Tomislav Vinković

Cytokinin response in pepper plants (Capsicum annuum L.) exposed to silver nanoparticles

ABSTRACT The increasing development of different nanomaterials, such as silver nanoparticles (AgNPs), and their practical use in agriculture and biotechnology has created a strong need for elucidations of biological effects and risk assessments of AgNPs in plants. This study was aimed to investigate AgNPs effects on metal uptake and their biodistribution in pepper plants as well as on morphological parameters and hormonal responses of the isoprenoid cytokinin (CK) family. In addition, the comparison of effects silver form, nanoparticles vs. ionic, has also been examined. To the best of our knowledge, this is the first study describing CK responses in plants exposed to metallic NPs. The obtained results indicate that both AgNPs and Ag+ ions significantly increased total content of Ag+ in pepper tissues in a dose‐dependent manner and affected on plant development by decreasing both plant height and biomass in a similar way. This study evidenced for the first time the role of CKs in abiotic stress in plants caused by AgNPs. The hormonal analysis, conducted by an ultra‐high performance liquid chromatography‐electrospray tandem mass spectrometry, revealed a significant increase in total CKs in the leaves and also highlighted the importance of cis‐zeatin type CKs in plants treated with AgNPs. Our observations suggest potential risks of AgNPs on plant ecosystems upon their release into the environment. Graphical abstract Figure. No Caption available. HighlightsCitrate‐coated silver nanoparticles significantly affected development of pepper.Nano and ionic form of Ag showed similar phytotoxicity effects in pepper plants.Both Ag forms increased total Ag in pepper tissues in a dose‐dependent manner.This is first study establishing the role of cytokinins in abiotic stress in plants.Results indicate possible importance of cZ cytokinins in nanostressed plants.

Influence of biostimulant and substrate volume on root growth and development of scarlet sage (Salvia splendens L.) transplants.

The influence of biostimulant and substrate volume on scarlet sage transplants growth and development was examined in this investigation. There was one cultivar of scarlet sage used in trial which was transplanted in pots of two different volumes. Plants were treated with biostimulant (Radifarm) in concentration of 0.25% or left untreated (control). During the trial, root and aboveground fresh and dry mass were recorded. Treatment with biostimulant and bigger substrate volume showed good results by increasing investigated parameters. Investigation shows how biostimulant application to scarlet sage transplants production improves growth and development of root and aboveground mass which is important for faster plant adaptation to stress during transplanting.

Maize and soybean seed vigour under influence of seed age, seed treatment and temperature in cold stress test

Maize and soybean seed (maize hybrid OS 499 and soybean cultivar Ika originated from Agricultural Institute in Osijek, Croatia) harvested in year 2006 as well as one year old seed (harvested in 2005 and aged in storehouse conditions) were used for the evaluation of seed vigour in germination chamber. Seeds were pretreated with fungicide. Fungicide treatment significantly increased germination rate of maize seed in cold test conditions and constant low temperature. Fungicide treatment of soybean seed significantly enhanced germination only at constant low temperature and aged seed. Biostimulant applicaton did not enhanced germination rate but increased dry matter content in normally developed hypocotyls, both in fresh and aged soybean seed. Proline treatment did not show expected stimulative effect on seed germination.

THE EFFECTS OF LIGHT REGIME AND SUBSTRATE ON FLOWER PRODUCTIVITY AND LEAF MINERAL COMPOSITION IN TWO GERBERA CULTIVARS

This research evaluates the influence of light regime and substrate composition on the flower productivity and leaf macronutrient content of two gerbera cultivars (‘Ruby Red’ and ‘Vino’) grown in a greenhouse. A special emphasis was given to macro-element ratios in gerbera leaf. The results confirm positive influence of supplemental lighting on flower yield in both gerbera cultivars. Also, mixed substrate (coco fiber + rice husks) resulted with higher flower yield. Cultivar ‘Vino’ showed better productivity and significantly lower concentration of nitrogen (N), potassium (K), and magnesium (Mg) as compared to ‘Ruby Red’. The total flower productivity per plant correlated with some of the tested macronutrients in gerbera leaf (N, K, Mg) only in natural light conditions. Among all calculated leaf nutrient ratios, only P/Mg was significantly and positively correlated to flower yield, based on data from both light variants.

Assessment of the influence of different sample processing and cold storage duration on plant free proline content analyses

INTRODUCTION A method which is widely accepted for the analysis of free proline content in plant tissues is based on the use of 3% sulfosalicylic acid as an extractant, followed by spectrophotometric quantification of a proline-ninhydrin complex in toluene. However, sample preparation and storage may influence the proline actually measured. This may give misleading or difficult to compare data. OBJECTIVE AND METHODOLOGY To evaluate free proline levels fresh and frozen strawberry (Fragaria × ananassa Duch.) leaves and soybean [Glycine max (L.) Merr.] hypocotyl tissues were used. These were ground with or without liquid nitrogen and proline extracted with sulfosalicylic acid. A particular focus was the influence of plant sample cold storage duration (1, 4 and 12 weeks at -20°C) on tissue proline levels measured. RESULTS The free proline content analyses, carried out in leaves of Fragaria × ananassa Duch. as well as in hypocotyls of Glycine max (L.) Merr., showed a significant influence of the sample preparation method and cold storage period. Long-term storage of up to 12 weeks at -20°C led to a significant increase in the measured proline in all samples analysed. CONCLUSION The observed changes in proline content in plant tissue samples stored at -20°C indicate the likelihood of the over-estimation of the proline content if the proline analyses are delayed. Plant sample processing and cold storage duration seem to have an important influence on results of proline analyses. Therefore it is recommended that samples should be ground fresh and analysed immediately.

Influence of different nitrogen form application on the incidence of ber and elementary composition of bell peppers

Calcium is a very important nutrient in highly productive growing such as glasshouse-grown sweet pepper, but inadequate Ca supply manifests with clear symptoms, such as, for example, local decay of pepper fruits (blossom-end rot = BER. The aim of this study was to compare the effect of different N forms on incidence of BER, yield and fruit quality of pepper fruits of the Cecil F1 cultivar in the region of East Croatia.

Seed Germination of Some Flower Species Under Influence of Different Light Conditions

The aim of this study was to examine germination energy and seed germination rate of some flower species under influence of different light conditions. Seeds of Zinnia elegans Jacq., Dianthus caryophyllus L. and Callistephus chinensis (L.) Nees that were used in the research were purchased in local store. Experiment was set up in three replicates for each light treatment and each flower species. Petri dishes with seeds were placed in growth chamber under artificial white and blue light under 12hL/12hD photoperiod. Results showed no significant difference in germination energy and total germination of investigated flower species in respect of light. Zinnia seedlings were significantly longer on white light, while Dianthus seedlings were longer on blue light. Both, length and fresh weight of Callistephus seedlings were greater on white light. The absence of significant differences between measured parameters under examined light regimes suggests that germination of Zinnia, Dianthus and Callistephus is not photosensitive.

Growing Pelargonium peltatum and Pelargonium x hortum from Cuttings

Pelargoniums are plants from the family Geraniaceae, and one of the most popular summers flowering species that adorn the balconies and windows of the houses and are present in the market since the 18th century. In Croatia, the most commonly grown are ivy-geraniums (P. peltatum) and zonal (P. zonale) geraniums. They reproduce vegetatively because propagating by seed is expensive and only large horticultural companies can afford growing from seed. Every year new cultivars are produced, but geraniums still have a very simple genotype and are grown very successfully adhering to a few basic rules for their cultivation. The aim of this study with the species Pelargonium peltatum and Pelargonium x hortorum was assessing the effects of the use of hormones to stimulate root growth when planting cuttings to receive plants and monitoring the development of cuttings. Cuttings of two different types of pelargonium were treated with hormone Rhizopon to stimulate growth and rooting. Results showed that hormone therapy has no significant effect on growth of this geranium species. Differences between treated and control seedlings were very small, hormone-treated cuttings had faster growth of its root, although at all stages of measuring the length P. peltatum cuttings was significantly higher compared to the P. x hortorum cuttings (p=0.01).

Influence of K excessive soil and plant supply on Ca deficiency in pepper fruits (Capsicum annuum L.)

One of the biggest challenges for the safe maize production is the yield stability in a wide range of environments with different soil fertility, weather conditions, prevailing pests and diseases as well as cultural practices. In order to achieve it, new hybrids with higher tolerance to biotic and abiotic stress are continuously being created. In order to compare performance of maize hybrids in environments with different levels and types of stress, and relate it to the stalk lodging incidence, we compared performance of 64 maize hybrids obtained by crossing 16 inbred lines with four inbred testers in three different environments. Two environments at same location (Rugvica) differed in crop rotation, and the third environment at location Botinec was considered as dry because of low water capacity of the soil. Mixed models that included all design elements and genetic background of hybrids were used to analyze the effect of lodging on yield in different environments. The results show that stalk lodging had a significant effect on yield, but significant lodging x environment interaction indicates that this effect was rather environment specific.Sweet pepper Istra F1 hybrid was grown in a greenhouse on K rich soil. For evaluation of K antagonism, two K rates (55 and 85 kg ha-1) were applied in a randomized complete block design with four replications. Total number of fruits, total number of BER affected fruits as well as average fruit mass were recorded for each harvest. Fruit and leaf K and Ca content were determined at three plant growth stages (at the stage of the first, third and fifth fruit cluster). Higher K rate gave higher : average fruit mass (169.45 g), total number of fruits per plant (7.95), number of BER affected fruits per plant (3.82), K in leaves (5.44% DM), K in fruits (6.35% DM), but negatively correlated with Ca concentration in fruits (0.57% DM) and leaves (3.24% DM). This resulted in decreased marketable yield of sweet pepper fruits.

Aluminium Toxicity in Maize Hybrids During Germination

The investigation of maize seedlings sensitivity to the toxicity of aluminium in germination stage was performed in controlled conditions in germinator. Tested maize hybrids showed different levels of sensitivity to rising Al concentration as early as in the germination stage, where the main root length was reliable indicator of hybrid tolerance.