Effect of temperature on the growth of broccoli (brassica oleracea l. var. italica plenck) cv. fiesta

Summary Three-year studies on the influence of temperature on vegetative growth and growth of broccoli heads (Brassica oleracea var. italica cv. Fiesta) were carried out at the Experimental Station “Marcelin” of Poznań University of Life Sciences in Poland. The relationship between temperature sum day-degree, number and area of leaves as well as head diameter was estimated. Likewise relationship between number and area of leaves and head diameter was established. The correlations were described using linear, curvilinear and segment linear regression. The relationship between temperature sum day-degree and number of leaves was linear, whereas the correlation between temperature and area of leaves and head diameter was curves function. On the basis of segment linear regression it was found that in the period when slow growth of heads was observed (the size of up to about 1.5 cm), the area of leaves increased the fastest. It occurred between the 24th and 27th day after planting. The fastest growth of broccoli heads was noted, when the plant had about 18 leaves and area 4900 cm2. In the period of rapid head growth, the increase of sum temperature of 100 day-degree resulted in head diameter increase by 3.5 cm.

Detection of Arbuscular Mycorrhizal Fungi in the Roots of Strawberry Plants Fertilized with Organic Bioproducts

Summary In organic farming, mineral fertilizers are replaced by various preparations to stimulate plant growth and development. Introduction of new biopreparations into horticultural production requires an assessment of their effects on the growth and yielding of plants. Among the important indicators of the impact on plants of beneficial microorganisms contained in bioproducts is determination of their effectiveness in stimulating the growth and yielding of plants. Moreover, confirmation of the presence of arbuscular mycorrhizal (AM) fungi in the roots and plant growth promoting rhizobacteria (PGPR) in the rhizosphere is also necessary. In addition to conventional methods, molecular biology techniques are increasingly used to allow detection and identification of AM fungi in plant roots. The aim of this study was identification and initial taxonomic classification of AM fungi in the roots of ‘Elkat’ strawberry plants fertilized with various biopreparations using the technique of nested PCR. Tests were performed on DNA obtained from the roots of ‘Elkat’ strawberry plants: not fertilized, treated with 10 different biopreparations, or fertilized with NPK. Amplification of the large subunit of ribosomal gene (LSU rDNA) was carried out using universal primers, and then, in the nested PCR reaction, primers specific for the fungi of the genera Glomus, Acaulospora, and Scutellospora were used. Colonization of strawberry roots by arbuscular mycorrhizal fungi was determined on the basis of the presence of DNA fragments of a size corresponding to the types of the fungi tested for. As a result of the analyses, the most reaction products characterizing AM fungi were found in the roots of plants treated with the preparation Florovit Eko. The least fragments characteristic of AM fungi were detected in the roots of plants fertilized with NPK, which confirms the negative impact of mineral fertilizers on the occurrence of mycorrhizal fungi in the roots of strawberry plants. The roots of plants fertilized with Tytanit differed from the control plants by the presence of one of the clusters of fungi of the genus Glomus and by the absence of a cluster of fungi of the genus Scutellospora. In the roots of plants treated with other biopreparations there were reaction products indicating the presence of fungi of the genera Glomus, Scutellospora and Acaulospora, like in the roots of the control plants. The results will be used to assess the suitability of microbiologically enriched biopreparations in horticultural production.

The Effect of Cultivar and Biostimulant Treatment on the Carrot Yield and its Quality

Summary Modifications in growing techniques can affect the yield and nutritional quality of various cultivated plants. Among them, the use of biostimulants is environmental friendly method of stimulating crop productivity, stress resistance, and affecting yield or chemical composition of the plants. The aim of the investigation was determining of the effect of biostimulant treatment on yield and its quality of carrot grown for summer harvest. The experiment was carried out in 2009-2011 in the experimental station of the University of Agriculture in Krakow, south Poland. Two experimental factors were taken into consideration: (1) cultivar: Nandrin F1 and Napoli F1 (2) dose of Aminoplant (foliar application): 1.5 and 3.0 dm3∙ha-1 and control (without Aminoplant). Total and marketable yield, root length, its diameter, leaf mass and leaf : root mass ratio were assessed. The dry matter, soluble sugar, carotenoids and nitrate ions contents were analyzed as main determinants of carrot nutritional quality. Aminoplant influenced not only carrot productivity, but mainly chemical composition of the roots. The present results also suggest that carrot reaction to biostimulant treatment was depended on a cultivar more than on environmental conditions in particular growing seasons. The significant effect of Aminoplant in a dose of 1.5 dm3∙ha-1 on the yield of roots and leaf rosette mass of ‘Nandrin F1’ appeared only in the first year of the experiment. Spraying with Aminoplant in a dose of 3.0 dm3∙ha-1 significantly increased the soluble sugars content in carrot roots of both cultivars but only in 2011. Dry matter content was also affected by biostimulant treatment mainly for ‘Napoli F1’, which showed the lowest dry matter content when sprayed with Aminoplant in a dose of 1.5 dm3∙ha-1. In 2010 control plants contained the greater amount of carotenoids, while in next year roots of plants treated with Aminoplant in a dose of 3.0 dm3∙ha-1 had more these compounds. The significant effect of Aminoplant on nitrates content in carrot roots was observed but were not repeatable in the experimental years, so different climatic conditions modified carrot reaction on biostimulant spraying.

Interaction Between Salt Stress and Angular Leaf Spot (pseudomonas syringae pv lachrymans) in Cucumber

Summary We studied the effects of sequentially applied salt stress and Pseudomonas syringae pv lachrymans (Psl) infection in cucumber (Cucumis sativus L.). Infection development, shoot and root growth potential, the concentrations of chlorophyll and proline as well as electrolyte leakage, lipid peroxidation and H2O2 production were determined. Cucumber plants were first exposed to salt stress and irrigated for seven days with 50 or 100 mM NaCl and thereafter inoculated by Psl. Abiotic stress compromised the defence response to pathogen and disease severity was the highest in 100 mM NaCl-treated plants. The reduced performance of salinized plants under biotic stress could be related to salt stressinduced plant growth inhibition with leaf expansion being the most sensitive to salinity, decreased chlorophyll content, increased electrolyte leakage and prolonged H2O2 accumulation in leaves implying perturbations in redox homeostasis. The response of NaCl-treated and control plants to bacterial infection differed in terms of H2O2 generation and lipid peroxidation. This study confirmed that proline is an important component of local and systemic responses to salt stress and infection. The results contribute to our knowledge of the nature of plant response to a combination of abiotic and biotic stresses

Sensory Quality of Carrots from Organic and Conventional Cultivation

Summary The aim of the study was to determine the effect of the cultivation method (organic and conventional) on the sensory quality of carrot roots - fresh, stored, and cooked. The study was conducted in the sensory evaluation laboratory of the Institute of Horticulture in Skierniewice in 2009-2011. The carrot roots came from a certified experimental field with a stable ecosystem, adapted for conducting experiments on the organic growing of vegetables. At the same time, in the same soil and climatic conditions, carrots were grown in the conventional system. The experimental material consisted of two varieties of carrot - Perfekcja and Regulska. In a two-year cycle, sensory analyses were performed of fresh carrot roots, and of roots that had been stored and heat treated. The evaluations were conducted by a 10-person panel of specialists using the method of quantitative descriptive analysis (QDA). The results of qualitative sensory evaluations and the profilograms prepared on that basis for fresh and stored carrot roots indicated differences in the sensory characteristics between the tested varieties grown in organic and conventional systems. The greatest impact on the overall quality was exerted by the attributes: the carrot-taste, sweet taste, juiciness and hardness of the flesh. Organically grown carrots of the variety Regulska were characterized by the highest intensity of sweet taste and the carrot- taste, and by the best hardness, crunchiness, crispness and juiciness of the flesh. Fresh roots of this variety received the highest overall score. There were also some differences in the sensory characteristics of carrot roots after several months of storage, and then after cooking them, depending on the variety and cultivation method. In both years of the study, following the storage period, the cooked carrot roots of the variety Perfekcja from organic cultivation received the highest scores for overall quality. After storing and subjecting carrot roots to heat treatment, there was a significant decrease in the intensity of most of the quality descriptors, such as taste, smell and texture, when compared with the fresh roots under evaluation

The Effect of Storage in Controlled Atmosphere on the Quality and Health-Promoting Components of Broccoli (Brassica Oleracea bar. Italica)

Summary The aim of the study was to determine the effect of storage conditions on the quality and health-promoting components of broccoli. Broccoli heads cv. Marathon F1 were stored at 0°C for 100 days in controlled atmospheres containing: 1) 15% CO2 - 3% O2, 2) 10% CO2 - 3% O2, 3) 8% CO2 - 1% O2, 4) 5% CO2 - 3% O2. In the control treatment, broccoli heads were stored in normal atmosphere in crates lined with PE film. Before and after storage, chemical analyses were performed for the content of ascorbic acid, total sugars and glucosinolates - sulforaphane and indole-3-carbinol. Additionally, after storage the quality of broccoli heads was assessed visually on a 1-10 point scale, and the percentage of marketable heads was determined. The total content of sulforaphane and indole-3-carbinol in fresh broccoli was lower in comparison with stored broccoli. The sulforaphane content in fresh broccoli was about twice as high as that of indole-3-carbinol. Storage in an atmosphere consisting of 5% CO2 - 3% O2 was more favourable in comparison with the other gas concentrations in terms of glucosinolate content. A decrease in the content of ascorbic acid and total sugars during storage was noted in all the treatments. The highest loss of these components occurred in broccoli stored in an atmosphere consisting of 15% CO2 and 3% O2. Broccoli heads stored in normal atmosphere completely lost their market quality due to decay, but the quality of broccoli kept in CA was satisfactory.

A Simple Dual Stain for Detailed Investigations of Plant-Fungal Pathogen Interactions

Summary Dramatic increase in confocal microscopy observation output has been gained by optimization of a simple trypan blue and aniline blue dual-stain and its application to two model pathosystems: Pseudoperonospora cubensiscucumber and Phytophthora infestans-tomato. Comparison of two dual-stain methods for confocal microscopy studies of P. cubensis-challenged cucumber leaves indicated the 'mild' approach most successful. This methodology provides simultaneous detection of different pathogen structures layered with the plant defense reactions. Moreover, ImageJ-assisted quantification of plant defense responses renders this method useful for addressing the host plant resistance reactions, as well as investigating the given isolate's pathogenicity. Application of this method for the P. infestans-challenged tomato leaf samples resulted in detection of several fungal infection structures, along with plant defense responses. The dual-stain also enabled detection of a peculiar aniline blue-sensitive material in the pathogen cell walls at the area of its hyphae emerging through the leaf stomata. Results presented herein indicate this method is applicable for detailed (possibly quantitative) investigations of multiple plant-fungal pathosystems.