginatum Swartz. cv. Salam, as measured with a Fédération Internationale de Football Association (FIFA)-approved dynamometer and correlating the results with laboratory investigations on key tissue constituents. Tensile strength per unit area was influenced by both tissue constituents and tissue dimension. In rhizomes and stolons, tissue breakage usually occurred in the area at the intercalary meristem at the apical zone in the immediate proximity of a node. Older tissues had higher tensile strength owing to their higher levels of lignification. Lignin was the principal constituent determining tissue tensile strength and as such it could be used as a turfgrass wear resistance predictor in the cultivar breeding stages. Stolon total soluble sugars were generally inversely proportional to lignin content and, therefore, can also be considered clear markers of tissue mechanical strength. Silica was found to have no influence on the mechanical properties tissues.

Physiological and morphological factors influencing wear resistance and recovery in C3 and C4 turfgrass species

High turfgrass wear resistance and recovery are the most sought after characteristics in turfgrass species when used for sports turf, but they are also very important in home gardens and public parks. Several wear resistance investigations have been conducted in field conditions in recent years, but these investigations involved the use of machinery and techniques that are not able to segregate the plant wounding and death effects from soil compaction effects that are generally associated with turfgrass wear. The same can be said of wear recovery investigations, with an extensive use of agronomical machinery for field trials. This study focussed on the wear resistance and recovery of mature swards of Cynodon dactylon (L.) Pers. var. dactylon×C. transvaalensis Burt-Davy cv. Tifway 419, Zoysia matrella (L.) Merr. cv. Zeon and Paspalum vaginatum Swartz. cv. Salam and a typical sports-type mix of Lolium perenne L. (cvv. Speedster 35% and Greenway 35%)+Poa pratensis L. (cvv. SR2100 15% and Greenknight 15%). The goal of this trial was to evaluate turfgrass wear resistance and recovery devoid of climatic and soil effects and thus, sward growing, wear simulation and recovery were conducted in controlled environment. Furthermore, wear simulation was conducted with FIFA-approved, numerical control machinery (Lisport). Wear resistance and recovery data was plotted against results from laboratory investigations on key tissue constituents. Zoysia matrella proved to be the most wear resistant, but the slowest in recovery, whereas the bermudagrass hybrid showed the exact opposite behaviour. Lignin and carbohydrate concentrations proved to be the two factors most closely correlated with wear resistance and recovery respectively. These two classes of compounds were present in an equilibrium that was species specific, with a frequent mutual exclusion between lignin and starch concentrations that deserves further investigation at the intra-specific level.

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.

Effects of Application of Municipal Solid Waste Compost on Horticultural Species Yield

Composting as a means of waste recycling in order to produce organic fertilizer has long been practised by farmers. Agronomic interest in compost is due to its elevated nutrient and organic matter content. However compost could have an adverse impact on account of its salinity or the presence of pathogens or toxic metals. Numerous studies on this last aspect have shown that heavy metal content in compost treated plant does not differ significantly from the control (Massantini et al., 1988; Stilwell, 1993). The agronomic trials carried out on compost have shown conflicting results for marked variability in composition, type of species grown and pedoclimatic characteristics of the trial area (Del Zan, 1989; Edwards et al., 1993; Paris et al., 1986). The purpose of the present research was to study the direct and residual agronomic effects of compost from treated municipal solid waste on horticultural species.

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.

Carbohydrate Metabolism During Wintering Period in Four Zoysiagrass Genotypes

Abstract A key barrier to widespread use of warm-season grasses in the transition zone between the temperate and subtropical climates is represented by the winter dormancy, a temporary suspension of visible growth of any plant structure including the meristem. In this environment, species with different photosynthetic carbon cycle coexist, leading to asynchrony in growth among warm- and cool-season grasses. The objectives of the present study were (i) to assess the carbohydrate content in four representative zoysiagrasses Zoysia japonica ‘El Toro’, ‘Meyer’, Z. pacifica, and Z. matrella ‘Zeon’ during three successive phases of vegetation phenology, senescence, dormancy, and green-up, and (ii) to characterize the metabolic responses to phenological variations under natural acclimation. Japanese lawn grass genotypes ‘El Toro’ and ‘Meyer’ showed longer dormancy periods than fine-leaved Z. pacifica and ‘Zeon’. In Japanese lawn grass genotypes, the progressive decline of photosynthetic pigments was similar to that observed in the color retention. Over the experimental period, a significantly greater amount of starch reserves was observed in sprigs (horizontal stems) in the Japanese lawn grasses than in the fine-leaved zoysiagrasses. In general, total soluble sugars (TSS) in leaves and sprigs did not show evidence of sugar starvation during the senescence phase. TSS increased significantly during cold acclimation, resulting in a higher metabolic activity at the onset of green-up to support spring regreening in all zoysiagrasses except ‘Meyer’ leaves.

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.