A polyfactorial field experiment was established and investigated during vegetation periods from 2004 to 2007 at the Dolná Malanta locality (Nitra district, Slovakia). The following parameters were measured: (1) yields of milk thistle (Silybum marianum [L.] Gaertn.) achenes, i.e. fruits, in 2004–2007; (2) content of silymarin in dry fruits of milk thistle in 2006–2007; and (3) total yields of silymarin per ha in 2006–2007. Factors of the experiment were as follows: (1) crop residues of cultivated pre-crop (no crop residues – K, with crop residues – R); (2) cultivation of freezing-out intercrop (no intercrop – B, with intercrop – M); (3) fertilization using artificial fertilizers (no fertilization – O, with fertilization – F); (4) year of cultivation (2004–2007). The highest yields of milk thistle fruits were recorded in 2006: from 1,426.5 kg/ha (RBO variant – incorporated crop residues without intercrop, no artificial fertilizers) to 1,832.0 kg/ha (KBF variant – without crop residues, without intercrop and with application of artificial fertilizers). The highest content of silymarin complex in dry fruits of milk thistle was measured in 2007: from 15.14 mg/kg (RMF – with crop residues, intercrop and fertilization) to 20.01 mg/kg (KBO – without crop residues, intercrop and fertilization). The highest total yield of silymarin per ha was recorded in investigated variants in 2006; in variant without crop residues it ranged from 16.45 kg/ha (KMF – with intercrop, with fertilizers) to 24.62 kg/ha (KMO – with intercrop, no fertilization).
Experimental Paper. The effect of colour grading of milk thistle (Silybum marianum (L.) Gaertn.) seeds on their quality for sowing