Published in Scientific Papers. Series A. Agronomy, Vol. LXIII, Issue 1
Written by Adelina GARAPOVA
In the experimental field of the Department of Crop Science at the Agricultural University - Plovdiv during the two harvest years, a field experiment has been conducted. The experiment has been carried out by the method of split-plots in four replications after the predecessor triticale. The effect of two soil nutrition regimes - lower and higher has been investigated (main plots). Five sunflower hybrids, all from the Tribenuron-methyl resistant hybrids group have been studied: P64LE25 (standard); LG 59.580 SX; Subaro HTS; ЕS Arcadia SU and Magma SU. Yield of seeds has been calculated from the harvest plots. The following pseudanthium yield components have been investigated: pseudanthium (head) diameter; density of the head and head harvest index. It has been found out that in both years of the study, the factor soil nutrition had a statistically proven positive effect on the yield of seeds. Soil nutritional regime had a positive effect on the diameter of the head by all studied hybrids. By most of the studied hybrids, the higher nutrient contain in soil results in a higher density of the head, an exception is the Magma SU hybrid. The reason for this negative result is the excessively high effect of the higher soil nutritional regime on the diameter of the head by this hybrid, which cannot be compensated by the higher number of seeds.
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