Stefano Benvenuti

Quantitative analysis of emergence of seedlings from buried weed seeds with increasing soil depth

Abstract Trials were carried out to investigate the effects of seed burial depth on seedling emergence rate of 20 weed species. Marked depth-mediated variation in emergence ability of the different species was observed, together with a general pattern of decreasing emergence with increasing soil depth. At 10 cm, only johnsongrass, velvetleaf, catchweed bedstraw, and cutleaf geranium emerged, albeit only in limited numbers. Species most severely inhibited by burial depth were buckhorn plantain, large crabgrass, common purslane, chickweed, and corn spurry, none of which emerged from beyond 6 cm. In all species, depth-mediated inhibition was found to be sigmoidal (polynomial regression). In addition, the number of seedlings and rate of seedling emergence decreased when depth of burial increased. The depth at which the number of emerged seedlings was halved varied by species and ranged from 3.6 cm for common purslane and chickweed to 7 cm for velvetleaf and catchweed bedstraw. Excessive burial depth generally induced dormancy (in roughly 85% of cases) rather than suicide germination. A close inverse relation (second-degree equation) between seed unit weight and depth-mediated inhibition was observed. The physiological involvement of depth inhibition in seed bank ecology is discussed. Nomenclature: Buckhorn plantain, Plantago lanceolata L. PLALA; catchweed bedstraw, Galium aparine L. GALAP; common chickweed, Stellaria media (L.) Vill. STEME; common purslane, Portulaca oleracea L. POROL; corn spurry, Spergula arvens L. SPRAR; cutleaf geranium, Geranium dissectum L. GERDI; johnsongrass, Sorgum halepense (L.) Pers. SORHA; large crabgrass, Digitaria sanguinalis (L.) Scop. DIGSA; velvetleaf, Abutilon theophrasti Medicus ABUTH.

Weed-insect pollinator networks as bio-indicators of ecological sustainability in agriculture. A review

The intensification of agricultural practices contributes to the decline of many taxa such as insects and wild plants. Weeds are serious competitors for crop production and are thus controlled. Nonetheless, weeds enhance floral diversity in agricultural landscapes. Weeds provide food for insects in exchange for pollination. The stability of mutualistic interactions in pollination networks depends on conservation of insect pollinator and weed communities. Some agricultural practices can destabilize interactions and thus modify the stability of pollination networks. Therefore, more knowledge on weed-insect networks is needed. Here, we review the interactions involved in insect visits to weed flowers in temperate arable lands. Our main findings are that (1) weed pollination by insects has a key role in maintaining weed communities in arable lands; (2) weed-insect pollinator interactions are modulated by the flowers’ features and their quality which are attracting insects; (3) most weeds are associated with generalist insect pollinators; and (4) even if weed-pollinator networks are largely mutualistic, some antagonist networks can be observed when deception occurs. We propose three weed-insect pollinator networks as potential bio-indicators to evaluate the ecological sustainability of arable land management strategies in temperate areas: (1) Geometridae and Bombyliidae species visiting Caryophyllaceae, (2) Papilionidae foraging on Apiaceae, and (3) Syrphidae visiting Asteraceae.

Temperature and Water Potential as Parameters for Modeling Weed Emergence in Central-Northern Italy

Abstract Predicting weed emergence dynamics can help farmers to plan more effective weed control. The hydrothermal time concept has been used to model emergence as a function of temperature and water potential. Application of this concept is possible if the specific biological thresholds are known. This article provides a data set of base temperature and water potential of eight maize weeds (velvetleaf, redroot pigweed, common lambsquarters, large crabgrass, barnyardgrass, yellow foxtail, green foxtail, and johnsongrass). For five of these species, two ecotypes from two extreme regions of the predominant maize-growing area in Italy (Veneto and Tuscany), were collected and compared to check possible differences that may arise from using the same thresholds for different populations. Seedling emergence of velvetleaf and johnsongrass were modeled using three different approaches: (1) thermal time calculated assuming 5 C as base temperature for both species; (2) thermal time using the specific estimated base temperatures; and (3) hydrothermal time using the specific, estimated base temperatures and water potentials. All the species had base temperatures greater than 10 C, with the exception of velvetleaf (3.9 to 4.4 C) and common lambsquarters (2.0 to 2.6 C). All species showed a calculated base-water potential equal or up to −1.00 MPa. The thresholds of the two ecotypes were similar for all the studied species, with the exception of redroot pigweed, for which the Veneto ecotype showed a water potential lower than −0.41 MPa, whereas it was −0.62 MPa for the Tuscany ecotype. Similar thresholds have been found to be useful in hydrothermal time models covering two climatic regions where maize is grown in Italy. Furthermore, a comparison between the use of specific, estimated, and common thresholds for modeling weed emergence showed that, for a better determination of weed control timing, it is often necessary to estimate the specific thresholds. Nomenclature: Barnyardgrass, Echinochloa crus-galli (L.) Beauv. ECHCG; common lambsquarters, Chenopodium album L. CHEAL; green foxtail, Setaria viridis (L.) Beauv. SETVI; johnsongrass, Sorghum halepense (L.) Pers. SORHA; large crabgrass, Digitaria sanguinalis (L.) Scop. DIGSA; redroot pigweed, Amaranthus retroflexus L. AMARE; velvetleaf, Abutilon theophrasti Medik. ABUTH; yellow foxtail, Setaria pumila (Poir.) Roemer & J. A. Schultes SETLU.

Cephalaria transsylvanica-based flower strips as potential food source for bees during dry periods in European Mediterranean basin countries.

The introduction of sown wildflower strips favours the establishment of pollinator communities, with special reference to social Apoidea. Here, we evaluated the late summer flowering Cephalaria transsylvanica as suitable species for strips providing food for pollinators in paucity periods. C. transsylvanica showed no particular requirements in terms of seed germination and growth during summer. This plant had an excellent potential of self-seeding and competitiveness towards weed competitors. C. transsylvanica prevented from entomophilous pollination showed inbreeding depression, with a decrease in seed-set and accumulation of seed energy reserves. However, C. transsylvanica did not appear to be vulnerable in terms of pollination biology since it had a wide range of pollinators including bees, hoverflies and Lepidoptera. C. transsylvanica was visited mainly by honeybees and bumblebees and these latter pollinators increased their visits on C. transsylvanica flowers during early autumn. This plant may be useful as an abundant source of pollen during food paucity periods, such as autumn. We proposed C. transsylvanica for incorporation into flower strips to be planted in non-cropped farmlands in intensively managed agricultural areas as well as in proximity of beehives. The latter option may facilitate the honeybees collecting pollen and nectar for the colony, thereby ensuring robustness to overcome the winter season.

Metal contamination in urban street sediment in Pisa (Italy) can affect the production of antioxidant metabolites in Taraxacum officinale Weber.

Taraxacum officinale Weber (dandelion) is a very ubiquitous species, and it can grow in urban environments on metal-polluted sediments deposited in the gutters. This study represents a preliminary step to verify the presence of metals in sediments collected in urban streets in Pisa and to assess the alteration in dandelion metabolites in order to understand its adaptation to polluted environments. The soil and sediments were collected at three urban streets and analyzed for total and extractable Cr, Pb, Cu, Ni, and Zn. The total values of Pb and Zn in street sediments exceeded the limits for residential areas of soils. Zn was the most mobile of the metals analyzed. Floating cultivations trials were set up with dandelion seedlings and street sediments. The metals were analyzed in roots and leaves. Antioxidant power, anthocyanins, polyphenols, non-protein thiols (NP-TH) and chlorophylls were measured in dandelion leaves. The first two parameters (anthocyanins and antioxidant power) were higher in the polluted samples compared to the control; chlorophyll content was lower in the treated samples, whereas NP-TH showed no differences. NP-TH groups determined in roots were associated with the root content of Zn and Pb. These results indicate that dandelion can tolerate plant stress by altering its metabolite content.

Modeling Weed Emergence in Italian Maize Fields

Abstract A hydrothermal time model was developed to simulate field emergence for three weed species in maize (common lambsquarters, johnsongrass, and velvetleaf). Models predicting weed emergence facilitate well-timed and efficient POST weed control strategies (e.g., chemical and mechanical control methods). The model, called AlertInf, was created by monitoring seedling emergence from 2002 to 2008 in field experiments at three sites located in the Veneto region in northeastern Italy. Hydrothermal time was calculated using threshold parameters of temperature and water potential for germination estimated in previous laboratory studies with seeds of populations collected in Veneto. AlertInf was validated with datasets from independent field experiments conducted in Veneto and in Tuscany (west central Italy). Model validation resulted in both sites in efficiency index values ranging from 0.96 to 0.99. AlertInf, based on parameters estimated in a single region, was able to predict the timing of emergence in several sites located at the two extremes of the Italian maize growing area. Nomenclature: common lambsquarters, Chenopodium album L.,CHEAL; johnsongrass, Sorghum halepense L. Pers, SORHA; velvetleaf, Abutilon theophrasti Medik., ABUTH.

First record of insect pollinators visiting Muscari comosum (L.) Miller (Liliaceae-Hyacinthaceae), an ancient Mediterranean food plant

Insects foraging on Muscari comosum flowers belong to 3 families, 10 genera and 13 species. The most abundant species was the hairy-footed flower bee, Anthophora plumipes. All species, except two cleptoparasites, presented pollen on their bodies. Muscari comosum flowering in early spring can be a key food source for pollinators.

Insect pollinators of the late winter flowering Rhamnus alaternus L., a candidate for honeybee-friendly scrubland spots in intensively managed agricultural areas

Insect pollinators of Rhamnus alaternus belong to 11 families, 17 genera and 20 species. The most abundant species is the honeybee followed by flies and bumblebees. Honeybee visits on R. alaternus decreased from late winter to early spring, highlighting the key role of this flowering in food paucity periods.

Biodiversity of Flora and Fauna

Rooftop farming can contribute to urban biodiversity in terms of providing habitats and creating an urban green network. In addition, the cultivation of plants on roofs can provide places where wild animals and plants can survive and reproduce. Chosen cultivation practices and plant species can improve habitats and present more opportunities for wildlife and if flowering plants are grown together with vegetables, wild pollinators and domestic bees are attracted, providing pollination for edible species too.

Mediterranean Wild Edible Plants: Weeds or “New Functional Crops”?

The Mediterranean basin is a biodiversity hotspot of wild edible species, and their therapeutic and culinary uses have long been documented. Owing to the growing demand for wild edible species, there are increasing concerns about the safety, standardization, quality, and availability of products derived from these species collected in the wild. An efficient cultivation method for the species having promising nutraceutical values is highly desirable. In this backdrop, a hydroponic system could be considered as a reproducible and efficient agronomic practice to maximize yield, and also to selectively stimulate the biosynthesis of targeted metabolites. The aim of this report is to review the phytochemical and toxic compounds of some potentially interesting Mediterranean wild edible species. Herein, after a deep analysis of the literature, information on the main bioactive compounds, and some possibly toxic molecules, from fifteen wild edible species have been compiled. The traditional recipes prepared with these species are also listed. In addition, preliminary data about the performance of some selected species are also reported. In particular, germination tests performed on six selected species revealed that there are differences among the species, but not with crop species. “Domestication” of wild species seems a promising approach for exploiting these “new functional foods”.