Induction of milk thistle (Silybum marianum L. Gaertn) growth and phytochemicals production by natural stimulants

- Growth criteria of S. marianum were significantly enhanced by chicken manure and yeast extract.
- Both treatments slightly affected the total chlorophyll content, but they enhanced PSII photochemical efficiency.
- Silymarin production had enhanced by chicken manure and yeast extract application.
- Seed yield/plant was increased after application of CM and YE and the increase was directly proportional to the applied doses of CM and YE.
- Amino acids content of yielded seeds showed a significant increment with yeast extract and decreament with chicken manure.

Two field experiments were carried out through 2013/2014 and 2014/2015 seasons in Faculty of Agriculture experimental farm, Tanta University, to investigate the influence of chicken manure (CM) and yeast extract (YE) on Silybum marianum (milk thistle) growth, yield and phytochemical constituents. CM was applied to soil with rates of 0.0, 23.81, 35.71 and 47.62 m3/hectare (ha) and YE was applied after 15 and 75 days of seed sowing, with rates of 0, 25, 50 and 100 g/L as foliar spray. The design of the experiment was as split plot with CM as the main plot. Results indicated that the applied bio-stimulants improved the vegetative traits and seed yield, but without obvious effect on chlorophyll content, though both treatments had resulted in a significant enhancement in PSII photochemical efficiency. Also, both bio-stimulants possessed positive impact on the antioxidant status of seed extracts and silymarin production, as well as the phytochemical constituents. However, these treatments caused a pronounced fluctuation in amino acids profile.

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