Changes in selected production parameters and fatty acid composition of sunflower ( Helianthus annuus , L.) in response to nitrogen and phosphorus applications

ŠKARPA, P., LOŠÁK, T. : Changes in selected production parameters and fatty acid composition of sunfl ower (Helianthus annuus, L.) in response to nitrogen and phosphorus applications. Acta univ. agric. et silvic. Mendel. Brun. , 2008, LVI, No. 5, pp. 203–210 The eff ect of N and P fertilization on the dry matter content, concentration of nutrients (N, P, K, Ca and Mg) and their intake by the plant, production characteristics (achene yields, head diameter, 1000-seed weight, oil content and oil production) and the content of fatty acids (palmitic, stearic, palmitooleic, oleic, linoleic and linolenic) was evaluated in the one-year pot trial with sunfl ower (Helianthus annuus, L.). Nitrogen application had a positive eff ect on dry matter production and increased N intake by plants as early as the beginning of vegetation (4th true leaf). The eff ect of P on dry matter production was not markedly evident until the later growth stage (10th true leaf). At the end of the vegetation period the weight of plants of variants fertilised with N only and variants where P was applied evened out. Achene yields, head diameters, 1000-seed weight, oil content and oil production increased statistically signifi cantly a er N application. Of all the monitored characteristics the increased level of P in the soil aff ected only the 1000-seed weight. The application of both nutrients did not signifi cantly change the content of fatty acids. N fertilization, P fertilization, achene’s yields, head diameter, 1000-seed weight, oil content, fatty acids Sunfl ower plays an important role in crop rotations in the Czech Republic. It is a traditional crop and has a high genetic potential with yields of as much as 5 tons per hectare, which ranks it among traditional oil crops. Although we see year-on-year fl uctuations in the cultivation areas in the Czech Republic, in terms of sunfl ower they are gradually increasing. Also the increasing hectare yields are an important factor. Sunfl ower is one of the main thermophile oil plants (LAGRAVÈRE et al., 2004; ZUBILLAGA et al., 2002) and its importance is growing in view of the climate development, both in the Czech Republic and, in particular, on a global scale. Growing sunfl ower is all the more justifi ed because it is a convenient crop and can be used as a substitute crop a er ploughing back frost-killed winter crops on whole areas. A number of agricultural measures must be carried out when growing sunfl ower; important is plant nutrition based on the rational use of fertilisers, which increase the soil supply of nutrients, at the same time avoiding any negative impacts on the sustainability of the agricultural production system. A good supply of nutrients in the soil is one of the basic prere qui si tes of economically eff ective yields of high qua li ty. Nitrogen plays an important and ir re pla ceable role as a limiting factor infl uencing sunfl ower production (ÖZER et al., 2004; ZUBILLAGA et al., 2002). Nitrogen fertilisation contributes namely to the production of biomass, it increases achene yields and oil production (RUFFO et al., 2003). N is 204 P. Škarpa, T. Lošák an important nutrient participating in proteosynthesis (PASDA et al., 1991). It is an important component of chlorophyll and is involved in the metabolism of vitamins and other bio-catalytic substances. In terms of yields, phosphorus may be a limiting factor in some soils (ZUBILLAGA et al., 2002). To begin with phosphorus is a component of phospholipids, phosphorylated saccharides and peptides, nucleic acids, adenylates (NAD+, NADP+) and ADP and ATP compounds. Its part in metabolic processes is associated with signal transmission, use and conversion of energy. Both nutrients contribute to the metabolism of plant enzymes important in the bio che mistry of lipid metabolism, which catalyse reactions from acetyl coenzyme A to the fi nal products. In common with other vegetable oils approximately 95–99 % of the fatty acids in sunfl ower are present as triacylglycerols. The objective of the pot trial was to explore the effect of N and P fertilisation on the intake of nutrients and their content in plant matter, on achene yields, head diameter, 1000-seed weight, oil content, oil production and quality of oil in terms of the content of fatty acids in sunfl ower. MATERIALS AND METHODS The one-year pot trial with sunfl ower (Helianthus annuus, L.) was established in the experimental vege ta tion hall of the Department of Agrochemistry, Soil Science, Microbiology and Plant Nutrition of the Faculty of Agronomy, Mendel University of Agriculture and Forestry in Brno in 2006. Soil characteristics In autumn 2005 we fi lled each pot with 11 kg of loamy soil characterised as cambisol (FAO soil ta xono my). One week before sowing the soil was sampled for analysis. Table I gives the basic soil characteristics. We monitored the following parameters: pH (1:5 DM soil:solution of 0.01M CaCl2) and available nutrients (P, K, Ca and Mg) set down for soil extraction with the leaching agent Mehlich 3 (0.015 M NH4F + 0.20 M CH3COOH + 0.25 M NH4NO3 + 0.013 M HNO3 + 0.0005 M EDTA) (1:10 DM soil:extraction agent Mehlich 3) (JONES, 1990). The content of phosphorus from the extract was determined by co lo ri meter (UV/VIS spectrophotometer, ATI Unicam 8625). Potassium, calcium and magnesium were assessed by means of atomic absorption spectrophotometer (AAS) on a Carl Zeiss Jena AAS-30 apparatus. I: Agrochemical characteristics of the soil in mg . kg−1 DM soil pH/CaCl2 Content of available nutrients in mg . kg−1 (Mehlich 3)