Fern5 (Asparagus Virgatus)
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Proc. Ha. State Hort. Soc. 112:282-285. 1999. A PEER REVIEWED PAPER EFFECTS OF FOUR ELEMENTS ON COLOR, YIELD AND VASE LIFE OF TREE "FERN5 (ASPARAGUS VIRGATUS) R. H. Stamps and D. K. Rock sium, manganese, zinc) have on tree fern yield and posthar University of Florida, IFAS vest longevity. Mid-Florida Research and Education Center 2725 Binion Road Materials and Methods Apopka, FL 32703-8504 Plants used in this experiment were grown from seed Additional index words. Chlorosis, postharvest, tiki "fern", iron, sown 11 Jan. 1995 in 30.5 x 61 cm [12 x 24 inch] flats filled manganese, magnesium, zinc. with soilless growing medium (Fafard Mix #4, Conrad Fafard, Inc., Springfield, MA) and placed under clear plastic covers Abstract. Tree "fern" is the second most popular cut foliage in an unshaded greenhouse. Seedlings were transplanted crop produced in Florida, but almost nothing is known about into 10-cm [4-inch] plastic pots filled with soilless growing its nutritional requirements. This crop frequently has prob medium (Vergro Container Mix A without trace element lems with chlorosis that can significantly reduce the yield of charges, Verlite Company, Tampa, FL). harvestable stems. Plants from seed were grown in a soilless One year after seeds were sown, plants were repotted to medium (Vergro Container Mix A without trace element charg 15-cm [6-inch] diameter nursery cans filled with the same es, Verlite Co., Tampa, FL) in 25.4-cm diameter plastic cans for soilless growing medium (Vergro Container Mix A without two years. Cans were held in a shadehouse covered with 60% trace element charges) and placed on black polypropylene light exclusion fabric and were watered with overhead irriga ground cloth in a shadehouse covered with 60% light exclu tion 3 times/week during the winter and daily the rest of the sion polypropylene shade fabric. Six months after repotting, year. N, P and K were supplied using 20-3-8.3 or 14-6.2-11.6 controlled-release fertilizers without micronutrients (Nutri- plants were potted up to 25.4-cm [10-inch] diameter nursery cote® 20-7-10, Plantco, Brampton, Ontario; Osmocote® 14-14- cans, again using the same soilless medium, and nutrient 14, The Scotts Company, Marysville, OH) at the rate of 2,928 kg treatments were initiated. Initial medium Fe, Mg, Mn, and Zn N per ha [2614 lbs N per acre] per year. All pots received boron, levels were 0.19,113, 0.05 and 0.02 mg-kg-1 [ppm], respective copper, and molybdenum but iron, magnesium, manganese, ly. Initial and final medium pHs were 7.1 and 6.8, respectively. and zinc were applied at varying rates from 0 to a maximum of N, P and K were supplied using controlled-release fertiliz 90, 336, 45 and 22 kgha 1yr1 [0 to 80, 300, 40 and 20 lbs/acre/ ers without micronutrients (Nutricote® 20-7-10, type 180, year], respectively. Micronutrient applications did not affect Plantco, Brampton, Ontario; Osmocote® 14-14-14, type 3-4 average stem weights, but yields (number and weight of month, The Scotts Company, Marysville, OH) at the rate of stems) were affected by Fe. Tissue content of the micronutri 2,928 kg N per ha [2,614 lbs N/acre] per year. All pots re ents increased with increasing application rate, especially for Mn. Chlorosis was most closely associated with low Mn con ceived the same amounts of boron, copper, and molybde tent (r = 0.7, P< 0.0001). Vase life of harvested stems was gen num, 0.56, 5.6, and 1.7 kg-ha^yr1 [0.5, 5, 1.5 lbs/acre/year], erally unaffected by treatments. respectively; but iron, magnesium, manganese, and zinc were applied at varying rates from 0 to a maximum of 90, 336, 45, Florida produces over 78% of all cut cultivated greens and 22 kg-ha^yr1 [0 to 80, 300, 40, and 20 lbs/acre/year], re grown in the United States (U.S. Dept. Agr., 1999). Tree spectively (Table 1). Sulfate sources of Fe, Mg, Mn and Zn "fern" {Asparagus virgatusBak.), also known in the trade as tiki were applied in 150 mL [4.4 oz] of water per pot. Monthly ap "fern", is the second most commonly grown cut foliage in plication of elements began 23 Sept. 1996 and continued for Florida (Stamps, 1994). Tree fern is an ornamental asparagus two years. No pesticides containing micronutrients were used related to edible asparagus and is, therefore, not a true fern. on this crop. Pots were arranged in a randomized complete Tree fern is a relatively new crop and almost nothing is known block design with Ox, 2x and 4x treatments replicated six about its nutritional requirements. Growers have reported times and lx rate replicated 24 times. problems with chlorosis (yellowing) of cladophylls (portions In winter, polyethylene film covering the shadehouse, of stems modified to function as leaves). While some of these combined with forced air heaters, maintained temperatures problems are probably caused by damage due to mites and above 4°C [39.2°F]. A solid set overhead irrigation system fungal pathogens, some may be due to micronutrient defi provided 1.2 cm [Vi inch] of water three times a week when ciencies and/or toxicities. The purpose of this experiment the shadehouse was covered with polyethylene and daily dur was to determine what effects four nutrients (iron, magne- ing the rest of the year. One to three stems per plant (depending on availability) were harvested in the afternoon for vase life studies on 25 Florida Agricultural Experiment Station Journal Series No. R-07176. The Nov. 1996, 22 July 1997 and 31 Dec. 1997. Stems were bun authors sincerely thank Dr. Arvel Hunter and Agro Services International, dled according to treatment and held in the shadehouse in Orange City, FL for providing tissue analysis for this study. Mention of a prod temperatures from 27-34°C [80-94°F] until the entire experi uct does not constitute a recommendation or warranty of the product by the ment was cut (an average of one hour). Bundled stems were authors or the University of Florida Institute of Food and Agricultural Scienc es, nor does it imply its approval to the exclusion of other products that may immersed in water, wrapped in polyethylene film and stored also be suitable. in waxed, corrugated fiberboard cartons at 4.4°C [40°F] for 282 Proc. Fla. State Hort. Soc. 112: 1999. Table 1. Nutrient application rates (kg-ha'-yr1 [lb/acre/yr])'. iment, samples were taken for tissue analysis. Filtered wet di gested plant tissue extract was analyzed for Fe, Mn, Mg and Zn Application using atomic absorption spectrometry (Hunter, 1988). level Fe Mg Mn Zn Rate effects on tree fern growth and vase life were deter Ox 0 84 [75] 11.2 [10] 5.6 [5] mined for each element using regression and chi-square anal 22.4 [20] 0 11.2 [10] 5.6 [5] ysis (SAS Institute, Cary, NC). 22.4 [20] 84 [75] 0 5.6 [5] 22.4 [20] 84 [75] 11.2 [10] 0 lx 22.4 [20] 84 [75] 11.2 [10] 5.6 [5] Results and Discussion 22.4 [20] 84 [75] 11.2 [10] 5.6 [5] 22.4 [20] 84 [75] 11.2 [10] 5.6 [5] Yield {harvestable stems and average stem size). Yield response 22.4 [20] 84 [75] 11.2 [10] 5.6 [5] (stem numbers and total fresh weight) to Fe application rates 2x 44.8 [40] 84 [75] 11.2 [10] 5.6 [5] was quadratic with the lowest yields of all nutrient treatments 22.4 [20] 168 [150] 11.2 [10] 5.6 [5] occurring at the Ox and 4x rates (Table 2). Iron application 22.4 [20] 84 [75] 22.4 [20] 5.6 [5] rates did not affect stem size (average stem weights). The re 22.4 [20] 84 [75] 11.2 [10] 11.2 [10] duced yield at the Ox Fe rate suggests Fe is necessary for pro 4x 89.6 [80] 84 [75] 11.2 [10] 5.6 [5] duction of harvestable tree fern stems. However, in a nutrient 22.4 [20] 336 [300] 11.2 [10] 5.6 [5] solution study in which edible asparagus {Asparagus officinalis 22.4 [20] 84 [75] 44.8 [40] 5.6 [5] 22.4 [20] 84 [75] 11.2 [10] 22.4 [20] L.) seedlings were grown without Fe, yield was not reduced (Benson and Paulsen, 1990). Iron deficiency symptoms were z0x, 2x and 4x treatments were replicated six times; lx treatments were rep observed but the relatively short duration of that solution licated 24 times. study (3 months) may have been insufficient for yield reduc tions to occur. The depression in yield at the 4x rate may have 14 days. Upon removal from the cooler, stems were recut 5 been due to the Fe interfering with the Mn for uptake (Brady, cm [2 inches] above the base and placed by treatment in glass 1990; Mills and Jones, Jr., 1996). After Fe at the Ox and 4x jars filled with deionized water in rooms that simulated the rates, the lowest yields were for Mn at those same rates and home/office environment. Room conditions were main possibly for similar reasons. However, Mg, Mn and Zn treat tained at 20 ± 2°C [72 ± 4°F] and 55% ± 5% RH, with 12 hours ments did not affect yield or stem size. The lack of response of light/day at 17 jimol-m^s-1 (107 ft-candles) provided by to added Mg may have been due, at least initially, to the incor cool white fluorescent lamps.