Phosphorus nutrition of tobacco seedlings grown in greenhouse float culture 1

Abstract Little work has been done investigating phosphorus (P) nutrition in tobacco seedling production. Three greenhouse experiments were conducted in 1993 and 1994 to determine the influence of P on seedling growth. Treatments consisted of fertilizers containing from 0 to 10% phosphorus. Growth parameters measured in all experiments included seedling dry weight, stem length, and tissue P concentration. Reducing P rate did not affect any growth parameters until the solution nitrogen (N): P ratio became less than 20: 1. The 0 P treatment did not produce any transplantable seedlings in two of three experiments. Final seedling usability was not affected as long as at least a 20: 1: 20 ratio fertilizer was used. Seedling growth in the field, as well as final leaf yield, was not affected by reducing P from 10% to 1%. Data suggest that previous greenhouse fertility recommendations contained excess phosphorus and should be reduced to at least a 20: 5: 20 ratio fertilizer.