engleski

The effect of fertilizers on the pests in oilseed rape

The consumption of petroleum products in Croatia and in the world at large is on the rise. It is expected that the consumption of motor fuels will rise because of the rapid development of transportation, while the consumption of fuel for heating will decrease. On the other hand, the production of crude oil will fall from 1.37 million tons in 2000 to 0.6 million tons in 2010, while in 2030 a production of no more than 0.4 million tons of crude oil is forecast. An alternative to mineral fuels is the production of biodiesel from various plant oils, as well as from beef suet and used cooking oils (from households and restaurants). The most important raw materials for the production of biodiesel are oil seed rape (82.82% of the total) and sunflower (12.50%). The production of biodiesel in the world is constantly rising, and the areas of land devoted to oilseed rape and other crops for the production of biodiesel are expanding, which necessarily involves problems of protecting these crops from disease, pests and weeds, as well as of the development of pest-resistance to pesticides (Maceljski and Jelovčan, 2007 ; Jelovčan and Gotlin Čuljak, 2007 ; Jelovčan et al., 2007)). In order to achieve high yields, fertiliser application is of great importance, and yet if it is excessive, it can have a bad effect with respect to the incidence of pests. Hence during this research the objective was to determine the effect of various quantities of fertiliser on the appearance of the weevils Ceutorrhynchus napi and Ceutorrhynchus pallidactylus (Coleoptera: Curculionidae) on oilseed rape. The experiment was set up with the Triangle variety of oilseed rape on the Vinokovščak site (Varaždin, Croatia) during 2008. The investigation was conducted on a 1 hectare plot, divided into three fields. Fertiliser (KAN) was applied to the fields in three different quantities: 150, 200 and 250 kg/ha. During the vegetation period, two visual inspections of the oilseed rape plants were made: on April 20 (BBCH 62-64) and May 37 (BBCH 77-79). Ten plants in four repetitions were taken from each experimental field. The plants were dissected and the number of perforations, lengths of corridors and number of Ceutorrhynchus napi and Ceutorrhynchus pallidactylus larvae were recorded. Statistical analysis of the results showed that there are significant correlations between pest attack and the differing quantities of fertiliser, i.e., that their abundance is greater the higher the amount of fertiliser applied. The data obtained show the need to analyse the total amount of nitrogen in the soil and a fertiliser that corresponds to the real condition of nitrogen in the soil, as well as of the needs of the plant that we are sowing (oilseed rape in this case) for nitrogen.

fertilizers; pests; oilseed rape

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