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Augustinová L., Doležalová J., Matiska P., Wimmerová Z., Kodetová T. Over the course of [2007][2008][2009][2010][2011][2012][2013] 19 selected cultivars of Chrysanthemum × grandiflorum were tested. Testing was conducted during two seasons under field conditions and on potted plants in the freezing chamber at temperatures -8, -10 and -12°C. It was found that frost hardiness of chrysanthemums of Multiflora type can be reliably determined at a temperature intervention of -8°C. The field trials and tests in freezing chamber revealed that cv. Vlasta did not overwinter. In field trials, the most winter hardy cultivars were Zina, Berta, Mína, Dorota, Estela, Tereza and clone 912, which are possible to grow as short-lived perennials. Cvs Marika and Tereza showed the best frost resistance in the freezing chamber and the best survival results after simulating spring frost.

The aim of this work was evaluation of 24-epibrassinolide influence on yield and quality of head lettuce in optimal and reduced moisture conditions and work out recommendation of 24-brassinosteroids use for lettuce in growers praxis. Field trials were carried out on land belonging to the Demonstration and Research Station of CULS in Prague – Troja in 2009 and 2011. Planting on 27. 8. 2009 and 20. 8. 2011 was done at planting space 0.25 × 0.30 m, each variant in four repetition (single plot 4,5 m2). Seedlings of head lettuce (cultivar Santoro – Rijk Zwaan) were used. Irrigation was carried out by microspraying, and was based on current values of efficient water capacity (EWC); the critical value of the EWC was 80% for optimally irrigated fields (irrigation O), and 50% for variants with reduced levels of irrigation (irrigation S). The total amount of irrigation water during vegetation were as follows: the variant with optimal levels of irrigation (O) had 131 mm in 2009 and 123 mm in 2011; the variant with reduced levels of irrigation (S): 58 mm in 2009 and 63 mm in 2011 Three variants were in both (O and S) conditions: A – no application of 24-epibrassinolide, B – 1 × 24-epibrassinolide application immediately after planting, and C – application of 24-epibrassinolide 2 x (immediately after planting and then after 14 days after 1st application). Concentration of 24-epibrassinolide was 10−6. Following parameters of head lettuce were set after harvesting (10.–12. 10. 2009 and 14.–15. 10. 2011): weight of single heads, marketable heads, marketable yield (in pcs/ha and t/ha) and ascorbic acid and nitrate contents. Influence of 24-epibrassinolide on single lettuce head weight was not significant, decrease of head weight was evident after 24-epibrassinolide application in some variants. Significant increase of marketable heads number and their percentages were noted after 24-epibrassinolide application in optimal moisture conditions – in variant B of 12 261 heads/ha (11.1 %) and in variant C of 16 279 heads/ha (14.7 %) compared with non treated variant A. This trend was not visible in reduced moisture conditions. Increase (nonsignificant) of total marketable yield (in t/ha) was noted after 24-epibrassinolide application. No significant differences were founded among the ascorbic acid contents in each irrigation variant. A higher ascorbic acid content (by approximately 11.9 % in variant C compared with control A) is evident after application of 24-epibrassinolide in the variant with lower levels of irrigation – S. Contrarily, decrease ascorbic acid content is indicated in the optimal levels of irrigation – O (by approximately 16.8 % in variant C compared with control A). The influence of 24-epibrassinolide application on the nitrate content was not significant, but the trend of nitrates decrease in optimal irrigation conditions is evident.

The field experiments described here were conducted over a period of three years. The effect of mulching on emergence, phenophase, the weight of single fruits and yield of the ‘Elisabet F1’ and ‘Harriet F1’ cultivars of gherkins were evaluated, using wheat straw, black non-woven fabric and Ekocover paper mats as mulch compared to a non-mulched control variant. A positive effect of mulching on emergence was found using non-woven fabric at a reduced level of irrigation. The use of non-woven fabrics (21.01 t/ha) and wheat straw (22.92 t/ha) as mulch positively affected yield compared with the non-mulched variant (20.97 t/ha). Reduced levels of irrigation positively influenced the representation of market fruit compared to optimum levels of irrigation (about 1.5 to 3.1%), but these fruits were lighter (about 0.5 to 2.0 g). The influence of the cultivar on the evaluated properties of gherkins was insignificant. Higher yield (9%) and a higher percentage of market fruit (about 0.8 to 2.0%) was found for the ‘Harriet F1’ compared to ‘Elisabet F1’.