Management of Milk Thistle Quality D. Waterer J. Wahab D. Cooper

CDC “New Crops” Research Objective –Assist in the identification and adoption of “New Crops” suited to Saskatchewan –Suitable growing conditions and market opportunities ?? –Industry driven initiative

Milk thistle (Silybum marianum) Annual/biennial Indigenous to c. Asia but naturalized worldwide Long history of medicinal use Hepato-protectant Identified by SHSA as “focus crop”

New Crops Program Milk Thistle Research Objective – determine management practices that maximize yields of high quality milk thistle in Saskatchewan Good seed yields vs. Good quality ?

Milk Thistle Quality Silymarin complex + other bioactive flavenoids Silymarin complex = mixture of isomers Silybinin, silychristine and silydianine

Milk Thistle Seed Quality Minimum of 2% silymarin complex... higher the better. Levels and mixture of isomers under genetic and environmental control. Yields more heritable than quality Small positive correlation between yield and quality

Managing for Maximum Yields... Impact on Quality ? Indeterminent flowering habit = uneven ripening Quality improves with seed maturity Shatters once ripe = lost yields Options Hand harvests (multiple) Machine harvest (once-over)

New Crops Program Milk Thistle Research Germplasm evaluation trials ( ) 30 lines from worldwide sources Assess for agronomic characteristics, seed yields and quality Standard crop management practices Hand vs machine harvested

- Once-over machine harvest = 80% of yields. of multiple hand harvest - Much faster and user friendly.

2004 Milk Thistle Trials

Milk Thistle Trials

Milk Thistle Germplasm Trials Huge genetic variability in yield potential and quality Significant year to year variability in yields and quality … but relative performance of lines is fairly stable. Weak positive correlation between yields and quality Machine harvest is efficient and yields a high quality product

Managing for Maximum Yields... Impact on Milk Thistle Quality ? Fertility –Literature shows minimal impact on either yields or quality –Confirmed by Wahab in SK in 2003 and –Good news for organic growers

Managing for Maximum Yields... Impact on Quality ? Plant Populations –Literature shows minimal impact of population on either yields or quality –Confirmed by Wahab in SK in 2003 and –Good news due to high seed costs -Suggests potential for fall seeding

Managing for Maximum Yields... Impact on Milk Thistle Quality ? Timing of Harvest –Literature shows yields peak with maturity … then decline due to shattering. –Desiccation facilitates harvest … impact on yields and shattering = ??? –Desiccation options Chemical desiccants = not organic Organic desiccants (vinegar) Frost = dependability ? –Wahab tests impact of timing of desiccation and type of desiccant on yields and quality in 2003 and 2004.

Managing for Maximum Yields... Impact on Quality ? Timing + Method of Desiccation Studies –Results vary depending on crop maturity at time of desiccation = growing season effects. –Chemical desiccants work faster than organic options –Fast action of chemical desiccants allows delayed treatment = increased yields and improved quality in short seasons

Other Options for Improving Milk Thistle Quality Seed Grading –Relatively easy to grade for seed size –Can achieve significant improvements in quality (% silymarin) by sizing = blending options. –Color sorting is slower, not as effective and complicated by line to line variability in seed color.

Maximizing Milk Thistle Yield and Quality Conclusions –Germplasm selection is critical Significant genetic variability in yields and quality Line performance is relatively stable across years/sites. –Standard management variables (fertility, plant spacing, irrigation) have little impact on yields or quality –Must time harvest for maximum seed maturity without excessive losses to shattering. –Mechanical harvest does not compromise quality. –Desiccation options vary in efficacy –Potential to improve/standardize quality through post- harvest grading steps.

Maximizing Milk Thistle Yield and Quality Conclusions - with better management and handling practices, significant improvements in yield are possible. - with better management practices... higher and more predictable levels of active ingredients are possible - higher yields and quality at lower cost = crucial in a competitive market