Effect of N concentration and NH4+ : NO3- ratio of nutrient solution on growth and flowering of salvia, petunia, and ageratum.

摘要

The effects of N concentrations and NH4+ : NO3- ratios in nutrient solution on plug seedling growth and flowering of S. splendens cv. Salsa Scarlet Bicolor, P. hybrida cv. White Madness and A. houstonianum cv. Blue Puffs were investigated. N concentrations used were 7 and 14 me/litre, and NH4+ : NO3- ratios (% in me/litre) used were 0 : 100, 25 : 75, and 50 : 50 in each N concentration. Seeds were sown in 200-cell plug trays and germinated on a mist propagation bed. Seedlings were grown in a glasshouse and were supplied with nutrient solutions by an overhead irrigation. After growth measurement, plug seedlings were transplanted to plastic pots of 6 cm diameter and flowering, number of flowers and growth characteristics were examined. In seedlingsof S. splendens, P. hybrida and A. houstonianum, plant height and both fresh and dry weights were significantly increased at 14 me N/litre concentration. After transplanting, days to flowering in petunia was shortest at low N concentration and 25 : 75 NH4+ : NO3- ratio. At higher NH4+ concentrations, it showed dark green leaves and showed a significant difference in total chlorophyll content. For S. splendens and A. houstonianum, days to flowering were not significantly different. It seemed that the optimum ratio of NH4+ : NO3- depends on growth stage of each species.