Cover crops for managing weeds, soil chemical fertility and nutritional status of organically grown orange orchard in Sicily

Cover crops can offer significant advantages in the agronomic management of citrus orchards in Mediterranean environments. Therefore, a three-year research was conducted in eastern Sicily aimed at studying the effects of four cover crop sequences (Sinapis arvensis-Trigonella foenum-graecum-T. foenum-graecum; Medicago scutellata-Avena sativa-Lolium perenne; Vicia faba minor-A. sativa-A. sativa; A. sativa-V. faba. minor-L. perenne) on weeds, major soil chemical properties and nutritional status of an organically grown orange orchard. The results highlighted that, among the studied cover crop sequences, Vicia faba-Avena-Avena was the most beneficial for weeds control within the orchard (92%, of cover crop cover, and 586 and 89 g DW m–2 of cover crop aboveground biomass and weeds aboveground biomass, respectively). Overall, the chemical fertility of the soil was positively influenced. In particular, it was observed an increase of the content of total nitrogen and available phosphorus in the soil by both Sinapis-Trigonella-Trigonella (0.75 g kg–1 and 59.0 mg kg–1, respectively) and Vicia faba-Avena-Avena (0.70 g kg–1 and 56.0 mg kg–1, respectively) cover crop sequences. Medicago-Avena-Lolium sequence seemed to be the most useful to ensure a better nutritional status of the orange orchard

Allelopathic potential of leaf aqueous extracts from Cynara cardunculus L. on the seedling growth of two cosmopolitan weed species

The search for sustainable alternatives to synthetic herbicides for weed control, has led the scientific community to an increased interest for plant allelopathic mechanisms. The utilization of plant extracts as possible bioherbicides represents an important solution. In the present study, laboratory experiments were carried out to investigate, for the first time, the differences in the allelopathic activity of the three Cynara cardunculus L. botanical varieties (globe artichoke, cultivated and wild cardoon) leaf aqueous extracts on the seedling growth of Amaranthus retroflexus L. and Portulaca oleracea L. In addition, the autoallelopathic effect on wild cardoon growth and the qualitative profile of the aqueous extract through HPLC analysis were evaluated. Overall, the allelopathic effects were both genotype- and weed species-dependent. Wild cardoon showed the highest allelopathic potential (–23.4%), followed by cultivated cardoon and globe artichoke, and P. oleracea was the most sensitive target species (–32%). Besides, root system length was the most affected parameter (–32.6%). The autoallelopathic effect of wild cardoon extract was also demonstrated on root system length, hypocotyl and epicotyl length and total dry weight. C. cardunculus leaf aqueous extract was characterised by 5 sesquiterpene lactones, 2 caffeoylquinic acids, 6 flavones and 1 lignan. From the HPLC analysis we found that apigenin and luteolin 7-O-glucoronide were detected only in wild cardoon, apigenin 7-O-glucoside was typic of globe artichoke, and 11,13-dihydro-desacylcynaropicrin and 11,13-dihydroxi-8-desoxygrosheimin were characteristics of cultivated cardoon

Biological Characteristics and Control of Orobanche Crenata Forsk., a Review

Orobanche crenata is a holoparasitic phanerogam which is particularly noxious to legumes, such as faba bean (Vicia faba L.), pea (Pisum sativum L.), chickpea (Cicer arietinum L.), lentil (Lens culinaris Medik.), etc., and commonly considered one of the major causes which has contributed to re-rizing the area designed to their cultivation. After a few brief references on the origin and diffusion of O. crenata, in this work summarises the results of research into biological aspects and control of this species. The information obtained especially concerns seed production, seed viability, seed longevity and dormancy, seed conditioning and germination, parasitism phases, the effects of parasite attacks on host plants and the means of control

Impact of a Cultivation System upon the Weed Seedbank Size and Composition in a Mediterranean Environment

The knowledge of the soil seedbank is crucial to predict the dynamics of weed communities and potential future problems in agroecosystem weed management. Therefore, the aim of this study was to evaluate the qualitative and quantitative variation of the potential and real weed flora as a function of different cultivation systems (namely organic, conventional and uncultivated) in a Mediterranean environment (Sicily, south Italy). The results proved that soil seedbank density was significantly different in superficial (0–10 cm) and deeper soil layers (10–15 cm) in both organic and conventional cultivation systems. Portulacaceae and Amaranthaceae were the dominant botanical families, although they achieved a higher total number of seeds m−2 under a conventional cultivation system than under organic and uncultivated ones. The whole weed flora was represented by 45 taxa, but the presence of the crop reduced the qualitative and quantitative composition of real weed flora. In conclusion, the knowledge of the seedbank size and composition, as well as the variation in time and space of real flora, may contribute to predict the dynamics of weed emergence and their possible interference with crops. In particular, information on the weed dynamics is essential to develop sustainable control protocols, especially under organic farming

Differentiated Weed-Suppressive Ability of Modern and Old Durum Wheat Cultivars after Long-Term Cultivation under Semi-Arid Climate

Durum wheat (Triticum turgidum spp. durum) is one of the most important grain crops cultivated across the Mediterranean Basin, where a strong return to local landraces cultivation is occurring to meet the market demand for high-quality food and low-input cropping systems. A characterisation of the long-term effect (10 years) of durum wheat landraces and modern cultivars on the potential and real weed flora is still lacking. Hence, a multilocation trial over 10 farms in Central-Eastern Sicily was carried out to investigate the repeated cultivation of several old landraces (OLD) and modern cultivars (MOD) on the abundance and diversity of weed flora. Overall, OLD was associated with a 47% reduction of the soil seedbank size and to −64% of the aboveground weed biomass compared to MOD. In addition, diversity indices pointed out a high similarity between MOD and OLD farm groups for the soil seedbank, while a lower diversity was found in OLD for aboveground weed communities. From the principal component analysis emerged that the species compositions of MOD and OLD were quite separated for both soil seedbank and real flora, with the latter showing few specific associations with major weeds. These findings demonstrated the indirect effect of durum wheat landraces in sustainably reducing weed pressure without the adoption of chemical weed control

Allelopathic effects of Cynara cardunculus L. leaf aqueous extracts on seed germination of some Mediterranean weed species

It is known that the presence of weeds causes serious losses to the agricultural production, both in quantitative and qualitative terms. The major problem in modern agriculture is the environmental impact of synthetic herbicides and the increase in herbicide- resistant weed species. Allelopathic compounds can be used to develop a sustainable weed management system based on natural products. The objective of this study was to evaluate the allelopathic potential of leaf aqueous extracts (40 and 80%) obtained from Cynara cardunculus L. plant species on seed germination and mean germination time of six common weeds in Mediterranean agroecosystems: Amaranthus retroflexus L., Diplotaxis erucoides (L.) DC., Portulaca oleracea L., Lavatera arborea L., Brassica campestris L. and Solanum nigrum L. Effects varied with the weed species and the concentrations of the extracts. On average, the aqueous leaf extracts significantly reduced the final percentage of seed germination compared to the control for A. retroflexus (–58.1%), D. erucoides (–43.9%) and P. oleracea (–42.5%). The rate of germination decreased with increasing extract concentration. In C. cardunculus L. var. sylvestris the autoallelopathic activity also was demonstrated. These results are very promising in order to produce a bioherbicide based on C. cardunculus allelochemicals

Allelopathy in Durum Wheat Landraces as Affected by Genotype and Plant Part

Durum wheat is one of the largest cultivated crops across Mediterranean areas. The high demand for sustainable crop productions, especially concerning weed management, is driving the return to local landraces. In the present work, the in vitro allelopathic effects of the extracts of three durum wheat landraces (‘Timilia’, ‘Russello’ and ‘Perciasacchi’) and a modern variety (‘Mongibello’), obtained from three different plant parts (ears, stems and roots), were tested on seed germination (G) and mean germination time (MGT) of Portulaca oleracea L. and Stellaria. media (L.) Vill., two weeds commonly infesting wheat fields. In addition, the total polyphenol (TPC) and total flavonoid (TFC) content of extracts was determined. All extracts reduced G and increased MGT in both weeds compared to the control. The magnitude of phytotoxicity was strongly affected by the influence of genotype, plant part and extract dilution. Overall, the landraces ‘Timilia’ and ‘Russello’ showed the highest allelopathic effects, ear extracts were the most active, and the maximum extract dilution induced higher phytotoxicity. Extracts’ TPC and TFC corroborated these results. The findings obtained here encourage the use of local landraces as a source of allelochemicals and suggest that they could be left on soil surface or soil-incorporated after harvest for a possible weed control

Allelopathy in Durum Wheat Landraces as Affected by Genotype and Plant Part

Durum wheat is one of the largest cultivated crops across Mediterranean areas. The high demand for sustainable crop productions, especially concerning weed management, is driving the return to local landraces. In the present work, the in vitro allelopathic effects of the extracts of three durum wheat landraces (‘Timilia’, ‘Russello’ and ‘Perciasacchi’) and a modern variety (‘Mongibello’), obtained from three different plant parts (ears, stems and roots), were tested on seed germination (G) and mean germination time (MGT) of Portulaca oleracea L. and Stellaria. media (L.) Vill., two weeds commonly infesting wheat fields. In addition, the total polyphenol (TPC) and total flavonoid (TFC) content of extracts was determined. All extracts reduced G and increased MGT in both weeds compared to the control. The magnitude of phytotoxicity was strongly affected by the influence of genotype, plant part and extract dilution. Overall, the landraces ‘Timilia’ and ‘Russello’ showed the highest allelopathic effects, ear extracts were the most active, and the maximum extract dilution induced higher phytotoxicity. Extracts’ TPC and TFC corroborated these results. The findings obtained here encourage the use of local landraces as a source of allelochemicals and suggest that they could be left on soil surface or soil-incorporated after harvest for a possible weed control