INFLUENCE OF PHOSPHORUS, POTASSIUM AND YEAST NUTRITION ON GROWTH, FLOWERING AND CHEMICAL COMPOSITION OF TUBEROSE.

Two field experiments were carried out at the Vegetable and Ornamental Plants Dept., Faculty of Agriculture, Mansoura Univ., Egypt, during the two successive seasons of 2008/2009 and 2009/2010 to study the influence of calcium superphosphate at 1.05 and 2.10 g / plant, potassium sulphate at 0.70 and1.40 g / plant, and yeast extract at 1, 2 and 3 g/L as foliar sprays once monthly for three months on growth, flowering and chemical composition of tuberose plant.
Yeast extract at 3 g / L was very effective in stimulating vegetative growth and flower as well as mineral content, the use of calcium superphosphate at 1.05 g / plant has led to increase the leaf area, dry weight of leaves, and increase the length and number of flowers. While, the use of concentration 2.10 g / plant led to the shortest period from planting to flowering and harvest in both seasons. The use of potassium sulfate at 0.70 g / plant has led to increase dry weight of leaves and decreased period from planting to flowering and harvest. Besides, the length of spike and the number of flowers / spike and total chlorophyll in the leaves were increased. While, the use of concentration 1.40 g / plant has led to increase the mineral content in the leaves.
Application of yeast extract at 3g/L combined with calcium superphosphate at 2.10g, potassium  sulphate at 1.40g  in addition to yeast extract at 3g/L, calcium superphosphate 2.10g and potassium sulphate 0.70 g induced higher values concerning (leaf area and dry weight ) over all the other treatments. Moreover, least number of days until harvesting was achieved. Flower quality had higher values and flower number  were increased. In addition photosynthetic pigments studied (chlorophyll a+b) when compared with other treatments.
Thus, it could be concluded that spraying tuberose plants with yeast extract (3g/L), calcium superphosphate (1.05g) and potassium sulphate (0.70g / plant) once monthly for three months induced the best vegetative growth and flower quality and economically save about half doses of phosphorus and potassium fertilizer.
Yeast nutrition is considered as a potent, safety and costless natural stimulator.