Filippo Lulli

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.

Turfgrass spectral reflectance: simulating satellite monitoring of spectral signatures of main C3 and C4 species

In recent years, within the European Union several legislative, monitoring and coordinating actions have been undertaken to encourage sustainable use of resources, reduction in the use of chemicals and improvement of the urban environment. In this respect, two concepts that are strictly related to most of the aspects above are: “precision agriculture” and “precision conservation” and more specifically “precision turfgrass management.” Optical sensing has become a crucial part of precision turfgrass management and spectral reflectance in particular has been an active area of research for many years. However, while turfgrass status evaluation by proximity-sensed spectral reflectance appears to be an established and reliable practice, much more could be achieved in terms of monitoring of large turfgrass areas through remote sensing, and in particular through satellite imagery. This paper reports the results of a trial attempting to evaluate the spectral signatures of several turfgrass species and cultivars, for future use in turfgrass satellite monitoring. Our experimental study focused on 20 turfgrass species/varieties including perennial ryegrasses, tall fescues, kentucky bluegrasses, bermudagrass ecotypes, seeded commercial bermudagrasses, vegetatively propagated bermudagrasses, Zoysia japonica and non-japonica zoysiagrasses. Various biological and agronomical parameters were studied and turfgrass spectral reflectance for all entries was gathered. Vegetation indices were calculated by simulating the available wavelengths deriving from World View 2 satellite imagery. Results showed that within the same species selected vegetation indices are often able to discriminate between different varieties that have been established and maintained with identical agronomical practices.

An innovative hybrid natural–artificial sports pitch construction system

Third-generation artificial-turf pitches are often criticized because of their high abrasiveness when athletes fall on the surface, the high temperatures recorded in summer periods, and their unpleasant rubber odour. On the other hand, natural-turf pitches are not able to withstand the high play volumes currently associated with modern high-profile and community sports pitches. Hybrid systems with a varying presence of artificial fibres and reinforcements have long been tested and installed, without providing a definitive answer to the above-mentioned problems of natural turf. The aim of this study was to evaluate the playing characteristics and the wear resistance of a newly patented hybrid natural-artificial sports pitch construction system after rugby and football play for 2 months and 5 months. This hybrid system consists of a modified third-generation artificial grass with organic infill, on which natural grass was allowed to grow. A 11300 m2 experimental pitch was constructed in Pisa (Italy) in the summer of 2007 and tested during 2007–2008 following football and rugby union play for an average of 8–9 h/week. The hybrid pitch showed a total absence of rubber odour, summer temperatures similar to those of natural-turf pitches, wear resistance superior to that of natural-turf pitches, abrasiveness similar to that of natural-turf pitches, and good infill particle size stability. Most playing-quality parameters fell within both the Fédération Internationale de Football Association (FIFA) Recommended 2-Star Standard requirements for artificial turf and generally accepted playing-quality parameters for natural turf. Since then more pitches as described herein have been constructed and witnessed international match play, while FIFA has classified the system as a reinforced natural-grass pitch.