Rates of organic and conventional slow release and soluble fertilizers were evaluated for lisianthus, which was found to have moderate fertility requirement: 1.8 to 3.6 kg per cubic meter conventional slow release fertilizer (Nutricote 20-3-8.3) and soluble fertilizers of organic Daniel’s (10-1.7-2.5) and conventional salt-formulated fertilizer at 75 to 150 ppm nitrogen produced optimal yield.
Light, air temperature, fertilization, and humidity were evaluated to optimize germination of the cut flower ‘Temptress’ poppy, which promises lucrative economic returns for market farmers. Optimal growth was obtained with cool air temperatures of 18 C, elevated humidity, and light fertilization with 25 ppm nitrogen.
Organic cropping practices are not limited to farms producing foodstuffs. Many ornamental crop and specialty cut flower producers also seek to adopt sustainable production practices. However, little information is available concerning the use of organically-certifiable fertilizers for cut flower production. Lisianthus (Eustoma grandiflorum) is a very popular cut flower for production by market farmers and represents a model species to study organic versus conventional fertilization practices for cut flower cropping systems.
Since its release, giant Oriental poppy (Papaver orientale ‘Temptress’) has rapidly gained popularity among specialty cut flower producers due to its large flowers, which can reach 9 cm in diameter. Very few guidelines that cite optimal environmental conditions for germination and seedling development of Oriental poppy are available, and what is published is in conflict. Cut flower growers have expressed frustration with germination of the expensive seed for this crop.
The original goal of this research project was to generate practical information about the use of organic compared to inorganic fertilization for cut flowers produced in Haygrove high tunnels. During June and July 2004, an experiment was conducted in the Haygrove tunnels at the Eastern Kansas Horticulture Research and Extension Center in Olathe, Kansas, to compare organic versus conventional fertilizers at three rates of application for sunflower production in Haygrove tunnels. However, the soil was already so fertile that no treatment differences were observed in this preliminary experiment (see 2005 Annual Report).
Unfortunately, all high tunnels at the Eastern Kansas Horticulture Research and Extension Center were destroyed by a microburst in August 2004 (see http://www.hightunnels.org/ForGrowers/GrowersUsing/OlatheStormDamage.htm for photos of damage.) Four experiments associated with this project were planted in the Haygrove high tunnels at the time of the microburst and were destroyed (organic versus conventional fertilization studies for cut sunflower, lisianthus, ornamental kale, and ‘Temptress’ poppy). Reconstruction of the high tunnels occurred over the next 1.5 years, which made their use in the project of this report unfeasible, though we now have a working knowledge of the management issues associated with Haygrove high tunnels to pass along to farmers.
The research site was moved to the greenhouses of Kansas State University’s main campus in Manhattan, Kansas, where organic versus conventional fertilization of the cut flower lisianthus was studied. In addition, the objective of determining optimal environmental conditions for germination and seedling development of ‘Temptress’ poppy was added to the project. The final objective of the project is to share the information generated with cut flower growers and market farmers via www.hightunnels.org and the Association of Specialty Cut Flower Growers’ (ASCFG) Cut Flower Quarterly.
Organic versus Conventional Fertilization of Lisianthus
An experiment was conducted in a glass greenhouse at Kansas State University in (Manhattan, Kans.) to determine the response of Eustoma grandiflorum (Raf.) Shinn. ‘Balboa Rose’ (currently named ‘ABC 2-3 Rose’) to four different nutrient sources: an organic and a conventional (inorganic) slow-release fertilizer and an organic and a conventional soluble fertilizer. A control treatment received no fertilizer.
The slow release fertilizers that were chosen for this study are commercially available fertilizers. The slow-release, conventional fertilizer was nine month release 20-7-10 Nutricote (Plant Products Co. Ltd., Brampton, Ontario), a resin-covered nitrate formula which allowed for slow release lasting up to nine months. This slow release fertilizer consists of 20% N from potassium nitrate and ammonium nitrate. Nutricote treatments were at rates of: 1.8 kg.1 m-3 (3 lb.yd-3; low); 3.6 kg.1 m-3 (6 lb.yd-3; moderate) and 7.1 kg.1 m-3 (12 lb.yd-3: high). The slow-release organic fertilizer was 10-2-6 Lawn Restore (Woodstream Corp., Lititz, Penn.) pelletted fertilizer. Indications are that it provides nutrients for up to eight weeks in lawn applications (lower temperatures than found in greenhouse situations). Lawn Restore consists of hydrolyzed poultry feather meal, nitrate of soda, potassium sulfate, bone meal and soybean meal. The analysis as provided by Woodstream Corp. is: 10:2:6 N2: P2O5: K2O with1.9% NO3- N as Chilean nitrate (nitrate of soda), 0.5% other water soluble nitrogen, and 7.6% water insoluble nitrogen. Lawn Restore treatments were: 3.6 kg.1 m-3 (6 lb.yd-3; low); 7.1 kg.1 m-3 (12 lb.yd-3; moderate) and 14.3 kg. 1 m-3 (24 lb.yd-3; high). Rates of N were similar between the conventional and organic slow-release fertilizer treatments. The soluble conventional inorganic fertilizer was formulated from the salts KNO3, NH4H2PO4, NH4NO3 and Ca(NO3)2 to mirror the ratio of N:P:K in the commercial organic source. The organic soluble fertilizer was the commercially available Daniel’s 10-4-3 (Daniel’s Fertilizer Co., Sherman, Texas.) at rates of 75 ppm N (low), 150 ppm N (moderate) and 300 ppm N (high). Daniel’s soluble fertilizer is a by-product of oilseed (such as soybean) extracts.
Pro-Mix ‘BX’ (Premier Horticulture, Rivière-du-Loup, Québec) which consisted of 75 to 85% peat with 15 to 25% perlite and vermiculite was further amended to suit the porosity and pH requirements of lisianthus. Horticultural grade perlite (Lite Weight Products, Inc., Kansas City, Kans.) was added at a rate of 5% media volume. Pre-plant nutrient amendments of 0.6 g MgSO4 .L-1; 0.6 g potash of sulfate.L-1, 1.8 g dolomitic lime (Deco Lawnlime, Georgia Marble Co., Kennesaw, Ga.) .L-1 were also incorporated. The starting pH of the amended media (without slow release fertilizer treatments) was 6.7 and the electrical conductivity (EC) was 0.89 mmho.cm-1. The starting pH and EC were determined by watering fallow pots three times over one week and collecting a pour-thru leachate sample (Whipker, et al., 2000). Nine dry liters of this medium was measured out for each pot. Slow-release fertilizer treatment materials were incorporated at the stated rates.
Treatment structure was factorial with four fertilizers by three rates of each fertilizer plus a no-fertilizer control. Experimental design was randomized complete block with four replications and three plants per experimental unit (pot). Lisianthus plugs were produced by Speedling, Inc. (San Juan Bautista, Calif.) and arrived at Kansas State University on 06 Jan. 2005. On 08 Jan. 2005, the 410 plugs (volume: 4.43 cm3, dimensions: 11.5 mm x 11.5 mm x 30 mm) were transplanted into 84 plug trays (volume: 20.57 cm3, dimensions [six sided plugs]: 32mm x 29mm x 40.5mm) using Pro Mix PGX plug and germination growing media (Premier Horticulture, Rivière-du-Loup, Québec) and were fertilized with 20-10-20 Peter’s soluble fertilizer (Scotts, Marysville, Ohio) at a rate of 30 ppm N. On 22 Jan. 2005 (experiment day 0), plugs were transplanted into 28 cm (11 inch) diameter (approximately 9 L volume) nursery pots using the previously described media.
After transplanting, the control and slow-release fertilizer treatments received tap water at every irrigation and the soluble fertilizer treatments received their respective fertilizer solution. Just over one liter (1,030 ml) of solution was applied at each irrigation. When weight of pots dropped 25% to 28% due to water loss, pots were watered or fertigated. Leaching fraction was approximately 35 to 45%.
On experiment days 11, 23, 37, 54 and 67, pots were watered or fertigated to bring them to container capacity by applying 1,580 ml solution, this was followed by a one hour equilibration period. Then a plastic saucer (29.5 cm inner diameter) was placed under each pot and 200 ml of tap water was poured onto the root medium surface. The pH of the leachate was measured using the EXTECH Oyster pH Meter (EXTECH Instr., Waltham, Mass.) and EC was measured using the EXTECH Conductivity Meter (Model 695, EXTECH Instr., Waltham, Mass.). After experiment day 67, 2,060 ml solution was used to bring the pots to container capacity. This revised Pour-Thru leaching procedure was performed on experiment day 81. The rest of the leaching procedure was performed as previously detailed.
Air temperature was monitored every 30 minutes, 24 hours a day, using a Hobo sensor (Onset Computer Corp., Bourne, Mass.). The average air temperature measured from experiment day one to experiment day 83 ranged from 9oC to 43oC (49oF to 109oF) and averaged 19oC (66oF).
Plant growth data collected during the production cycle included a rating of plant development assigned to each plant in each experimental unit on experiment days 37, 54, 67, and 81. The rating scale was zero (a dead plant) to ten (optimal growth). Ratings were based on plant height, general leaf size, approximate leaf number and color of plant. The appearance of the plant also affected the rating it received. Clorosis, tip burn, flagging, and short internodes negatively affected a plant’s rating while fully expanded, healthy foliage, thick, healthy stems, good height and color all resulted in higher ratings.
Non-terminal growth data was collected on experiment day 82. Measurements were collected from two plants per experimental unit and averaged. Plant height (from the soil surface to the top of the foliage canopy), stem caliper (from the internode below the third leaf pair below the terminal bud), leaf length and width (third leaf pair below the terminal bud), number of leaf pairs, and SPAD reading (Minolta SPAD 502 Chlorophyll Meter; Spectrum Technologies, Plainfield, Ill). The SPAD reading is an estimation of the amount of chlorophyll in a leaf.
Germination and Seedling Development of Giant Oriental Poppy
After a preliminary experiment to establish base germination rates of each cultivar and seed lot used, three experiments were conducted in Conviron growth chambers (Winnipeg, Manitoba) at Kansas State University in Manhattan, KS, to determine environmental conditions necessary for optimal germination and seedling development of ornamental poppy (Papaver orientale L.) ‘Temptress Orange’ and ‘Temptress White’. Plug trays with 200 cells (each cell measured 2.2 cm x 2.2 cm and had a volume of 10.5 cm3) were filled with Fafard super-fine germination media (for experiments one and two; Agawam, Mass) or Premier Pro Mix PGX professional plug and germination growing media (used in experiment three; Premier Horticulture, Rivière-du-Loup, Québec). Poppy seeds were manually sown using a Pro-seeder (Hamilton Design Ltd., Berks, United Kingdom). Replications were conducted in five different growth chambers. Each day, every seed was inspected; germination was defined as early radicle emergence (Stage 1; Styler and Koranski, 1997). Air temperature and relative humidity were recorded every half hour using Hobo sensors (Onset Computer Corp., Bourne, Mass.). Data were subjected to analysis of variance using PROC GLIMMIX in SAS version 9.1.3 (SAS Institute, Cary, N.C.)
Petri plate seed germination. Initial germination percentages (seed viability) of both cultivars and each seed lot of ‘Temptress’ poppy, were determined in a small scale Petri plate experiment. Covered Pyrex Petri plates (plate: 8.6 cm inner-diameter, 1.8 cm height, 95 cm3 volume; cover: 9.5 cm inner-diameter, 1.5 cm height; Corning Inc., Reston, Virginia) were fitted with one piece of filter paper (P8 [coarse], Fischer Scientific, Hampton, N.H.) and wetted with de-ionized water. Twenty-five representative seeds from each separate seed lot used in the growth chamber studies (one lot of ‘Temptress White’ and two lots of ‘Temptress Orange’) were placed on each plate (experimental unit). Seeds were maintained by adding de-ionized water daily. Plates were placed in a growth chamber set at 24oC and 16 h day length. After eight days, the number of seeds that germinated was recorded. Experimental design was completely random (CRD) with three replications per seed lot.
Germination studies (Experiments 1 and 2).
Media used in experiments one and two was Fafard super-fine germination media which had a starting pH of 5.49 and an EC of 1.39. Germination of two cultivars was evaluated: ‘Temptress White’ and ‘Temptress Orange’ (lot 1). The date of germination for each seed was tracked, and percent germination and average number of days after sowing that seed germinated (DAS) was calculated for each experimental unit which consisted of 20 seeds of one cultivar. Relative humidity was kept elevated in the growth chambers by filling three shallow ”half-flats” (3,500 cm3 volume) with tap water and misting with de-ionized water daily. Felt capillary mats were kept wet with de-ionized water in the bottom of other “half-flats” and plug cells with poppy seeds were placed in them after poppy seeds were sown. Each day when germination was tracked, the de-ionized water was replenished and seeds and media were misted. Each run lasted 13 days.
Experimental designs were randomized complete block (RCB) with treatment structures of light (Expt. 1) or temperature (Expt. 2) as main plots and cultivar as sub-plots. Each treatment was replicated three times in randomly assigned growth chambers, and two experimental units of each cultivar were included in each run.
Light or dark germination study (Experiment 1).
Poppy germination was evaluated under conditions of 16 h light (range 40 µmol.m-2.s-1 to 82 µmol.m-2.s-1, average 50 µmol.m-2.s-1) versus 24 h dark. Seed germination was counted daily in the dark treatment by using a green light, which limited the amount of photosynthetically-active radiation to which the seeds were exposed (Wesson and Wareing, 1969). Air temperature set-point in all chambers was 24oC (75oF) for 24 hours. Actual temperature ranged from 19oC to 29oC (67oF to 84oF) and averaged 25oC (77oF). The vapor pressure deficit (VPD) for the light treatments averaged 1.1 kPa with a maximum of 3.27 kPa and a minimum of 0.34 kPa (relative humidity ranged from 24% to 87% and averaged 67%). In the growth chambers with 24 h of dark, average VPD was 1.17 kPa while the maximum was 2.54 kPa and the minimum was 0.45 kPa (relative humidity ranged from 24% to 85% and averaged 64%).
Air temperature germination study (Experiment 2).
Poppy germination was evaluated at three air temperature set points: 18oC (low), 24oC (moderate), and 32oC (high; 65oF, 75oF and 90oF respectively). Air temperature set-points remained constant over 24 h. Actual air temperatures for the low treatment ranged from 18oC to 22oC with an average of 19oC (64oF to 71oF, average 65oF). The low air temperature treatment had an average VPD of 0.5 kPa, a maximum of 1.13 kPa and a minimum of 0.02 kPa (relative humidity ranged from 49% to 99% and averaged 77%). Actual temperatures for the moderate air temperature treatment ranged from 21oC to 29oC (67oF to 84oF) and averaged 24oC (77oF). The VPD for the moderate air temperature treatment averaged 1.1 kPa with the maximum of 3.27 kPa and a minimum of 0.34 kPa (relative humidity ranged from 24% to 87% and averaged 67%). Actual temperatures for the high air temperature treatment ranged from 30oC to 34oC (83oF to 94oF) and averaged 32oC (90oF). The VPD for the high air temperature treatment averaged 2.0 kPa with a maximum of 3.9 kPa and a minimum of 0.72 kPa (relative humidity ranged from 24% to 84% and averaged 59%). Seeds were subjected to 16 h light periods (range 40 µmol.m-2.s-1 to 82 µmol.m-2.s-1, average: 50 µmol.m-2.s-1).
Seedling Development (Experiment 3).
The third experiment was extended beyond germination to allow seedling development under treatment conditions; each run lasted 21 days. Germination and development of two cultivars was evaluated: ‘Temptress White’ and ‘Temptress Orange’ (lot 2). Treatments were three air temperature set-points of 16oC (low), 24oC (moderate) and 33oC (high; 65oF, 75oF and 90oF respectively); two relative humidity environments (ambient and high) and two fertilization regimes (with and without). Experimental design was randomized complete block (RCB) and treatment structure was a split plot with air temperature as the main plots, humidity by fertility as the sub-plots and cultivar as the sub-sub-plots. Air temperature set-points remained constant over 24 h.
The high humidity treatment was accomplished by covering half of the experimental units in each growth chamber with a transparent plastic dome (55.1cm x 28.8cm x 14.2cm, Acrodome #69973, AcroPlastic Ltd., Edmonton, Can.) that had six 1.5cm x 4 cm holes cut in them to avoid excessive heat build up. De-ionized water was used to mist under the domes daily. Treatments with fertilizer received 25 ppm N from 20-10-20 soluble Peter’s Peat-lite Special (Scotts, Marysville, Ohio) as a spray of approximately 25 mL per experimental unit every other day starting at experiment day ten. Each experimental unit consisted of 25 seeds of one cultivar, sown one seed per cell in media-filled plug trays as previously described. Media used in experiment three was Premier Pro Mix PGX professional plug and germination growing media which had a starting pH of 6.26 and EC 1.25.
Treatments without fertilizer were repeated four times and treatments with fertilizer were repeated three times in randomly assigned growth chambers. Day length was 16 h; and light levels averaged 162 µmol.m-2.s-1 and ranged from 82 µmol.m-2.s-1 to 216 µmol.m-2.s-1).
In addition to tracking the date of germination for each seed and average number of days after sowing that seed germinated (DAS), stage of seedling development was assessed at harvest (experiment day 21). The development of seedlings was based on a seven point rating scale that considered seedling color, vigor of shoot, cotyledon expansion, and true leaf expansion, with zero representing death and seven representing a seedling with cotyledons and six true leaves expanded.
Organic versus Conventional Fertilization of Lisianthus
Based on nearly all growth parameters measured on experiment day 81, all conventional slow release rates, the low organic slow release fertilizer and the low and moderate rates of both soluble fertilizers resulted in similar growth. The only exception is that the low rate of organic slow release fertilizer did not perform as well as the others listed above based on leaf length.
The optimum media EC for lisianthus production has been reported as 1.0 to 1.2 mmhos.cm-1 (Gill et al., 2000; PanAmerican Seed, 2005). Of the treatments with the best growth, all of the conventional slow release treatments and the organic low treatment stayed within 2 and 2.75 mmhos.cm-1, until after day 54 when the EC for the conventional high slow release treatment went over 3 mmhos.cm-1. The two slow release rates that failed to produce acceptable growth were the moderate and high levels of the organic fertilizer. These treatments were both above 2.5 mmhos.cm-1 by experiment day 23 and raised to an unacceptable 5.62 and 8.28 (moderate and high rates respectively) by experiment day 67. These high salt levels no doubt contributed to poor plant growth. Among these treatments, those plants that survived the toxic salt levels had poor root development and had very clorotic leaves (SPAD readings of 5.38 for the high organic slow release treatment.
Based on published recommended EC rates and growth data gathered in this experiment, a conventional slow release fertilizer like 20-7-10 Nutricote rates of 1.8 kg.1 m-3 to 3.6 kg.1 m-3 (low and moderate rates in this experiment) could be recommended. Because there is no significant difference in growth parameters between any of the rates of Nutricote, there is no benefit to using a rate higher than 3.6 kg.1 m-3. The slow-release organic fertilizer,10-2-6 Lawn Restore, at the low rate 3.6 kg.1 m-3, although not significantly different, showed slightly poorer growth than the conventional slow release treatments at all rates.
The low and moderate rates (75 and 150 ppm N respectively) of both conventional and organic soluble fertilizers had the best growth responses of soluble treatments. The conventional and organic low treatments (75 ppm N) stayed below 1.6 mmhos.cm-1 for the duration of the experiment. The moderate soluble treatments reached 2.5 mmhos.cm-1 at their highest, while the conventional soluble high treatment had a maximum of 4.4 mmhos.cm-1 and the high organic reached 3.96 mmhos.cm-1. These high salt levels make soluble constant liquid feed rates over 150 ppm N ill-advised. Data from this experiment suggests that rates of 75 to 100 ppm N from either conventional or organic constant liquid feed are appropriate for this crop.
Because lisianthus is a pH sensitive crop, with an approximate pH requirement of between 6.3 and 6.7, it is necessary to address the impact that N form may have on media pH (Harbaugh and Woltz, 1991). Conventional and organic fertilizers traditionally have different forms of N. The conventional slow release fertilizer had a concentration of 9.3:10.7 NH4-N to NO3-N while the organic slow release had a NH4-N:NO3-N ratio of 4:1. The conventional soluble fertilizer had a NH4-N to NO3-N ratio of 1:3 while the organic soluble feed was 4:1 NH4-N:NO3-N. The conventional organic fertilizers fell below optimal pH levels until experiment day 39, but the pH gradually increased, bringing the low and moderate conventional slow release treatments to 6.6 and 6.7 by the end of the experiment. The high conventional slow release treatment had consistently low pH values. Because the conventional fertilizers had a lower concentration of NH4-N than the organic fertilizers, it is reasonable to presume that the pH of the organic treatments would be lower than those of the conventional treatments. pH would be lowered when there is a greater amount of NH4-N being absorbed by plants. When more NH4-N is taken up by plants, the plant releases H+ ions which lowers pH. This is not the trend that was observed in this experiment, however. The NO3-N from the organic slow release fertilizer was available much faster than was anticipated. Because of the high amounts of NO3-N in the organic slow release fertilizer, the pH rose dramatically, reaching a pH of 7.7 in the organic high slow release treatment by experiment day 39 and then plummeting to 5.19 by the end of the experiment. The pH of the organic soluble feed treatments followed anticipated trends more closely. Because the NH4-N of the organic soluble feed was much more available to the plants for uptake, the pH of the media was lower than the organic slow release pH values.
Although the uptake of NH4-N can greatly lower the pH of media, it is important to recognize that the pH fluctuations may not be entirely due to N absorption by plants; microbial activity undoubtedly impacted the media pH, as well.
Final growth data that was collected corresponds with EC and pH data. The treatments that showed the greatest deviation from suggested EC and pH rates also had the poorest growth. By experiment day 39, the conventional slow release treatments had significantly better growth than both the moderate and high rates of organic slow release fertilizer, a trend that continues throughout the duration of the experiment. These two treatments also had the highest EC and the highest pH before this day. From experiment day 39 continuing to the end of the experiment, the organic moderate and high slow release treatments performed worse than the no fertilizer control. In the soluble treatments, the conventional moderate treatment was quickly established as having highest growth stages. At experiment day 39, the conventional and organic high rates of soluble feed were at significantly lower stages than the conventional moderate treatment. This continued throughout the experiment with the high soluble treatments eventually being at significantly lower stages than all other soluble treatments except for the control. Although not significantly different at α=0.05, the no fertilizer control had higher mean stage rating than both soluble high treatments beginning at experiment day 39.
Based on this experiment, it is possible to use either conventional or organic fertilization methods in the production of cut-flower lisianthus. The conventional slow release fertilizer used (Nutricote 20-7-10) was effective at all tested rates, so the low and moderate fertilization rates (1.8 kg.1 m-3 to 3.6 kg.1 m-3) tested here are recommended. The organic slow release fertilizer that was used proved to be an inappropriate choice for this crop at rates over 3.6 kg.1 m-3 because of the high rate of NO3-N that was released and negatively affected EC and pH early in the cropping cycle. The Lawn Restore organic slow release fertilizer has the potential to be an adequate choice for fertilizer in field settings due to the cool soil temperatures that would slow the release of NO3-N; this should be studied further. Lisianthus has moderate fertility requirements, therefore a constant liquid feed of 75 to 150 ppm N from either a conventional or organic source will provide adequate nutrition. This research offers recommendations to lisianthus producers who are looking for feeding options beyond the suggested 1200 ppm N once per week (Frett et. al., 1988). The options of constant liquid feed or a slow release fertilizer are very compatible with the automated production used by many of today’s market farmers.
Germination and Seedling Development of Giant Oriental Poppy
Petri plate seed germination. Germination is defined as “the emergence and development from the seed embryo of those essential structures which. . .are indicative of the ability to produce a normal plant under favorable conditions”. Radicle emergence in the Petri plate study occurred under such favorable conditions as defined by AOSA in Rules for Testing Seeds and therefore the results from this preliminary test suggest the maximum germination expected from each cultivar and seed lot in growth chamber experiments. In the growth chamber experiments, “favorable conditions” are not necessarily provided based on treatment regimes and because seed are sown in a commercial root medium that may have affected the ability of the seedling to penetrate. The average germination for the single lot of ‘Temptress White’ was 44%. ‘Temptress Orange’ average germination percentage was 60% for lot one and 82% for lot two.
Light or dark germination study (Experiment 1).
Germination of the white cultivar was 38% less than that of the orange cultivar which had 81% germination after 13 days (p<0.0001). Interestingly, the germination of the white cultivar was similar to the results of the Petri plate study while the germination of the orange cultivar was about 20% less in the Petri plate study. White poppies germinated about 0.8 d later than orange poppies (p=0.0129). Differences in percent germination between cultivars began five days after sowing (DAS) in the 16 h light treatment (p=0.0009) and in the 24 h dark treatment (p=0.0052) and were apparent throughout the rest of the experiment.
Germinating seeds under 16 h of light compared to 24 h of darkness resulted in about 8% more germination, but this difference is only significant at α=0.1 (p=0.0931). This suggests that the current recommendations for leaving Papaver orientale seed exposed to light during germination (Dole and Wilkins, 1999; Fred C. Gloeckner, 2005; Nau, 1993, Ohio Florists Assoc., 1999; Perry, 1998) is not essential; in fact, germination of the white cultivar was similar under both light and dark conditions.
Literature reviews in research reports of other ornamental plants have also suggested that recommendations for environmental conditions during germination are variable across published sources (e.g. Shoemaker and Carlson, 1992). An experiment testing the germination conditions for fibrous-rooted begonia determined that light was required for germination, but at a shorter period than was reported in published works (Shoemaker and Carlson, 1992). The effect of light on another member of the Papaver genus, Papaver dubium (long-headed poppy), indicated that germination was “unaffected or slightly inhibited by light” (Wesson and Wareing, 1969). Chen (1968) found that the light by temperature interaction had a great impact on overcoming light-inhibited dormancy of Nemophila insignis; this interaction should also be investigated with the ‘Temptress’ cultivar. The fact that poppies do not require light for the first few days after imbibition can be of benefit to growers in that a variety of light environments will result in optimal germination, from dark germination chambers to ambient light conditions on a greenhouse bench. Because light is not a critical consideration during the first stage of germination, growers can inexpensively and easily maintain a high humidity environment by covering the germinating seeds with either a plastic bag or tray (Stamback, pers. communication).
Air temperature germination study (Experiment 2).
Germination percentage of the white cultivar was about 38% less than that for the orange cultivar (p<0.0001) which was consistent with results from Experiment 1. The germination of the white cultivar was similar in the air temperature experiment as it was in the Petri plate study, but was again about 20% greater in the air temperature experiment for the orange cultivar. Beginning at three days after sowing, germination was different between the white and orange cultivars at 24oC (p=0.0159) with the germination percentage of the white cultivar at 9% and the germination percentage of the orange cultivar at 18%. The results of this experiment refute the idea that heat accumulation plays a role in germination of Oriental poppies because seeds at 18oC germinate just as quickly as seeds at 24oC and 32oC. Cultivar differences were the only significant factor in this study until eleven days after sowing when germination was different between 24oC and 32oC air temperature for ‘Temptress Orange’ (p=0.0413). At day eleven, mean germination of ‘Temptress Orange’ at 24oC was 87% while germination of the same cultivar at 32oC was only 78%. While air temperatures as high as 32oC (90oF) did have a marginally negative affect on poppy germination (p=0.0947), temperatures between 18oC and 24oC (65oF and 75oF) resulted in maximum germination percentages. This result is consistent with most of the literature (Dole and Wilkins, 1999; Nau, 1993, Ohio Florists Assoc., 1999). However, in a preliminary study conducted in the Kansas State University greenhouses, germination of ‘Temptress Mix’ poppy seeds occurred after air temperatures had reached 43oC (110oF; data not shown). Seedling development (Experiment 3). The germination percentages that were achieved in the seedling development study mirrored the light and dark experiment, and the air temperature experiment as well as the Petri plate study. The white cultivar germinated at a rate of 50% and the orange cultivar at a rate of 77%. Because the differences between cultivars were so great that they masked the treatment affects of the environmental parameters, additional statistics were completed ‘by cultivar’. At final harvest, the percent of live seedlings was calculated. The average stage was also assessed at this time. Though there were no significant differences in the average stage at final harvest between the air temperature treatments, there were significant differences in the percent of plugs alive at final harvest between air temperatures. Low and moderate air temperatures proved to support a higher percent of seedlings alive at day 21 in both cultivars. The percent alive at final harvest had similar values to the germination percentages that were found in all experiments and the Petri plate study. Surprisingly, the average stage at final harvest showed no statistically significant differences between any of the temperature treatments, however considerable visible differences can be noted between low air temperature and high air temperature treatments. Upon completing the 21 d cycle in their respective chambers, plugs from 16oC and 33oC treatments were placed in moderate temperatures (24oC) for seven to ten days. The plugs were moved to equilibrate the development environment to assess if the negative high air temperature effects could be reversed. This observation showed that the plugs that had been moved from a low air temperature to a moderate air temperature looked to be much larger and healthier than those that were moved from high air temperatures to moderate air temperatures leading to the conclusion that damage from heat stress within the first weeks of development is not easily overcome. Because this observation was only based on one replication from the low air temperature treatment and two replications from the high air temperature treatment, no statistics are shown. The many different treatments in this experiment allowed interactions between air temperature, humidity and fertility to be assessed. Within the low air temperature treatment, the high humidity environment allowed for significantly more seedlings of the white cultivar to be alive at final harvest than in the ambient treatment (p=0.0167) while the humidity and air temperature interactions had no significant affect on the percent of seedlings alive at harvest in moderate or high air temperatures in the white cultivar or in any air temperatures in the orange cultivar. The stage of seedlings at final harvest was significantly higher in the high humidity treatment over the ambient treatment in both the moderate and the high air temperature treatments for cultivars. This leads to the conclusion that lower air temperatures (16oC to 24oC) and/or humid environments would encourage successful seedling development. Cooler air temperatures and smaller VPD allow for less water loss due to transpiration, therefore keeping seedlings turgid in this delicate stage. Fertilization began ten days after sowing seed, therefore one would expect that the fertilization treatment would only affect the percent of seedlings alive at final harvest and the stage of the seedlings at final harvest. The low air temperature treatments showed differences between fertilized plugs and non-fertilized plugs in percent alive at harvest in both cultivars (‘Temptress White’ p=0.0196, ‘Temptress Orange’ p=0.0304) and in stage at harvest in the orange cultivar (p=0.0018). Oddly enough, the fertilizer had a negative affect on the white seedlings at low air temperatures, while the orange cultivar responded favorably to fertilizer in regards to both percent alive at harvest and stage at harvest. At high air temperatures, only the orange cultivar showed a significant reaction to fertilizer, with stage at harvest being increased in seedlings that were fertilized. ‘Temptress White’ and ‘Temptress Orange’ seedlings that were fertilized showed a significantly higher number of seedlings alive at harvest at low and moderate air temperatures than at high air temperatures. In the white unfertilized seedlings, the percentage of seedlings alive at harvest was greater in the moderate temperature than in both the low or high air temperatures. The moderate air temperature allowed for greater stages at final harvest over the high air temperature in both cultivars and over the low temperature in the orange cultivar. The germination differences that were consistently observed between ‘Temptress White’ and ‘Temptress Orange’ poppies could be due to a lack of or less carotenoid synthesis in the white mutant cultivar; however, all photosynthetically-active life must contain carotenoids (Park et al., 2002). Carotenoids are present in large amounts in orange (wild-type) Eschscholzia californica (California poppy) where the orange trait is dominant over the mutant white traits. When white petals of California poppy occur, they are found simultaneously with white pollen and in most species, flowers with white pollen are sterile (Wakelin et al, 2003). Unusually, the white pollen of California poppies is fertile, but contains no carotenoids, although the authors state that California poppies do not require carotenoids for pollen fertility (Wakelin et al., 2003). These findings could be related to the consistently poorer germination of the white cultivar in our research. Based on these experiments, germination conditions that can be recommended to growers for Papaver orientale ‘Temptress’ are light or dark conditions at multiple air temperatures ranging from 16oC to 24oC. Maximum germination consistently occurs within 10 days after sowing. Cultivar differences are substantial as ‘Temptress Orange’ resulted in nearly twice germination of ‘Temptress White’ and germinate about one day faster than the white cultivar (Tables 1 and 4). These findings are of value to cut flower producers in that they suggest ease of germination for this species across a range of environmental conditions such that special equipment or care does not seem to be necessary to achieve maximum germination, which is predominantly influenced by genetic potential and/or seed quality. Considering the results of the seedling development study, it is suggested that poppies be allowed to germinate and develop in lower temperatures. Development was visibly reduced in seedlings from the high temperature treatments.
Educational & Outreach Activities
Stolp, K.M. 2006. Optimizing germination of Papaver orientale ‘Temptress’ and fertilization of Eustoma grandiflorum ‘Balboa Rose.’ M.S. Thesis, Kansas State University.
Electronic publication of results to www.hightunnels.org and submission to ASCFG’s Cut Flower Quarterly is planned.
Organic versus Conventional Fertilization of Lisianthus
Fertilization requirements for lisianthus ‘Balboa Rose’ were established using both organic and conventional soluble and slow release fertilizers. This research extends recommendations in the literature to include organic fertilizer alternatives for this important cut flower crop, and provides rates of application appropriate for constant liquid feed delivery systems, which were previously not documented. This research was subject to a unique problem associated with organic fertilizer use: lack of knowledge of, or control over, the release rate of nutrients from solid organic sources. However, the soluble organic fertilizer used (Daniel’s 10-4-3) offers organic farmers a consistent, reliable nutrient source alternative that can be easily applied through a drip / soluble feed system.
Germination and Seedling Development of Giant Oriental Poppy
Because we were unable to assure consistent germination of this species for our own use and found that growers were also having trouble doing so, research was conducted to accurately define germination requirements for giant Oriental poppy, a specialty cut flower of increasing popularity and lucrative market potential. Our research delineates the range of environmental and cultural conditions under which this cultivar will germinate and identifies a potential difficulty for producers, which is color-specific germination differences.
Other Project Impacts
The unfortunate microburst that destroyed the Haygrove high tunnels at the Easter Kansas Horticulture Research and Education Center in August 2004, as well as reconstruction and management of the structures before and after, has resulted in insights about the limitations of using Haygrove high tunnels in the Midwest. This information is useful to farmers who are considering construction of high tunnels. Other outcomes are listed in the “Publications/Outreach” in this report.
No economic analysis conducted for this project.
Cut flower grower Vicki Stamback, owner and operator of Bear Creek Farms in Stillwater, Oklahoma, visited the Haygrove high tunnels at the Eastern Kansas Horticulture Research and Extension Center, and toured three market farming operations in Eastern Kansas with four students and Williams in April 2006. We discussed sustainable fertilizer use and results of the poppy germination research (which she helped initiate), and brainstormed further research areas. In particular, Vicki decided against construction of Haygrove high tunnels in her upcoming farm expansion project based on our experiences.
Areas needing additional study
Simplifying the use of organic fertilizers would greatly increase their adoption by cut flower growers, who typically manage culture of a hundred or more species/cultivars of plants. The lack of consistent nutrient release patterns makes their use difficult on non-fertile soils, and difficulty of knowing how much fertilizer to apply (because of lack of recommendations for a given species, lack of appropriate soil testing procedures to allow for accurate recommendations to be made, and lack of knowledge of nutrient release of the hundreds of organic materials available) are often cited reasons by producers for over-application of nutrients and lack of adoption of non-conventional fertilizer sources.