Cuphea, a western hemisphere genus of some 260 species, has been proposed as a domestic source of medium-chain fatty acids. These fatty acids are used primarily in soap and detergent manufacture and are presently extracted from imported tropical oils or from petroleum. Considerable difficulty in obtaining consistent plant stands with direct seeding has been experienced at two Iowa locations. Trials were initiated in 1987 and continued through 1994 to test various treatments upon seedling emergence of C. laminuligera Koehne, C lanceolata Ait., and hybrid C. viscosissima Jacq. X C. lanceolata. These treatments included planting depths from 1.3 to 6.4 cm, seeing rates of 1.5 to 10 kg ha-1, and soil packing or not. Emerged seedlings from pure live seed planted remained less than 60% with all treatments. Increased seeding depth decreased seedling emergence from 29% to 0. Increased seeding-rate increased the number of emerged seedlings, but significant increases were dependent upon the year. Soil packing significantly increased the number of emerged seedlings in 1994 by 14%. Heavy rainfall immediately after planting caused severe stand-losses in 1989, 1991, and 1993. Additional research on seedling emergence under differing conditions would be necessary prior to commercial planting of Cuphea in Iowa

Roath, W. W.

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Managing Seedling Emergence of Cuphea in Iowa

University of Northern Iowa

Journal of the Iowa Academy of Science: JIAS Volume 105 Number Article 5 1998 Managing Seedling Emergence of Cuphea in Iowa W. W. Roath Iowa State University Let us know how access to this document benefits you Copyright © Copyright 1998 by the Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/jias  Part of the Anthropology Commons, Life Sciences Commons, Physical Sciences and Mathematics Commons, and the Science and Mathematics Education Commons Recommended Citation Roath, W. W. (1998) "Managing Seedling Emergence of Cuphea in Iowa," Journal of the Iowa Academy of Science: JIAS, 105(1), 23-26. Available at: https://scholarworks.uni.edu/jias/vol105/iss1/5 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Journal of the Iowa Academy of Science: JIAS by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu. Jour. Iowa Acad. Sci. 105(1):23-26, 1998 Managing Seedling Emergence of C uphea in Iowa W. W ROATHl USDA-Agricultural Research Service North Central Regional Plant Introduction Station, Agronomy Department, Iowa State Universtiy, Ames, IA 50011 Cuphea, .a western hemi.sphe~e g.enus of some 260 species, has been proposed as a domestic source of medium-chain fatty acids. These fatty aods are ~sed pnm~nly m ~oap a~d. deterge~t manufacture and are presently extracted from imported tropical oils or from pe~roleum. Con~idera~le difficulty m obtammg consistent plant stands with direct seeding has been experienced at two Iowa locations. Tnals were miuated m. 1987 and continu.ed th~ough 1994 to test various treatments upon seedling emergence of C. /aminuligera Koehne, C lanceolata Ait., and hybnd C. vrscosrssrma Jacq. X C. lanceolata. These treatments included planting depths from 1.3 to 6.4 cm, see~mg rates of 1.5 to 10 kg ha-1,_and soil packing or not. Emerged seedlings from pure live seed planted remained less than 60% with all treatments. Increased seeding depth decreased seedling emergence from 29% to 0. Increased seeding-rate increased the number of emerged seedlings, but significant increases were dependent upon the year. Soil packing significantly increased the number of emerged seedlings in 1994 by 14%. Heavy rainfall immediately after planting caused severe stand-losses in 1989, 1991, and 1993. Additional research on seedling emergence under differing conditions would be necessary prior to commercial planting of Cuphea in Iowa. INDEX DESCRIPTORS: Cuphea, new crops, alternative crops, oilseeds, agronomic practices. Certain Cuphea species have been proposed as a domestic source of medium-chain fatty acids (MCFA). These fatty acids are currently extracted from imported tropical seed oils or from petroleum prod-ucts and are used in the manufacture of soaps and detergents and in the preparation of certain special foods (Graham 1989; Thompson 1984). Knapp (1993) proposed that selections from the interspecific hybrid C. viscosissima X C. lanceolata were the most promising germ-plasm for domesticating Cuphea as an oilseed crop. We have been collecting, maintaining, distributing, and enhanc-ing Cuphea germplasm at the USDA-Agricultural Research Service North Central Regional Plant Introduction Station (NCRPIS) in Ames, Iowa since 1986. During this period, we have encountered considerable difficulty obtaining consistent stand-establishment when planting Cuphea seed in the field. Establishing consistent stands of Cuphea has not been a problem under irrigated conditions in the Willamette Valley in Oregon (Knapp pers. comm. 1993). Failure to consistently establish adequate stands is a severe con-straint to developing improved cultivars and to commercialization of Cuphea in Iowa. This is complicated by post-harvest dormancy of some Cuphea species and the requirement of light for germination (Grabe pers. comm. 1986). The trials reported in this paper were designed to create a stand-establishment management system for Cu-phea at Ames, Iowa. METHODS Experiment 1 Seed of Cuphea laminuligera Koehne (accession number LA11, a mixture of accessions PI 534691 and PI 561482, obtained from Dr. S. A. Knapp, Oregon State Univ.) was planted in a seeding-rate, 1 Journal paper No. J-16732 of the Iowa Agriculture and Home Economics Exp. Stn. Mention of commercial brand names does not constitute an en-dorsement of any product by USDA-ARS or cooperating agencies. seeding-depth trial at Ames (Webster clay loam, fine-loamy, mixed, mesictypic haplaquolls) in 1987 and 1988. Seed amounts were ad-justed to plant 1.5, 2.5, 3.5, and 4.5 kg ha- 1 pure-live seed in plots 1.4 X 3 m. Planting depths were 1.9, 3.8, and 6.4 cm in 1987 and 1.3, 1.9, 2.5, 3.2, and 3.8 cm in 1988. A factorial randomized com-plete block design with 4 replications was used. The 1987 trial was planted with three double-disk openers 46 cm apart. These openers are commonly used for planting small grains. The 1988 and subse-quent trials were planted with Acra-Plant V-Disk shoe type openers. Balan at 8.4 1 ha- 1 was applied preplant for weed control. The number of emerged seedlings was counted for each plot of the 1987 and 1988 trials at the two- to four-leaf stage of growth. Plants were hand harvested after a killing frost on 2 October, 1987. Plants were placed into mesh nylon bags and air dried at ca. 32°C. Plants were then threshed, and seed yield ha- 1 was determined. Analysis of variance was calculated by using MSTAT software (Nissen 1983). Plots from the 1988 trial were not harvested because of very poor stands. Experiment 2 Trials from 1990 through 1992 were designed to test various soil-packing treatments on seedling emergence of C. fanceolata accession LN86 (obtained from Dr. S.A. Knapp, Oregon State Univ.). Plot size was 1 X 6 m with three rows 46 cm apart for the drill-planted treatments. Seeding rates on a pure live seed basis of 4.5 kg ha-1 were used. The complete field was packed once ca. 2 weeks prior to seeding. Plots were then treated with no additional packing, one additional preplant packing, or one additional postplant packing. A Brillion seeder, 3 m wide, was used for packing. Seeding was accom-plished by planter as described for experiment 1 or by broadcasting with a hand-propelled lawn seeder. Balan was also applied for weed control in these trials as described in experiment 1. A factorial, ran-domized complete block design with 4 replications was used. 24 JOUR. IOWA ACAD. SCI. 105(1998) Table 1. Experiment 1. Number of emerged seedlings of Cu-phea laminuligera accession LAll. Ames, IA 1987-1988. TREATMENT SEEDING RATE % EMERGED kg ha- 1 SEEDLINGS m- 2 SEEDLINGSa 1987 1988 1987 1988 1987 1988 1.5 1.5 12 5 16 2.1 2.5 2.5 18 7 14 1.7 3.5 3.5 26 11 16 2.0 4.5 4.5 28 10 13 1.4 lsd p=.05 8 3 Seedling depth cm 1987 1988 1.9 1.3 42 19 29 4.1 3.9 1.9 12 15 8 3.4 6.4 2.5 9 6 6 1.2 3.2 1 .1 3.8 >l >.l lsd p=.05 7 3 apercent emerged seedlings in relation to number of live seed planted The number of emerged seedlings was determined from 5 random 30-cm sections of the 3 rows in the drill-seeded plots. In the broad-cast-seeded plots, emerged seedlings in 5 random 30 cm2 sections of each plot were counted. The mean number of emerged seedlings were determined. Plots were windrowed onto large, nylon screens at harvest. Harvest was conducted the third or fourth week of Septem-ber or immediately after frost for 1990 and 1992 trials. The 1991 trial was not harvested because the stands were very poor. Plant material was air dried and subsequently threshed. Seed yields and analysis of variance were determined as in experiment 1. Experiment 3 Experiment 3 was conducted in 1993 and 1994 ro determine the effect of packing and seeding rates on varieties selected for improved emergence. The interspecific hybrid C. viscosissima X C. lanceolata accession IH50 as well as LN86 (obtained from Dr. S.A. Knapp, Oregon State Univ.) were used for these trials. IH50 had been ob-served to have good seedling emergence in selection trials at Ames in 1992. Each accession was planted at 1, 5, and 10 kg pure-live seed ha- 1 in packed and unpacked plots. Packing was accomplished just prior to seeding, but after the herbicide was applied. All other materials and methods for Experiment 3 were the same as for Ex-periment 2. RESULTS AND DISCUSSION When seedling emergence trials began in 1987, we were learning accession characteristics and were restricted by availability of seed. We had not yet determined which species of Cuphea had the best chance for successful domestication. Experiment 1 Increasing seeding depths decreased the number of emerged seed-lings and greater seeding-rates increased the number of emerged seedlings for both years (Table 1). The percentage of pure-live seed planted that emerged was low, particularly in 1988. Seed yield from 1987 plots increased with improved stands (Table 2). Trials were abandoned in 1988 after the low number of emerged seedlings was Table 2. Experiment 1. Seed yield of Cuphea laminuligera ac-cession LA 11. Ames, IA 1987. TREATMENT SEEDING RATE kg ha- 1 1.5 2.5 3.5 4.5 lsd p=.05 Seeding depth cm 1.9 3.8 6.4 lsd p=.05 SEED YIELD g m-2 3.4 5.0 6.1 6.4 1.3 6.8 5.5 3.3 1.1 Table 3. Experiment 2. Seedling emergence Cuphea lanceolata accession LA86. Ames, IA. EMERGED % EMERGED SEEDLINGS m- 2 SEEDLINGSa TREATMENT 1990 1991 1992 1990 1991 1992 Drilled 66 30 84 41 18 51 Broadcast 78 21 67 46 12 41 lsd p=.05 NS NS 5 Packing +Oppb 87 25 81 54 15 49 +l~pb 61 29 77 37 17 48 lpp +l 64 22 64 39 13 42 postc lsd p=.05 NS NS NS a Percent emerged seedlings in relation to number of live seed planted bpp = preplant packing cpost = postplant packing determined. The reason for very poor seedling emergence in 1988 was not determined. Experiment 2 Data from experiment 1 indicated the necessity for shallow plant-ing depths. Heavy rains immediately after planting in 1989 con-tributed"l:o poor emergence. Replanting after the rain had compacted the soil resulted in adequate seedling emergence. This observation along with increased seedling emergence in tractor wheel tracks led to the decision to test packing on seedling emergence in 1990. The complete field was packed ca. 2 weeks before planting to simulate compaction observed following heavy rain the previous year. Also, we wanted to test very shallow seeding made possible by broadcast seeding. There were no significant differences in the number of emerged seedlings from drilled or broadcast plots in 1990 and 1991 (Table 3). Statistically, more emerged seedlings were counted in drilled plots than in broadcast plots in 1992. In 1990 trials, slightly greater numbers and percentages of seedlings emerged in broadcast plots, but in the other two years (1991 and 1992) the drilled plots had slightly higher numbers and percent emerged seedlings. Additional MANAGING CUPHEA SEEDLINGS 25 Table 4. Experiment 2. Seed yield Cuphea lanceolata accession LA86. Ames, IA. SEED YIELD g m-2 TREATMENT 1990 1992 Drilled 10.4 29.3 Broadcast 12.8 31.0 lsd p=.05 NS NS +Oppa 10.3 30.8 +lppa 13.1 29.2 + lppa+ lpostb 11.4 30.6 lsd p=.05 NS NS apreplant packing bpostplant packing Table 5. Experiment 3. Seedling emergence of Cuphea lanceo-lata accessions LN86 and IH50. Ames, IA. SEEDLINGS m-2 % EMERGENCE TREATMENT 1993 1994 1993 1994 LN86 18 45 9.7 31.4 IH50 21 44 11.1 30.3 packedb 16 55* 8.9 38.3 unpackedb 22 35* 12.1 23.9 Seeding rate kg ha - 1 1 5 11 2.9 12.6 5 21 38 11.5 26.4 10 31 85 16.9 29.4 lsd p = .05 10 18 *Means significantly different at p= .05 Percent emerged seedlings in relation to number of live seed planted bMeans of LN86 and IH50 together soil packing had no significant effect on numbers of emerged seed-lings. Heavy rains immediately after planting in 1991 caused severe soil erosion and loss of stand. Planting method or additional soil packing did not significantly affect seed yields from harvested plots in 1990 or 1992 (Table 4). Experiment 3 Knapp (1993) proposed developing the interspecific hybrid C. vis-cosissima X C. lanceolata for commercial production of Cuphea. We had observed IH50 (a selection of this hybrid developed by Knapp) in selection trials in 1992. This accession had significantly better seedling emergence than other hybrid selections grown (Roath un-publ. data 1992). We included this accession, along with LN86, in 1993 and 1994 trials. LN86 and IH50 had nearly equal numbers and percentage of emerged seedlings in 1993 and 1994 trials (Table 5). Soil packing provided mixed results in these trials (Table 5). In 1993, there was no significant differences between the number of emerged seedlings in packed and unpacked plots. However, un-packed plots had greater actual numbers and percent of emerged seedlings than did plots with soil packing. Here again, heavy rains immediately after planting caused severe washing and stand loss. The Table 6. Experiment 3. Seed yield of Cuphea lanceolata acces-sion LN86 and IH50. Ames, IA. SEED YIELD g m-2 TREATMENT 1993 1994 LN86 20 66 IH50 22 75 packed 25* 74 unpacked 17* 67 Seed rate kg ha -1 1 17 51 5 23 81 10 23 80 lsd p=.05 NS 14 *Means significantly different at p= .05 number of emerging seedlings could have been affected more by rain-caused soil erosion than by packing or the lack of it. There were significantly more seedlings that emerged in packed than in un-packed plots in 1994. Increasing seeding rates increased the number and percent of emerged seedling in these trials (Table 5). There were no significant differences in yield of the two cultivars grown in the 1993 and 1994 trials (Table 6). Packed plots had greater yield than unpacked plots in 1993, whereas the number of emerged seedlings was greater in unpacked plots (Table 5). In 1994, increasing seed rates to 5 kg ha- 1 resulted in increased yields, but additional increases in seeding rates had no effect on seed yield. Both of these accessions have the wild type mature-seed presentation (Gra-ham 1988), and are, therefore, susceptible to seed shatter. It is pos-sible that a high percentage of seed had shattered and was not re-covered during harvest. This could at least partially explain the in-consistent relationships between stand and seed yield, as well as the relatively low yields. These two accession have vigorous growth hab-its and are able to grow and flower continuously throughout the season. This character could explain some of the plants' ability to compensate for insufficient stand by producing larger plants to oc-cupy spaces between plants. Consistent stand establishment continues to be a barrier to grow-ing Cuphea successfully at Ames, Iowa. Small seed size and light required for germination dictates shallow planting, which exacer-bates the problem. Variations in seedbed conditions inherent to rain-fed conditions contributes to the problem. Although data were not conclusive, it appeared that soil packing can help increase the num-ber of emerged seedlings. The only variable that consistently in-creased the number of emerged seedlings was an increased number of planted seed. We were not successful in obtaining seedling emer-gence of more than 54% of pure-live seed planted at the highest seeding rates, and more often only 30% to 40% of pure-live seed emerged. Untimely rainfall contributed to emergence problems. Heavy rain prior to seedling emergence can cause severe washing and loss of stand. This is a difficult problem to overcome, as rain amounts are often unpredictable, and shallow planting into packed seedbeds are particularly susceptible to erosion. Additional research on seedling emergence under a wider range of environmental conditions would be necessary prior to commercial planting of Cuphea in Iowa. 26 JOUR. IOWA ACAD. SCI. 105(1998) LITERATURE CITED GRAHAM, S. A. 1988. Revision of Cuphea section Heterodon (Lythraceae). Systematic Botany Monographs. American Society Plant Taxonomists, Ann Arbor, MI. GRAHAM, S. A. 1989. Cuphea: A new plant source of medium-chain fatty acids. Critical Review of Food Science and Nutrition 28:139-173. KNAPP, S. J. 1993. Breakthroughs toward domestication of Cuphea. p. 372-379. In). Janick and J.E. Simon, eds. New Crops. J. Wiley and Sons, New York. NISSEN, 0. 1983. MSTAT, a microcomputer program for the design, man-agement, and analysis of agronomic research experiments. Michigan State Univ., E. Lansing, MI. THOMPSON, A. E. 1984. Cuphea: a potential new crop. HortScience 19(3): 353-354. 

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Managing Seedling Emergence of Cuphea in Iowa

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