The Effects of Potassium Silicate as a Component of Nutrient Medium for Selected in Vitro Cultures of Prunus and Corylus Genera

Even though silicon is frequent compound in soil, its use in plant nutrient media is rare. Based on known physiological role and up to now performed studies it seems that silicon has a good potential to improve growth characteristics of in vitro cultivated plants. Before practical application, however, it is always necessary to assess the optimal conditions of application with regard to the fact that plant reactions to different chemicals added to nutritional media can vary on the species or even cultivar level. The presented study evaluate effects of potassium silicate used in in vitro cultivation media on growth parameters of Prunus persica x Prunus davidiana 'Cadaman,'Prunus x amygdalopersica 'GF 677'and Corylus avellana 'Tonda di Giffoni'genotypes, which are frequently subject of commercial in vitro multiplication. In fact, four different concentrations of potassium silicate was added to the multiplication media, control medium was left silicon-free. Three different characteristics were observed during cultivation - number of new shoots per explant, weight of a new plant and length of new shoots, from which number of new shoots per explant was considered the most important factor. In all cases a positive effects of potassium silicate on the condition and other growth parameters of treated cultures were observed. In 'Cadaman'culture significant growth changes appeared on media with 20 mg.l-1 potassium silicate, which can be recommended for future applications. For 'GF 677'the best results were obtained on media with 2 mg.l-1 which can be recommended for improving condition and number of shoots on new plants. For hazelnut genotype 'Tonda di Giffoni'best results were obtained on media with 10 mg.l-1 of potassium silicate, but also use of 5 mg.l-1 of potassium silicate significantly improved growth parameters. Generally, presented study provides important and practically useful insights into the practical use of silicon in cultivation media designated for commercial in vitro micropropagation.O

Rainfall and temperature influence expression of foliar symptoms of grapevine leaf stripe disease (esca complex) in vineyards

Two vineyards in the Abruzzo Region, central Italy, affected by grapevine leaf stripe disease (GLSD), were monitored for incidence and severity of foliar symptoms of the disease for 21 consecutive years (1994 to 2014). Each year, rainfall and temperature were recorded. Correlations between symptom incidence or severity and rainfall or temperature of different periods of the year or single months were assessed. July rainfall and temperature were highly correlated with incidence and severity of leaf symptoms. The vineyards were characterized by high longevity, vigour and yields, and a particular dynamic of GLSD. In the period following 2005, the year of peak vine mortality, there was a decrease of the expression of foliar symptoms, which was not correlated with both of the climate parameters. Greater mortality occurred for vines showing severe symptoms at the first appearance of GLSD than for vines with low severity

Incidence of symptoms and fungal pathogens associated with grapevine trunk diseases in Czech vineyards: first example from a north-eastern European grape-growing region

Grapevine trunk diseases (GTD) are one of the most important constraints for grapevine and wine production worldwide. Most of the published studies on these diseases in Europe relate to the major vine growing regions mainly located in southern Europe. This is the first study of GTD incidence and associated fungal pathogens in Czech vineyards, as an example of the north-eastern European grape-growing region. Annual incidence of GTD symptoms in vineyards of cvs. ‘Chardonnay’ and ‘Cabernet Sauvignon’ in three Czech locations was surveyed. On average, 3.7% of the ‘Chardonnay’ plants showed GTD symptoms and 0.7% suddenly collapsed each year. Within the ‘Cabernet Sauvignon’ vineyards, 10.1% of the plants showed GTD symptoms and 2.5% suddenly collapsed. Several fungal pathogens were associated with the suddenly collapsed grapevines, and the most frequent was Phaeomoniella chlamydospora (77% of analyzed grapevines), followed by Eutypa lata (62%), Diaporthe ampelina (31%), Botryosphaeria dothidea (15%) and Fomitiporia mediterranea (15%)

The change of bacterial spectrum after storage of X. Campestris pv. Campestris Inoculated Cabbage Heads (Brassica oleracea var. Capitata L.)

Changes in the bacterial spectrum of cabbage heads after storage under commonly used storage conditions were examined in this study. Cabbage seeds (Brassica oleracea var. capitata L.) were artificially inoculated with X. campestris pv. campestris (Xcc), a serious pathogen of cruciferous plants causing black rot. Isolation of bacterial cultures from Xcc-inoculated and non-inoculated cabbage heads were carried out in two time points-at the day of harvest and after four months of storage. According to our previous research and literature reports, the most frequent genera of bacteria were chosen for PCR testing, i.e., Bacillus cereus group, Bacillus subtilis group, Pseudomonas sp., and X. campestris pv. campestris. A few of the obtained bacterial cultures were negative for the four above-mentioned species. In those, other bacteria were identified by 16S rRNA sequencing. In both Xcc-inoculated and non-inoculated cabbage heads, changes of the bacterial spectrum over time were observed. The severity of Xcc infection of heads increased after four months of storage. Bacillus species represented the most frequently occurring bacterial genus. The presence of the Bacillus subtilis group increased significantly after storage in non-inoculated cabbage heads. The minor part of the other genera identified by sequencing in the first sampling were not detected in the stored cabbage heads. This was associated with a possible antagonistic behavior of Pseudomonas sp. and Bacillus sp.O

Interaction of the Nanoparticles and Plants in Selective Growth Stages—Usual Effects and Resulting Impact on Usage Perspectives

Nanotechnologies have received tremendous attention since their discovery. The current studies show a high application potential of nanoparticles for plant treatments, where the general properties of nanoparticles such as their lower concentrations for an appropriate effects, the gradual release of nanoparticle-based nutrients or their antimicrobial effect are especially useful. The presented review, after the general introduction, analyzes the mechanisms that are described so far in the uptake and movement of nanoparticles in plants. The following part evaluates the available literature on the application of nanoparticles in the selective growth stage, namely, it compares the observed effect that they have when they are applied to seeds (nanopriming), to seedlings or adult plants. Based on the research that has been carried out, it is evident that the most common beneficial effects of nanopriming are the improved parameters for seed germination, the reduced contamination by plant pathogens and the higher stress tolerance that they generate. In the case of plant treatments, the most common applications are for the purpose of generating protection against plant pathogens, but better growth and better tolerance to stresses are also frequently observed. Hypotheses explaining these observed effects were also mapped, where, e.g., the influence that they have on photosynthesis parameters is described as a frequent growth-improving factor. From the consortium of the used nanoparticles, those that were most frequently applied included the principal components that were derived from zinc, iron, copper and silver. This observation implies that the beneficial effect that nanoparticles have is not necessarily based on the nutritional supply that comes from the used metal ions, as they can induce these beneficial physiological changes in the treated cells by other means. Finally, a critical evaluation of the strengths and weaknesses of the wider use of nanoparticles in practice is presented

Rainfall and temperature influence expression of foliar symptoms of grapevine leaf stripe disease (esca complex) in vineyards

Summary. Two vineyards in the Abruzzo Region, central Italy, affected by grapevine leaf stripe disease (GLSD), were monitored for incidence and severity of foliar symptoms of the disease for 21 consecutive years (1994 to 2014). Each year, rainfall and temperature were recorded. Correlations between symptom incidence or severity and rainfall or temperature of different periods of the year or single months were assessed. July rainfall and temperature were highly correlated with incidence and severity of leaf symptoms. The vineyards were characterized by high longevity, vigour and yields, and a particular dynamic of GLSD. In the period following 2005, the year of peak vine mortality, there was a decrease of the expression of foliar symptoms, which was not correlated with both of the climate parameters. Greater mortality occurred for vines showing severe symptoms at the first appearance of GLSD than for vines with low severity