The main objective of this study was to determine the response of sex
expression and yield as well as its quality characteristics 0 f spinach, in relation to
planting date, biofertilizer and GA3 treatments. Two field experiments were carried out
during 2001/2002 and 2002/ 2003 winter seasons at the Agricultural Research
Station, Faculty of Agriculture, Alexandria University, to investigate the effects of
planting date (October and December) and the application of biofertilizer (Halex2)
and/or GA3 spray (25 ppm) as well as their interaction on vegetative growth, sex
expression, chemical composition, yield of fresh leaves and its quality and seed
production of spinach plant, cv. Saloniky. The obtained results revealed that: 1- Sowing spinach seeds early in October significantly increased plant height,
photosynthetic pigments and total sugar contents of leaves and seed yield and its
quality, compared with the late planting date (in December). On the other hand, no
significant differences were detected in number and area of spinach leaves,
nitrogen content and C/N ratio, endogenous phytohormones and yield of fresh
leaves and its quality, due to planting date. 2- Inoculation of spinach seeds with biofertilizer was more pronounced for almost
studied characters, such as vegetative growth, chemical composition and yield of
fresh leaves and its quality, than GA3 and control treatments. In addition,
biofertilizer significantly enhanced both cytokinin and ethylene contents and
reduced GA3 content of leaves. 3- Biofertilizer inoculation significantly increased also the number of vegetative male,
female and monoecious spinach plants and reduced the number of extreme male
plants which was significantly increased with GAJ spraying. Sex expression
response to biofertilizer and/or GA₃, in relation to endogenous hormone changes
was also discussed. 4- The correlation coefficient studies confirmed the relationships between sex
expression and total yield of spinach as well as its quality characteristics, in
relation to the effect of biofertilizer and/or GAJ application, at both planting dates.
5-0n the other hand, the results revealed that GA3 is needed beside biofertilizer
inoculation in order to increase seed production of spinach and to improve its
quality, under either early (October) or late (December) planting dates. 6- It can be recommended the use of biofertilizer (Halex2) for spinach production to
reduce the mineral NPK-fertilizers and to increase the yield of fresh leaves and its
quality, and the use of GA3 beside' biofertilizer to increase seed yield and its
quality.