Nitrogen Concentration in Nutrient Solution, Post Harvest Life and Flowers Commercial Quality in Hydroponic Gerbera

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1 Nitroen Concentration in Nutrient Solution, Post Harvest Life and Flowers Coercial Quality in Hydroponic Gerbera L. Mascarini and G. Lorenzo Cátedra de Floricultura Facultad de Aronomía Universidad de Buenos Aires Av. San Martín 4453 (1417) Ciudad Autónoma de Buenos Aires Arentina F. Vilella Cátedra de Producción Veetal Facultad de Aronomía Universidad de Buenos Aires Av. San Martín 4453 (1417) Ciudad Autónoma de Buenos Aires Arentina Keywords: Nitrate, soilless culture, Gerbera jamesonii INTRODUCTION Gerbera jamesonii is an Asteraceae. They are cultivated as pot plant or cut flower. In the last case, the crop may extend six or seven years, but coercially it is not recoended to row them beyond three years, because of the reduction of yield and quality (Mascarini, 1998). With the soilless culture technique it is possible to reach hiher yield and better quality than with traditional culture (Bañón Arias et al., 1993). In a crop on inert substrate, all mineral nutrients are applied externally, in order to ensure the rowth and development of the plants. In our country, many crops are carried out in soil, but there is a stron expansion of hydroponic systems (Mascarini, 1998). The coercial quality is determined accordin to the followin variables: stem lenth, capitulum diameter, stem riidity and visual aspect (Bañón Arias et al., 1993). Before harvest there are many factors that potentially may affect the vase life, like water status, type of substrate, nutritional status, environmental conditions, hour of harvest, ae of plant, etc. (Bañón Arias et al., 1993; Savvas and Gizas, 2002). In a soilles crop, the optimum nutrient status of the plant may not be associated to the maximum delivery. In plants cultivates under a hiher concentration of elements in the nutrient solution increased dry weiht but reduced stem lenth and number of flowers (De Kreij and van Os; 1988). Nitroen excess reduces vase life and tolerance to transportation (Bañón Arias et al., 1993). The aim of this work was to determine if different nitroen content (N-NO 3 - ) in the nutrient solution affect the productivity, coercial quality and vase life of erbera cut flowers. MATERIALS AND METHODS The trial was carried out in Faculty of Aronomy, University of Buenos Aires, Arentina. The crop was Gerbera jamesonii Sunway (Florist ), In January of 2002 the plants were planted on perlite (10) in individual pots of 10 L. The plant density was 7 plants m -2. The crop was placed in a polyethilene covered steel reenhouse, with automatic control of heatin and ventilation. The irriation and fertilization were applied by drippers. There were three treatments: N-: 80 ppm, Nn: 140 ppm, N+: 190 ppm of N- NO 3 -. The rest of the nutrient elements were kept constant. The ph was and EC was 1.5 ds m -2 (+/- 1). The experimental desin was in blocks completely randomized, each treatment had five replications and a total of fifteen plants. The flowers were harvested as soon as they reached coercial maturity. Each flower was identified and recorded. Quality variables measured were: stem lenth, capitulum diameter, stem diameter (10 below the capitulum) and total fresh weiht. Vase life was evaluated for all harvested flowers, in water at environmental temperature (around 20 C) and natural dayliht. The end of vase life was established accordin to the ravitropic fall of the inflorescence or abscission of flowers or wiltin. The data was analyzed by analysis of variance. RESULTS AND DISCUSSION Hiher concentrations of nitroen increased the production of flowers but the averae Proc. IS on Soilless Cult. and Hydroponics Ed: M. Urrestarazu Gavilán Acta Hort. 697 ISHS

2 values of quality variables and vase life did not show sinificant differences. The plants under a hiher nitroen level produced more flowers; Nn tended to a hiher yield, but were observed no sinificant differences (Table 1). Only stem was sinificantly loner in Nn and N- (52.0 and 54.6 respectively) than in N+ (48.6 ) (Table 2). However, effects on stem lenth, capitulum diameter, stem diameter and fresh weiht, could be analyzed when the data were raned and cateorized. Under N-, 7 of the flowers had stem lenth loner than 50. For N+ and Nn, these percentaes were and 55% (Fi. 1). Capitulum diameter showed inverse tendency, the plants under hiher nitroen concentration had hiher percentae of flowers with the inflorescence reater than 10 (Fi. 2). Stem diameter and total fresh weiht did not show a definite tendency (Fis. 3 and 4). It has been demonstrated that erbera is tolerant to a wide rane of elemental ratios. So the optimum N : P 2 O 5 : K 2 O ratio recoended can vary from 1:1:1 to 3:1:5 (Roers and Tija, 1990). Therefore, differences amon treatments in our trial could be due to interactions with other macro or micro nutrients. There were evidence that plants rowin with hih availability of N-NO 3 - are more compact, which miht be related to a hiher ph in the substrate, and a differential absorption of some micronutrients. A hih ph and restricted assimilation of Mn, P and Fe were related to shorter stems and low production of flowers (Saavas and Gizas, 2002). In chrysanthemum, a hiher availability of nitroen in nutrient solution has been associated to the reduction of plant rowth (Barbosa et al., 2000). The rane of vase life was improved with hiher dose of nitroen, at least between the concentrations analyzed (Fi. 5). Plants under N- produced more than 5 of the flowers with less than 8 days of vase life, while this percentae for Nn and N+ were 47% and 41%, respectively. Althouh the percentae of flowers that showed more than 14 days of vase life was similar in N- and N+, many of the N- was smallest, then the coercial quality was lower in relation to Nn and N+. De Kreij (1988) cited that hih N level in nutrient solution tended to reduce vase life, but there were not sinificant differences. Dufault (1990) reported that N level affected as quantity as quality of flowers, althouh hiher doses of nitroen increased yield, but also percentae of discarded flowers was hiher. CONCLUSION Hiher concentrations of nitroen increased the production of flowers but the mean quality index and the vase life did not show sinificant differences. However, the uniformness of the production was improved by a hiher availability of nitroen. Lower level of N tended to reduce the vase life. Further research is needed to determine in each season the optimum doses of N which maximize quality and productivity. Literature Cited Bañon Arias, S., Romo Cifuentes, D., Fernandez Hernandez, J.A. and Gonzalez Benavente Garcia, A Gerbera, lilium, tulipán y rosa. Ed: Mundiprensa. Madrid, España. 250 pp. Barbosa, J.G., Kampf, A.N., Martines, H.E.P., Koller, O.C. and Bohen, H Chrysanthemum cultivation in expanded clay. I. Effect of the Nitroen-Phosphorus- Potassium ratio in nutrient solution. Journal of Plant Nutrition 23(9): De Kreij, C. and Van Os, PC Production and quality of erbera in rockwool as affected by electrical conductivity of the nutrient solution. ISOCS Proceedins, Dufault, R.J., Phillips, T.L. and Kelly, J.W Nitroen and potassium fertility and plant populations influence field production of erbera. HortScience 25(12): Mascarini, L El cultivo de la erbera en sustrato. Horticultura Internacional 19: Mascarini, L., Delfino, O.S. and Vilella, F Evapotranspiration of two Gerbera jamesonii cultivars in hydroponics: adjustment of models for reenhouses. Acta Hort. 554: Papadopoulou, E., Gerasopoulos, D. and Maloupa, E Effect of the substrate and frequency of irriation on rowth, yield and quality of Gerbera jamesonii. Bolus cultivated in pots. Aricoltura Mediterranea 126: 3,

3 Roers, M.N. and Tjia, B.O Gerbera production. Ed: Timber Press INC. Portland, Oreon, USA. 116 pp. Savvas, D. and Gizas, G Response of hydroponically rown erbera to nutrient solution recyclin and different nutrient cation ratios. Scientia Horticulturae 96: Steel, R.G.D. and Torrie, J.H Bioestadística: principios y procedimientos. Ed. McGraw-Hill, México DF, México. 622pp. Tables Table 1. Production of flowers per 3 plants under different N-NO 3 concentrations in the nutrient solution in a erbera cut flower soilless crop. Harvest period: 8/3/2004 to 3/6/2004. Similar letter in the same column indicate no sinificant difference (p=0.05). Treatment Number of flowers (averae x 3 plants; n=5) Number of flowers / plant Confidence limits (p=0.05%; n=5) N- : 80 ppm N-NO a 3.2 a Nn: 140 ppm N-NO a 4.3 a N+: 190 ppm N-NO a 3.1 a Table 2. Averae values for the quality index variables under different N-NO 3 solution in a erbera cut flower soilless crop. Harvest period: 8/3/2004 to 3/6/2004. Different letters in the same column indicate sinificant difference. (p=0.05). TREATMENT STEM LENGHT CAPITULUM DIAMETER STEM DIAMETER TOTAL FRESH WEIGHT TOTAL VASE LIFE Days N-: 80 ppm N-NO a 9.55 ns 6.54 ns ns ns Nn: 140 ppm N-NO a 9.67 ns 6.71 ns ns 9.19 ns N+: 190 ppm N-NO b 9.59 ns 6.67 ns ns ns 373

4 Fiures <40 40 a a a a 60 Rane of stem lenht 60 a 65 >65 less than 9 9 to 10 more than 10 Rane of capitulum diameter Fi. 1. Stem lenth of flowers produced under different N-NO 3 solution in a erbera cut flower soilless crop. Bars shows % of the total of harvested flowers. Harvest period: 8/3/2004 to 3/6/2004. Fi. 2. Capitulum diameter of flowers produced under different N-NO 3 solution in a erbera cut flower soilless crop. Bars shows % of the total of harvested flowers. Harvest period: 8/3/2004 to 3/6/2004. % of flowers % of flowers 4,5 to 5 5 to 5,5 5,5 to 6 6 to 6,5 Stem diameter 6,5 to 7 >7 <20 20 to to to 35 Total f resh weiht 35 to to 45 Fi. 3. Stem diameter of flowers produced under different N-NO 3 solution in a erbera cut flower soilless crop. Bars show % of the total of harvested flowers. Harvest period: 8/3/2004 to 3/6/2004. Fi. 4. Total fresh weiht of flowers produced under different N-NO 3 solution in a erbera cut flower soilless crop. Bars show % of the total of harvested flowers. Harvest period: 8/3/2004 to 3/6/

5 less than 8 days 8 to 14 days more than 14 days Total vase life Fi. 5. Vase life of flowers produced under different N-NO3 solution in a erbera cut flower soilless crop. Bars show % of the total of harvested flowers. Harvest period: 8/3/2004 to 3/6/