Medicinal and Aromatic Plant Research

Transcription

1 Medicinal and Aromatic Plant Research Objective 3. Improved agronomic practices for milk thistle 2004 PREPARED BY: D. WATERER J. BANTLE P. HAGEL FUNDED BY: AGRICULTURE DEVELOPMENT FUND Department of Plant Sciences University of Saskatchewan, 51 Campus Drive Saskatoon, Saskatchewan, Canada, S7N 5A8 Telephone: (306) Fax: (306)

2 Medicinal and Aromatic Plant Research Program Background Production and processing of spice crops and medicinal herbs represents a potential bright spot in the future of Saskatchewan=s agricultural sector. Saskatchewan growers have established a worldwide reputation as cost-competitive suppliers of superior quality medicinal plants and spices. Based on present growth rates, the Saskatchewan Herb and Spice Association (SHSA) projects the value of primary production of Saskatchewan-grown herb and spice products will approach $ 200 million annually by Numerous opportunities are available to add further value to these crops through processing, blending, preservation, extraction, encapsulation and packaging. A number of Saskatchewan companies have seized these opportunities, resulting in significant employment and economic activity in both urban and small town settings. The marketplace for medicinals and spices is demanding, rapidly changing and highly competitive. To stay viable, Saskatchewan=s herb and spice sector must focus on the best crops, varieties and production practices available. Emerging threats such as disease must be identified and dealt with effectively, but in a manner that does not jeopardise Saskatchewan=s reputation for producing a safe, quality product. This project takes a multi-disciplined approach to address the key production challenges for cumin and milk thistle under the relatively short and cool growing conditio in Saskatchewan. Production of these crops in Saskatchewan is presently limited by challenging growing conditio and specific agronomic problems. This project aims to alleviate these problems by crop improvement and development of superior agronomic practices. Although improvement of spice/medicinal crops is possible utilizing standard plant breeding methods - the process is slow and coequently expeive. Double haploid technology allows the creation of a genetically homogeneous population without the need for multiple generatio of selfing. This has the potential to greatly accelerate progress in improvement of medicinal/aromatic plants. Program Objectives 1) Introduction/development of new/improved lines of cumin and milk thistle by: a) accessing and evaluating potentially suitable material from public and private sources. b) working with breeders from the Crop Development Center of the University of Saskatchewan to further develop adapted crop lines. 2) Pathology support to reduce losses to disease in cumin: Blossom blight has decimated previous plantings of cumin in Saskatchewan. a) Agronomically superior lines of cumin identified under Objective #1 will be evaluated for disease seitivity in a disease nursery previously established by the Dept of Plant Sciences. b) An integrated disease management approach will be developed, involving selection of resistant lines, identification of preventative production practices and evaluation of chemical control optio. 3) Agronomy of Milk Thistle: a) Time of seeding, seeding rate and row spacing effects on growth, yield and quality characteristics. b) Optimizing nitrogen and phosphorus application rates. c) Comparing organic products to standard chemicals for desiccation of the crop. 4) Field performance of new lines of spice/medicinal crops created using double haploid technology: a) To evaluate lines of dill, fennel, anise, and cowcockle created by PBI/NRC using double haploid technology. b) to compare the performance of the double haploid lines to parental lines

3 Objective 3. Improved agronomic practices for milk thistle. A group of flavenoids called silymari represent the medically valuable compounds sought after in milk thistle. Silymari have been demotrated to both protect and alleviate problems with liver and kidney function. Silymari are present throughout the milk thistle plant, but occur at the highest concentration in mature seed. By comparison, immature seed contai relatively little silymarin. Coequently, the timing of seed harvest is critical. However optimum harvest timing is complicated by the fact that; a) milk thistle is a late maturing plant with an indeterminate flowering habit. b) milk thistle is prone to shattering once the seeds are mature At present, milk thistle is harvested by hand-cutting each seed head as it matures. This process is slow and costly, particularly as the plants sport very large and sharp thor. Saskatchewan growers are struggling to effectively compete with other potential suppliers of milk thistle who have access to more available and affordable sources of hand labor. Once-over mechanical harvest of milk thistle is possible but yields can be less than 50% of those achieved by hand harvesting (Wahab 2002). The quality of the resulting crop is also poor as the once over harvest combines mature and immature seeds. The practical and economic viability of mechanical harvesting milk thistle may be improved if...; a) lines of milk thistle with more uniform flowering habit are identified. This objective was addressed in the germplasm evaluation component of this report. b) agronomic practices are identified that enhance uniformity of crop development and flower maturity c) pre-harvest desiccation is used to accelerate and synchronize maturity of the flower heads. In 2003 and 2004, several studies were conducted to help identify cost-effective production practices and harvest strategies for milk thistle under Saskatchewan growing conditio.

4 Study I Objective: Determine the effects of seeding rate and row spacing on yield and quality of vinegar-desiccated milk thistle grown on dryland. Background : Varying between and within row spacings can influence the rate and nature of development of a crop. Spacing treatments that increase the severity of plant to plant competition within the crop, tend to accelerate and synchronize development of the crop. Environmental stresses such as drought may also accelerate development of some crops while increasing the concentration of secondary metabolites. These respoes would be useful in addressing the fact that in Saskatchewan, milk thistle tends to be uneven and late maturing with relatively low concentratio of active ingredient. Chemical dessication is widely employed as a mea to accelerate and synchronize the readiness of a crop for harvest. Desiccants like Reglone or Roundup applied to milk thistle 7-14 days prior to the target harvest date facilitated mechanical harvest (Wahab 2002). However, organic certification is the norm in production of medicinal plants. Vinegar (acetic acid) is approved for use in organic production to achieve non-selective wed control, either prior to planting or between the rows in organic systems. This study was designed to determine if vinegar has the potential to serve as a crop desiccant in milk thistle. Treatments: Seeding rate: 25, 50, 75,100, 125, 150 seeds / m 2 Row spacing: 20, 60 cm (8, 24 in.) Vinegar application rate: 14% vinegar applied 400 l/ha Experimental design: 6 x 2 factorial in a RCBD with four replicatio Methodology: Seed source: Richters Plot dimeion: 2.44 m x 3.66 m (4' x 12').. Seeding depth: cm (1" - 1.5") Seeding date: May 3, 2003 Desiccation date: September 3 (early) and September 12, 2003 (late) Harvest date: September 19, 2003 Sprayer: High clearance sprayer Harvester: Wintersteiger plot combine Post harvest: seed dried at 35 c in forced air drier Seed cleaning: Dockage tester Results Vinegar (14% vinegar applied 400l/ha) was not an effective desiccant for milk thistle. Even at 16 days after desiccation the plants were not sufficiently dry for efficient machine harvesting. During the 16 day dry-down period, there was a significant loss of seed to shattering. By contrast, adjacent plots treated with Reglone (diquat) were ready for harvest within 3 days of the initial treatment. This rapid dry down both facilitated harvest and reduced shattering loss. The concentration and rate of vinegar used was based on recommendatio provided by Tom Wolfe (AAFC Saskatoon). These rates had been effective in other crops and cropping situatio - but milk thistle appears to be too vigorous for this treatment to work effectively. Growing conditio following application of the desiccant in 2003 also favored

5 continued crop growth. The need for large volumes and multiple applicatio of vinegar suggest that this method of desiccation will be costly as well as only marginally effective. Milk Thistle is typically planted in rows 60 cm or more apart to allow between row cultivation. In-row spacings recommendatio are highly variable. This study examined the impact of increasing the plant population on crop development and yields. Plant populatio as influenced by in and between row spacings had no obvious impact on the rate of crop development, the oet of flowering or seed yields (Table 3.1). This suggests that these variables are more strongly influenced by environmental conditio than by access to resources. As seed of milk thistle is large and relatively expeive, a low seeding rate would make economic see if it also produced a reasonable yield. Table 3.1. Seeding rate and row spacing effects on seed yield for milk thistle desiccated with vinegar Seed yield (kg/ha) Seeding rate 20 cm row spacing 60 cm row spacing Mean 25 seeds/m seeds/m seeds/m seeds/m seeds/m seeds/m Mean Analysis of variance Source: Seeding rate (R) Row spacing (S) R x S C.V. (%) indicates non-significant treatment effects. 22.3

6 Study II Objective: Determine effects of nitrogen and phosphorus fertilizers and the time of desiccation on yield and quality of milk thistle Background: Access to abundant nutrients may increase overall crop growth but can potentially delay maturity. The impact of nutrient supply on quantity and quality of medicinally active compounds is largely unknown. In production of milk thistle, nutrient regimes must balance the benefits of increasing total yield potential with the potential drawbacks of slowing crop development and/or negatively affecting medicinal quality. When using chemical desiccants to terminate crop growth, growers must get the timing right. Desiccating too early sacrifices yields, but if the grower waits too long, environmental conditio may no longer be suitable for the desiccants to work and/or the crop may begin to shatter out. Treatments: Nitrogen rate: Phosphorus rate: Desiccation timing: Desiccant: 0, 50, or 100 kg N/ha 0, 60, or 120 kg P 2 O 5 /ha Early, Late Reglone (2.7l/ha in 1000 l water/ha) Experimental design: 3 x 3 factorial in a RCBD with four replicatio for the two harvest dates Methodology: Seed source: Richters Plot dimeion: 2.44 m x 3.66 m (4' x 12').. Seeding depth: cm (1" - 1.5") Seeding date: May 3, 2003 Desiccation date: September 2, 2003 (Early desiccation) and September 15, 2003 (Late desiccation) Harvest date: September 5, 2003 (Early desiccation) and September 19, 2003 (Late desiccation) Sprayer: High clearance sprayer Harvester: Wintersteiger plot combine Post Harvest: Dry seed at o C in forced air drier Seed cleaning: Dockage tester seed dried at Progress: High levels of N (100 kg/ha) appeared to negatively affect stand establishment - likely due to salt burn. This reduced seed yields. None of the other nutrient treatments had any obvious effects on the rate of crop development, crop vigor, timing of flowering, seed yields (Table 3.2) or the silymarin content of the seeds (Table 1.4). Fertility treatments also did not influence the crop s seitivity to chemical desiccants. The crop was growing vigorously on Sept 2 - the date of the first top killing treatment. About 10% of the seed heads had opened at that time - but no shattering had occurred. Growing conditio from that point through to when the other treatments were desiccated (Sept 15) were also excellent, with no frost. Warm weather conditio following application of the Reglone desiccant caused quick dry-down of the crop, enabling combining within three to four days of the initial treatment. Any further delay in combining

7 after desiccation would not be desirable due to increasing losses to shattering. The additional growth period between Sept 2 and Sept 15 resulted in a 40% increase in seed yields. Table 3.2. Nitrogen and phosphorus rate effects on milk thistle seed yield when desiccated with Reglone at two different times Seed yield (kg/ha) Treatment Early desiccation Late desiccation Mean Nitrogen (kg N/ha) Phosphorus (kg P2O5/ha) Mean Analyses of Variance Source: Nitrogen (N) Phosphorus (P) N x P ***(166) ***(230) C.V. (%) *** and indicate significance P<0.001 level of probability and not significant respectively. Values within parentheses are LSD estimates at 5.0% level of probability.

8 Study I Objective: To test the effects of nitrogen, phosphorus, and desiccation timing on yield and quality for organically and non-organically desiccated milk thistle grown on dryland. Treatments: Nitrogen rate: Phosphorus rate: Standard Desiccant: Organic desiccant: Desiccation timing: 0, 50, 100 kg N/ha 0, 60,120 kg P 2 O 5 /ha Reglone, 1000 l water/ha) Vinegar (14% 1000 l water/ha application rate) 30% and 60% mature flower head stage Experimental design: 3 (nitrogen rate) x 3 (phosphorus rate) factorial with four replication. Separate tests for the different desiccation dates and desiccation methods (i.e. four tests in total) Methodology: Seed source: Richters Plot dimeion: 2.44 m x 3.66 m (4' x 12'). Seeding rate: 100 seeds/m 2 Seeding depth: 1-2 cm Separate tests sufficiently so that it will not hinder spraying operatio. Desiccation: Harvest : Post Harvest : Seed cleaning: As per treatment Winterstieger plot combine Dry seed at o C in forced air drier Dockage tester Observatio: Plant stand count Growth (height, branching etc.), ground cover, flowering, maturity Desiccation efficiency Seed Yield Seed quality based on color analysis 100 seed weight Silymarin content of mature and immature seed Spring soil analysis (0-30 cm depth) Results Seeding date: May 14, 2004 Desiccation: Reglone 30% fluff - September 7, 2004 Reglone 60% fluff - September 15, 2004 Vinegar 30% fluff - September 8, 2004 Vinegar 60% fluff - September 15, 2004 Harvest: September 24, 2004 In-season rainfall: 290 mm

9 Discussion The data indicates no significant yield respoe to applied N or P (Table 3.3). A similar lack of fertility respoe was observed in the 2003 trial. It should be noted that this trial site has fairly high levels of residual fertility. This may reduce fertilizer respoiveness, particularly for plants like milk thistle which have not been exteively selected for yield respoe to fertility. Seed yields for the Reglone treated plots were significantly higher than for the plots desiccated with vinegar. This may reflect increased shattering out during the more protracted drying period required when vinegar was used as the desiccant. For both desiccants, the later treatment date (60% fluff) resulted in substantially higher yields. A similar beneficial yield respoe to delaying desiccation was observed in As the silymarin content of the seeds also increases with seed maturity, delaying desiccation as long as possible would seem to be highly desirable - if problems with excessive shattering losses can be avoided. Table 3.3. Effects of nitrogen and phosphorus application on seed yield of milk thistle when desiccated at two different stages using Reglone or vinegar Reglone Vinegar Treatment 30% fluff 60% fluff 30% fluff 60% fluff Mean Seed yield (kg/ha) N rate (kg/ha) P rate (kg/ha) Mean Analyses of variance Source Nitrogen (N) Phosphorus (P) N x P C.V (%) 7.7% 13.0%

10 Study Objective: To test seeding rate and row spacing effects on yield and quality for milk thistle grown on dryland. Treatments: Seeding rate: 25, 50, 75,100, 125, 150 seeds / m 2 Row spacing: 20, 60 cm (8, 24 in.) Experimental design: 6 (rate) x 2 (spacing) factorial in a RCBD with four replicatio Similar tests for spring and fall seeding Methodology: Seed source: Richters Plot dimeion: 2.44 m x 3.66 m (4' x 12').. Seeding depth: cm (1" - 1.5") Seeder: Fabro seeder. Used large cone for 20 cm spacing and small cone for 60 cm spacing Desiccation : Reglone 1000 l water/ha) when majority of flower heads are ready and before shattering/dispersal. Given a second application after 5-7 days to iure adequate dry-down Harvest : Winterstieger plot combine Post-harvest : Dry seed at o C in forced air drier Seed cleaning : Dockage tester Observatio: Plant stand count Growth (height, branching etc.), ground cover, flowering, maturity Frost damage Seed yield Seed quality based on color 100 seed weight Silymarin content of mature and immature seed In-season rainfall Progress to Date Seeding date: May 14, 2004 Desiccation: September 7, 2004 Harvest: September 24, 2004 In-season rainfall: 290 mm Discussion - Yields were not affected by either seed spacing ( seeds/m) or between row spacing (20 or 60 cm). A similar lack of respoe to plant populatio was observed in the 2003 trial. Milk thistle appears to be a very plastic crop, adapting to the growing space available. As the seed is large and costly, the data suggests that a low seeding rate and wide row spacing would be most economical without compromising yield potential of the crop.

11 Table 3.4. Seeding rate and row spacing effects on milk thistle seed yield Row spacing Seeding rate 20 cm 60 cm Mean Seeds /m Seed yield (kg/ha) Mean Analysis of variance Source Seeding rate (R) Row spacing (S) R x S C.V (%) 10.9