Effect of the date and harvest method on the yield and quality of milk thistle (Silybum marianum L. Gaertn.) cultivated on light soil



Over 2004–2006 at the Agricultural Experiment Station at Mochełek (University of Technology and Life Sciences in Bydgoszcz), there was evaluated the effect of harvest methods and dates on the yield and quality of fruit (achene) of milk thistle cultivated on light soil. A two-stage harvest was applied when 30% of inflorescences had pappus and one-stage harvest when 30 or 50% of inflorescences developed the pappus. The highest fruit yield (1.43 t.ha-1) was recorded from the one-stage harvest when 30% of the flower heads were ripe. A delay in the one-stage harvest resulted in an increase in the content of silymarin (from 2.5 to 2.7%) but in a decrease in the fruit yield to 1.17 t.ha-1 that was comparable with the two-stage harvest (1.09 t.ha-1). At an earlier ripeness stage (30% of inflorescences with pappus) the content of silymarin was negatively correlated with the share of the pericarp in the achene weight as well as with the achene yield. The harvest dates and methods resulted in differences in the silymarin yield from 27.3 (two-stage harvest) to 35.6 kg.ha-1 (earlier one-stage harvest).
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