Submitted to: Association for the Advancement of Industrial Crops Conference
Publication Type: Abstract Only
Publication Acceptance Date: August 28, 2003
Publication Date: August 28, 2003
Citation: GESCH, R.W., FORCELLA, F., SHARRATT, B.S. HARVEST DATE AND METHOD FOR CUPHEA IN THE NORTHERN CORN BELT. ASSOCIATION FOR THE ADVANCEMENT OF INDUSTRIAL CROPS. 2002. ABSTRACT P. 10. Technical Abstract: Cuphea (Lythraceae) is rather unique among plants that grow in temperate climates because its seed storage lipids are primarily composed of medium-chain triglycerides. Semi-domesticated genotypes developed from crossing C. viscosissima x C. lanceolata show good potential for commercial production. Cuphea has an indeterminate growth habit and flowering and seed maturation can occur over a four to eight-week period. Seed capsules that initially form during reproductive phase tend to split at the dorsal surface allowing seed to shatter towards the end of the growing season. Little is known about when or how to harvest present Cuphea genotypes in order to maximize seed yield. The present study was initiated in 2000 to determine the optimum period and method to mechanically harvest Cuphea in west central Minnesota. Cuphea (PSR-23) was sown in 61 cm spaced rows with a Marliss no-till grain drill at a rate of 6.7 kg of seed/ha on May 15 in 2000 and May 10 in 2001. Harvest was conducted at weekly intervals between August 23 and September 21 in 2000 and August 13 and October 23 in 2001. Methods of harvest that were evaluated included wind-rowing, defoliating with paraquat and combining, treating with Roundup and combining eight to fourteen days later and straight combining. Results clearly showed that greatest seed yields were obtained in late September to early October, corresponding with the average time when the first "hard" frost (i.e., -2 deg C or less) in this region occurs. Death and dehydration of plants facilitated by freezing aided seed harvesting. However, freezing also hastened seed shattering. During 2001, harvested seed yield increased almost 2.5-fold between August 31 and October 11 with a hard frost occurring October 6. By October 17, harvested yield declined 63%, likely due to seed shattering. Of the harvest methods evaluated, straight combining with a small grain header, like that typically used for soybean, gave the best results. Initial results indicate that when planted in early to mid May, the best time to harvest Cuphea in west central Minnesota is late September to early October, similar to the time frame used for soybean production in this region. The best mechanical harvesting method appears to be combining with a small grain header.