The yield formation of sunflower influenced by temperature and moisture conditions of experimental field | Tvorba úrody slnečnice ročnej vplyvom teplotných a vlhostných podmienok pestovateľskej lokality

Field polyfactorial experiments with sunflower (conventional, medium-late hybrids: NK Brio, Alexandra PR, NK Ferti, NK Alego) were realized on the experimental base of Center of Biology and Ecology of Plants FAFR SUA in Nitra Dolná Malanta. Experimental area is located in corn production region, characterized as warm and slightly dry with mild winter and long sunshine, in altitude 250 m, with brown soil. The influence of both temperature and moisture conditions of experimental area on sunflower yield of achenes (conventional, medium-late hybrids: NK Brio, Alexandra PR, NK Ferti, NK Alego) was observed. Fore crop of sunflower (Helianthus annuus L.) was wheat (Triticum aestivum L). Technological system of sunflower cultivation was realized in accordance with conventional technology of cultivation. The basic fertilization was made by balance method on the base of agrochemical soil analysis for expected yield 3 t per ha. During experimental years the change of inner energy (AU) was evaluated for thermodynamic characteristic analysis (security of the temperature and moisture) and the impact of changes on yield forming with maximal yield (Vmax in 2008) and minimal yield (Vmin in 2009). Achieved value of yield from thermal and precipitation energy introduces concrete energy amount, which is available in given period for concrete amount of yield. From the results follow that the sunflower has got critical thermodynamic phase in the period of months July and August. For the yield formation it is necessary, that input power of precipitation prevailed over the thermal during the months July and August. Achieved results confirmed statistically high significant dependence of the yield on weather conditions. It is necessary to consider potential change of agro technological measures in sunflower cultivation because of large annual variations in climate characteristics.