Horseweed, [Conyza canadensis (L.) Cronq.], has been the most frequent weed species to develop resistance to glyphosate in various parts of the world, including Greece. In order to investigate the resistance mechanism, susceptible (S) and resistant ®) populations collected from regions across Greece were studied. Real-time PCR was used to determine the expression levels of the key enzyme EPSPS and the four ABC transporter genes M10, M11, M7 and P3. The expression level of those genes was studied at early (1DAT) or late (4DAT) times after glyphosate treatment, applied at normal (720 g a.i. ha −1 ) and high (5.760 g a.i. ha −1 ) glyphosate rate. The proposed resistance mechanism was found not to be due to a point mutation at codon 106 of the EPSPS gene that regulates glyphosate metabolism (target-site resistance), but rather involved synchronization of the overexpression of EPSPS and ABC-transporter genes. This synchronization mechanism was based on (1) the time of induction and duration of gene overexpression, and (2) regulation by the initial glyphosate load.

Overreliance on glyphosate can increase the risks of reduced efficacy of the herbicide on weeds and weed resistance, even in regions without glyphosate-resistant crops. That is the reality in Greece, with frequent reports of reduced efficacy of glyphosate against increasingly problematic weeds, such as Conyza spp. The objectives of this study were to determine the occurrence of glyphosate resistance in hairy fleabane populations in central and southern Greece and the effect of weed growth stage on glyphosate efficacy under controlled environmental conditions and to evaluate alternative herbicides in field trials for control of glyphosate-resistant and -susceptible hairy fleabane. Plants from 60 accessions of hairy fleabane, sampled from five prefectures in Greece, were sprayed with glyphosate at 0.36 kg ae ha−1; 15 were classified as potentially resistant. After initial screening, 15 potentially susceptible or resistant accessions were selected and dose–response experiments were conducted. Glyphosate rates required to control some accessions were four to seven times greater than that for control of the reference susceptible accession, AR4. Sensitivity of a resistant hairy fleabane accession to glyphosate was strongly dependent on growth stage, with plants at the seedling stage being most sensitive to the herbicide. A field trial indicated that diquat, glufosinate, or glufosinate + oxyfluorfen controlled glyphosate-resistant or -susceptible hairy fleabane. These herbicides, along with various integrated management strategies, have good potential to manage or slow the spread of glyphosate resistance in this species.

The demand for organically grown products is increasing because many people are concerned about the environment and believe that organic products are healthier than conventional ones. Some studies have shown that organically produced tomato fruits contain higher levels of antioxidants, polyphenols and carotenoids than those produced conventionally. The objective of this study was to evaluate the influence of organic and inorganic fertilization on agronomic and quality characteristics of the processing tomato. The 2-year experiment was laid out in a randomized complete block design, with three replications and three fertilization treatments (untreated, compost and inorganic fertilizer). The results showed that the highest fruit number per plant (98.5), average fruit weight (63.6 g) and fruit yield (168.0 t ha−1) were obtained under inorganic fertilization. The highest total soluble solids (4.39 °Brix) and total soluble solids to titratable acidity ratio (17.4), L* (43.4) and a* (35.4) values, as well as the highest lycopene content (88.5 mg kg−1 f.w). were achieved through the application of organic fertilizer. Significantly higher total soluble solids and total soluble solids to titratable acidity ratio in organically grown tomatoes are particularly important to the processing tomato industry. Finally, the highest lycopene content produced under organic fertilization as well as the non-significant difference between the organic and conventional tomatoes in terms of lycopene yield make organic processing tomatoes suitable for lycopene production.

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SummaryFarmers have access to many data-intensive technologies to help them monitor and control weeds and pests. Data collection, data modelling and analysis, and data sharing have become core challenges in weed control and crop protection. We review the challenges and opportunities of Big Data in agriculture: the nature of data collected, Big Data analytics and tools to present the analyses that allow improved crop management decisions for weed control and crop protection. Big Data storage and querying incurs significant challenges, due to the need to distribute data across several machines, as well as due to constantly growing and evolving data from different sources. Semantic technologies are helpful when data from several sources are combined, which involves the challenge of detecting interactions of potential agronomic importance and establishing relationships between data items in terms of meanings and units. Data ownership is analysed using the ethical matrix method to identify the concerns of farmers, agribusiness owners, consumers and the environment. Big Data analytics models are outlined, together with numerical algorithms for training them. Advances and tools to present processed Big Data in the form of actionable information to farmers are reviewed, and a success story from the Netherlands is highlighted. Finally, it is argued that the potential utility of Big Data for weed control is large, especially for invasive, parasitic and herbicide-resistant weeds. This potential can only be realised when agricultural scientists collaborate with data scientists and when organisational, ethical and legal arrangements of data sharing are established.

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Fibre hemp is grown for a multitude of end products derived from its cannabinoids, seed, fibre and wooden core. A key factor that influences the quantity and quality of the production of hemp is nitrogen fertilization. The aim of this study was to determine the response of five well-adapted industrial hemp cultivars to different nitrogen fertilization rates during the 2016 growing season. The experiment was laid out in a split-plot design with two replicates, five main plots (hemp cultivars: 'Bialobrzeskie', 'Tygra', 'Felina 32', 'Sanhtica 27', 'Futura 75') and sub-plots [fertilization treatments: control (N0), fertilizer 46-0-0 at 120 kg ha -1 (N1), 180 kg ha -1 (N2), 240 kg ha -1 (N3)]. For the computation of height, biomass yield, stem dry weight, length and weight of the inflorescences and mean seed weight, 10 plants were randomly selected in each plot. In general, increasing N fertilization rate positively impacts hemp biomass yield, stem dry weight, plant height, and inflorescence indices. Biomass yield, stem dry weight and inflorescence weight increased by 37.3%, 48.2% and 16%, respectively, with the application of 240 kg N ha -1 when compared with the unfertilized control. Plant height and inflorescence length increased from 1.66 to 1.76 m and from 66.2 to 82.9 cm, respectively, with the application of the higher N rate compared with the control, while there were no significant differences between the fertilization treatments for mean seed weight. The varieties 'Tygra' and 'Futura 75' showed the highest values for all the measurement characters. Our results indicate that hemp responded well to the addition of N fertilizer.

Weeds pose a major threat to world agriculture by reducing detrimentally crop yield and quality. However, at the same time, weeds are major interacting components of the agroecosystems. Abundance and diversity of weeds vary significantly among the several communities. In order to evaluate each community's structure and the interactions among them, several population indices are used as key tools. In parallel, various cultivation and land management strategies, such as tillage and fertilization, are commonly used in terms of integrated weed management. Estimating the response of weed species on those practices is crucial for both biodiversity maintenance and alternative weed control methods. Many experiments have confirmed the fundamental role of tillage intensity and nutrition supply in weed species' abundance and diversity. For instance, in some studies, the abundance of perennial weeds was doubled under reduced tillage intensity. In addition, higher values of Shannon-Weiner and Pielou indices were reported in the PK fertilization treatment compared to the control and NK fertilization treatments. The objective of this paper is to provide a brief overview of the key results of these experiments and summarize the part of the literature related to the effect of tillage systems and fertilization on weed species abundance and diversity. Such knowledge could contribute to the sound design and implementation of integrated weed management programs which in turn may lead to a decrease in the density of serious and noxious weeds and an increase in the overall balance of agroecosystems.