EFFECT OF SOME PRE AND POSTHARVEST TREATMENTS ON THE KEEPING QUALITY OF POINSETTIA CUT FLOWERS: I: EFFECT OF DIFFERENT FERTILIZATION REGIMES AND IRRIGATION LEVELS ON THE VEGETATIVE, ROOT GROWTH, FLOWERING AND CHEMICAL COMPOSITION OF PLANTS.

The present investigation was carried out during two seasons of 1997/1998 and 1998/1999 at El-Baramon Ornamental Research Station and Laboratory of Veget. and Flor. Dept., Fac. of Agric., MansouraUniv.  The objective of this research aimed to study the effect of Super grow fertilizer at levels of 0.0, 0.3, 0.6 and 0.9 g/plant added once every week, irrigation with amounts of water once per 3 days at the levels of 150, 300, 450 and 600 ml/plant and their interactions on the vegetative and root growth, flowering and chemical composition of poinsettia plants.
The obtained results indicated that Super Grow fertilizer at 0.9 g/plant significantly increased plant height, number of leaves, dry weight of vegetative parts and roots, diameter of flowers, number of bracts and percentages of nitrogen, phosphorus and potassium in the leaves over control and the other treatments in both seasons.
In addition increments in plant height, number of leaves, dry weight of vegetative parts, diameter of flowers, number of bracts and potassium % in the leaves were achieved with irrigation level at 450 ml/plant.  Data revealed also that increasing the level of irrigation to 600 ml/plant resulted significantly increased dry weight of roots and phosphorus % in the leaves over the other treatments in both seasons.
Concerning the interaction between the fertilization and irrigation treatments, the obtained results indicated that application of the fertilizer at 0.9 g/plant combined with the irrigation level at 450 ml/plant significantly increase vegetative and roots parts as well as flowers measurements, as well as the phosphorus and potassium % in the leaves over the other treatments in both seasons.
The obtained results revealed the superiority of the treatment of applying Super Grow fertilizer at 0.9 g/plant once every week combined with irrigation level at 450 ml/plant once per 3 days weekly to obtain the best vegetative growth and flowering characteristics of poinsettia plants.