EFFECTS OF NUTRIENT SOLUTION MANAGEMENT AND METHODS OF STORAGE AND DISTRIBUTION ON FLOWERING AND QUALITY OF CUT IRIS, TULIP AND LILY

Abstract

Flowering was slightly accelerated when iris was grown with 10.7:3.9 meq/L N:K and flowering percentage and vase life were increased when it was grown at a higher nitrogen level (17.9:3.9 meq/L N:K). CO2 concentration increased as the postharvest storage period was prolonged. Flowering of tulip was promoted by 14.3:3.9 meq/L N:K and internode diameter was significantly increased. Flowering of tulip, cultured with 10.7:3.9 meq/L N:K, 12.1:5.1 meq/L N:K and 14.3:3.9 meq/L N:K treatments, was somewhat delayed by postharvest sealing treatment, and quality was also maintained highly. Growth and flowering of lily was not significantly different between treatments. Vase life of the flowers 1-3 was increased (less than 1 day) by the highest nitrogen treatment, 17.9:3.9 meq/L N:K. In case of respiration rate in lily, cultured with 10.7:3.9 meq/L N:K, postharvest lily stored at 3°C was lower than 5°C. INTRODUCTION The cut iris, tulip, and lily are typical export flower crops in Korea. For plants, absorption of nutrient solution is an important factor during growth. Water and minerals are not taken up from a nutrient solution in the same proportion in which the components are present. The rate of absorption depends upon the plant, the climatic and environmental conditions such as light intensity and duration, temperature, and humidity, as well as the type of culture and the stage of development of the crop (Shim et al., 2001). The form of the nutrient is also important, for example, ammonium nitrogen has positive effects on the growth and development of carnations, including promotion of flowering time and increasing flowering percentage (Ishida and Masui, 1976). Modified atmosphere packaging (MAP) is widely used for both whole and fresh cut products to extend storability and shelf-life during the marketing period (Kader, 1986; Kim, 1998; Watada, 1997; Watada and Qi, 1999). For roses, with time, CO2 accumulates inside the bag, while the relative oxygen concentration is depleted, with the result that the quality of the flowers is improved (Salunkhe et al., 1990). Therefore, this experiment was performed to determine the effects of nutrient solution management and methods of storage and distribution on post-harvest quality in iris, tulip and lily. MATERIALS AND METHODS Effects of Culture Temperature and Nutrient Solution Management on Postharvest Quality in Cut Iris, Tulip and Lily This experiment was done in a greenhouse with a hydroponic system. Air temperature of the greenhouse was at 26/18°C (max./min.). Bulbs of Iris hollandica ‘Blue Magic’, 9-10 cm in circumference, were stored at 5°C for 8 weeks until planting. Bulbs of Tulipa gesneriana ‘Hollandia’, 10-12 cm in circumference, were stored at 5°C for 9 weeks until planting. Bulbs of Lilium ‘Siberia’, 13-15 cm in circumference, were stored at 5°C for 12 weeks until planting. Water was given during the first one week after planting, then nutrient solutions of four nitrogen and potassium levels were used. The Proc. IX Intl. Symp. on Flower Bulbs Eds.: H. Okubo, W.B. Miller and G.A. Chastagner Acta Hort. 673, ISHS 2005 514 nutrient solutions were as follows (all given as N:K, meq/L of each): 10.7:3.9, 12.1:5.1, 14.3:3.9, and 17.9:3.9. The basic nutrient solution also contained macro elements (P:Ca:Mg = 3.0:8.4:4.0 meq/L) and micro elements (Fe:3.0, Mn:0.5, B:0.5, Zn:0.25, Cu:0.03, Mo:0.05 ppm). The nutrient solution was given once per week during the experiment. The pH was maintained 6.5-6.7 and EC was 1.3-1.4 mmho/cm. Plant height, days to flowering, flowering rate, longevity, and diameter of the internode were measured. Effects of Storage and Distribution Conditions on the Postharvest Physiology of Iris, Tulip and Lily Grown in Different Nutrient Conditions Effect of modified atmospheres (MA) on flower longevity and possible interaction with nutrient solution composition was studied. Cut iris was stored at 0°C for pre-cooling after harvest. After pre-cooling, one cut iris was placed in a 1L sealed cylinder, and then, two kinds of gas (MAI: CO2 50% + O2 50%, MAII: CO2 5% + O2 3%) were introduced into the cylinder (15 ml/min for 1 minute). Also, cut iris sealed into cylinders without introduction of gas (MAIII) was dipped in distilled water. The control was dipping in distilled water with cut iris in open air. All treatments were stored at 4°C for 4 days, then the flowering degree and quality and CO2 concentration were measured. Cut tulip was treated with the two gasses, as described above. All treatments were stored at 4°C for 4 days, then the flower developmental index was measured. Flower development was evaluated visually using a scale (1 = green flower bud, 5 = full flowering). The flowering index was determined by multiplying the number of stems at each index value then dividing by the total number of stems. Cut lilies grown with the different nutrient solutions were stored at two temperatures (3 or 5°C) for 4 days, and then, stored at 6°C in a dry or wet condition to simulate transport. Respiration rate was measured every 4 days. Respiration rate was measured by gas production that was calculated from an analysis of 1 ml samples of the head space gas accumulated in 1.5 L chamber in which a cut lily was placed. Three replications were used in each treatment. Gas was analyzed by gas chromatography (GC) of which the operating condition is shown in Table 1. RESULTS AND DISCUSSION Effects of Culture Temperature and Nutrient Solution Management on Postharvest Quality in Cut Iris, Tulip and Lily Flowering was accelerated when iris was grown with 10.7:3.9 meq/L N:K as compared with other treatments (Table 2). The flowering percentage was increased when iris was grown with the highest nitrogen level (17.9:3.9 meq/L N:K) treatment. Also flower development was slightly increased by the highest nitrogen treatment. Nitrogen had no effect on plant height, leaf length and width, stem diameter, and degree of senescence and flower longevity. Plant height was decreased and plants flowered slightly faster when tulip was grown with 14.3 meq/L nitrogen as compared with other treatments (Table 3). Growth and flowering of lily were not significantly different between treatments but plant height was slightly decreased when lily was grown at the highest nitrogen level (Table 4). Leaf number and flower width were slightly increased by the 14.3:3.9 meq/L N:K treatment, but these differences are probably of no commercial significance. Vase life of flowers 1 to 3 was prolonged by less than 1 day by the highest nitrogen treatment. Nitrogen had no effect on lily stem diameter, days to flowering, leaf length and width, and flower length and number. Effects of Storage and Distribution Conditions on the Postharvest Physiology of Iris, Tulip and Lily Grown in Different Nutrient Conditions For iris, CO2 concentration increased as the postharvest storage period was prolonged (Fig. 1). Especially, CO2 concentration showed the lowest degree at MAIII treatment as compared with other treatments, and we could find that flowering was