Effects of four elements on color, yield and vase life of tree 'fern' (Asparagus virgatus)

摘要

Tree "fern" is the second most popular cut foliage crop produced in Florida, but almost nothing is known about its nutritional requirements. This crop frequently has problems with chlorosis that can significantly reduce the yield of harvestable stems. Plants from seed were grown in a soilless medium (Vergro Container Mix A without trace element charges, Verlite Co., Tampa, FL) in 25.4-cm diameter plastic cans for two years. Cans were held in a shadehouse covered with 60 percent light exclusion fabric and were watered with overhead irrigation 3 times/week during the winter and daily the rest of the year. N, P and K were supplied using 20-3-8.3 or 14-6.2-11.6 controlled-release fertilizers without micronutrients (Nutricote~(R) 20-7-10, Plantco, Brampton, Ontario; Osmocote~(R) 14-14-14, The Scotts Company, Marysville, OH) at the rate of 2,928 kg N per ha [2614 lbs N per acre] per year. All pots received boron, copper, and molybdenum but iron, magnesium, manganese, and zinc were applied at varying rates from 0 to a maximum of 90, 336, 45 and 22 kg centre dot ha~(-1) centre dot yr~(-1) [0 to 80, 300, 40 and 20 lbs/acre/year], respectively. Micronutrient applications did not affect average stem weights, but yields (number and weight of stems) were affected by Fe. Tissue content of the micronutrients increased with increasing application rate, especially for Mn. Chlorosis was most closely associated with low Mn content (r = 0.7, P <= 0.0001). Vase life of harvested stems was generally unaffected by treatments.