Nitrogen Concentration in Nutrient Solution and Module Volume Effects on the Growth Characters and Yield Potentials of Eggplant Seedlings A. Balliu, G. Sallaku and S. Kuçi Agricultural University of Tirana Tirana Albania Keywords: N concentration, module volume, N recovery efficiency, root:shoot ratio, root:whole plant ratio Abstract The influence of nitrogen concentration in the feeding solution and of module volume on the growth of eggplant seedlings was investigated in experiments conducted in a plastic greenhouse during the spring of 2006. Graded seeds of cv. Aragon F1, were individually sown in two different types of foam trays with a volume of 78 cm 3 /module or 95 cm 3 /module, which were filled with vermiculite. Four N concentrations, respectively 100, 150, 200 and 250 mg L -1 were compared with the same content of phosphorus (40 mg L -1 ) and potassium (250 mg L -1 ). Root, stems and leaf dry matter as well as leaf area were measured and the root:shoot dry weight ratio (RSR) and root:whole palnt weight (RWR) were calculated. Plant N content was determined weekly during the experiment and the N recovery efficiency (N) was computed. After 50 days since sowing, an equal number of seedlings from each treatment were planted into Klasmann grow bags and periodically fed with the same nutrient solution (NPK concentration of 200, 40 and 250 mg L -1 , respectively). The total harvested yield of each plot was recorded. It was found that the increase of the N concentration in the nutrient solution stimulated dry mas accumulation, stem elongation and leaf expansion rate, but decreased RSR and RWR. Plant tissues accumulated more N with increasing N concentration in the feeding solution, but meantime there was a gradual decrease in NRE. The differences observed between treatments at seedling stage were not associated to any significant difference in fruit production of greenhouse-grown plants. INTRODUCTION Most of vegetable crops are now established by transplanting seedlings grown in module trays. The necessity for precise scheduling of the delivery of transplants to commercial growers required that all phases of nursery production are strictly controlled. One of the most effective way of controlling transplant growth is to moderate the fertilisation (Dufault, 1998). Since the nutrient content of the growing medium is generally quite low, plant nutrition depends on the frequency of fertigation and the concentration of the feeding solution. It was found that growth rate of vegetable seedlings was directly related to the nitrogen concentration of the nutrient solution within the range of 100-400 mg L -1 (Wien, 1997). Therefore, it should be possible to regulate the growth rate of vegetable seedlings by controlling the concentration of nitrogen in the growing medium. In this work, the influence of nitrogen concentration in the feeding solution and of module volume on the growth of eggplant seedlings was investigated in experiments conducted in a plastic greenhouse. MATERIALS AND METHODS Graded seeds of eggplant (Solanum melongena L.) cv. Aragon F1, were individually sown in two different types of foam trays with a volume of 78 cm 3 /module or 95 cm 3 /module, which were filled with vermiculite and placed in a plastic greenhouse during the spring of 2006. Four N concentrations, respectively 100, 150, 200 and 250 mg 1373 Proc. IS on Greensys2007 Eds.:S. De Pascale et al. Acta Hort. 801, ISHS 2008