Chrysanthemum cultivation in expanded clay. I. Effect of the nitrogen-phosphorus-potassium ratio in the nutrient solution

The hydroponic technique using expanded clay for the production of chrysant hemum was studied for possible use by Brazilian flower producers. Eight var ying nutrient solution nitrogen (N):phosphorus (P):potassium (K) ratio trea tments in a randomized block configuration with four replications were used . Six of the treatments supplied the same solution over the entire experime ntal period. The N:P:K ratios in the nutrient solution compared were: 1.0:0 .3:1.0, 1.0:0.3:1.5, 1.0:0.3:2.0, 1.0:0.3:2.5, 1.5:0.3:1.0, and 2.0:0.3:1.0 . The other two treatments consisted of N:P:K ratios of 2.0:0.3:1.0 during the juvenile stage and 1.0:0.3:1.5 or 1.0:0.3:2.0 ratios during the reprodu ctive stage. There were two or three daily irrigations depending on plant n eed. The electrical conductivity (EC) and pH of the nutrient solution were checked once each day and the nutrient solution was chanced when 50% deplet ed. The plants were crown to the two-stem stage under 50 long and 4.0 short days. Harvest was made 115 days after plant establishment. There were not expressive differences in plant characteristics among the treatments. The 1 .0:0.3:2.5 N:P:K ratio gave the highest flower numbers per stem, stem lengt h, and fresh and dry weights per plant.