Influence of seaweed extract (Ecklonia maxima L.) applied with tebuconazole on two cultivars of winter rape.

Summary Field experiments were carried out in the years 2008-2010 in the Institute of Plant Protection – National Research Institute in Poznan (Poland). The experiments were established on two population cultivars of winter oilseed rape: ‘Californium’ and ‘Monolit’, in 4 replications, using randomized block design. The aim of the study was to assess the influence of tebuconazole (Brasifun 250 EC) and marine algae extract (Kelpak SL) applied separately or in the mixture on plants of two winter oilseed rape cultivars. Kelpak SL was used once or twice, in different growth stages of the crop. A mixture of the both examined preparations was applied only in one growth stage of winter oilseed rape. The effect of tebuconazole, marine algae extract and the mixture of the both substances on winter rape plants was much more determined by weather conditions of plant vegetation than by the cultivar factor. The mixture of tebuconazole and algae, similarly as algae alone, did not influence plant height. Only tebuconazole applied separately showed a growth retardant effect on winter oilseed rape. In the mixture the retardant effect of tebuconazole was inhibited by the addition of algae extract. All the experimental combinations were characterized by a greater leaf chlorophyll content. The examined substances applied separately or in a mixture considerably increased crop yielding.