Oilseed Rape (Brassica Napus L.) Nutrition by Nitrogen and Phosphorus and its Effect on Yield of Seed, Oil and Higher Fatty Acids Content

Abstract

The effect of phosphorus (P) and nitrogen (N) application on yield, oil and fatty acids content (especially oleic acid, linoleic acid and linolenic acid) in rapeseed was investigated in the field experiment. Also effect of weather conditions was evaluated. The polyfactorial trial was realized in experimental years 2013/2014 and 2014/2015 in terms of agricultural cooperative in Mojmírovce. The experiment was based on three variants of fertilization treatments by the block method in three replications. The size of each block was created by plots with size 600 m2. The first level of treatment 10 was non-fertilized control. The second level of treatment 2U was fertilized by nitrogen in dose 240 kg.ha-1. The third level of treatment 3P was fertilized by the same dose of nitrogen 240 kg.ha-1 and by phosphorus in dose 88 kg.ha-1. The highest average yield 3.9 t.ha-1 was achieved at treatment 3P, where phosphorus was applied. It means statistically significant yield increase by 30% compared to treatment 2U, where no phosphorus was not applied. There was statistically non-significant difference in oil content, in the range of treatments. The content of oleic acid fluctuated from 63.3% to 65.9% and the highest was reached at unfertilized control treatments in both experimental years. The linoleic acid content ranged from 20.3% to 21.2% and content of linolenic acid varied between 6.9% and 8.9%. Application of nitrogen and nitrogen + phosphorus high statistically significant decreased oleic acid content in both experimental years. Opposite effect was observed, where content of linoleic and linolenic acid was high statistically significant increased after nitrogen and nitrogen-phosphorus fertilization. Effect of unequal weather conditions and treatments of nitrogen and nitrogen-phosphorus nutrition can influence the percentage ratio of higher fatty acids composition.