IMPROVEMENT OF THE PRODUCTIVITY OF Foeniculum vulgare UNDER SALT STRESS BY USING PHOSPHATE SOLUBILIZING BACTERIA AS BIOFERTILIZATION

Effects of phosphate solubilizing bacteria (PSB) and salt stress on soil
biological activity, growth, essential oil persent and yield, and nutrient acquisition of
fruits fennel plants (Foeniculum vulgare) were investigated in pot experiments in two
seasons. Under the nonsaline (irrigation with tap water) conditions (Oppm) and
moderate salt (irrigation with saline water 1500 and 3000 ppm) the rhizosphere
colonization showed a significantly higher bacterial, fungal, and actinomycetes counts
than the high salt (4500 ppm). The colonization by PSB decreased with increasing
salinity level. Soil enzyme activities (phosphatase and dehydrogenase) decreased
with increasing soil salinity, however, the degree of inhibition· varied among the
enzymes assayed and the amount of salt added. Enzyme activities were higher in the
rhizosphere of fennel plants inoculated with f'SB than in uninoculated plants.
Inoculation with Bacillus. megalerium contributed positively to plant nutrient content,
growth, essential oil, and mineral nutrition under all salinity levels. Inoculation with
PSB induced significantly increase in N, P, K content and protein accumulation as
compared to uninoculated treatments. Generally, concentration of all nutrients and
protein accumulation decreased as the salinity levels increased in both inoculated and
uninoculated treatments. Under nonsaline condition, fruit contents of Cu, Fe, and Zn
were higher for treatments inoculated with PSB than uninoculated treatments, but the
differences were not significant for Cu at the hi\lh salinity level (4500 ppm). The
concentration of Na, Mg and Ca increased in fruits under irrigation with saline water
compared to the control. The results suggest tnat fennel plants benefited from
inoculation with biofertilizers phosphate solubilizir g bacteria especially under salt
stress.