Mounira M. Bishara and Nader R. Habashy( 2014). Alleviating Adverse Effects Of Soil Under Salt Stress By Bio-Inoculants And Applied Phosphate On Onion (Allium Cepa) PlantsJ. Biol. Chem.Environ. Sci., 2014,Vol. 9(3): 491- 515
Abstract: Two techniques were carried out to study alleviating adverse effects on growth of onion (Allium cepa L, Giza 20) plants under soil salt stress conditions on a newly reclaimed saline sandy clay loam soil with calcareous effect at South-Tahrir Sector, Al-Behira Governorate, Egypt during the growing season of 2012. The first technique is concerned with the efficiency of inoculation with AM fungi Glomus mosseae and P-dissolving bacteria (Bacillus megaterium var phosphaticum). The second one using phosphate (at two rates 120 and 270 kg ha-1) in combination with AM fungi and B. megaterium in mitigation of salt effect and phosphorus release. Results indicated that mycorrhizal inoculation significantly increased growth parameters as well as nutrient uptake of onion plants than control. The extent of bioinoculants response on plant growth as well as AMF (arbuscular mycorrhizal fungi) root colonization varied with Bacillus megaterium and the increase in phosphate rate. Various parameters such as total chlorophyll, mycorrhizal spores number and AMF infection percentages in plant roots greatly affected by AMF inoculation especially when combined with B. megaterium at the same phosphate rate. Greater P acquisition and yield was observed with dual combination (G. mosseae and B. megaterium) that possibly be responsible for protecting plants from salt stress and release Phosphorus from the soil. Although nitrogen, potassium, calcium and Sodium contents also varied with increasing phosphate rate in bioinoculants treated plants over control. Overall results showed that AMF colonization accompanied with P-dissolving bacteria improves host plant mineral concentration and thereby increases the growth, yield and nutrient uptake of onion ameliorating the harmful effect at salinity stress and calcium carbonate. The density number of B. megaterium and percentage of mycrorrhizal colonization in rhizosphere of onion plant was slightly affected by the phosphate application at both rates. Associated achievements of B. megaterium seemed to benefit symbiosis between mycrorrhizal fungi and onion plants grown under salt stresses and calcareous effect. Enzyme activities (Dehydrogenase, Phosphatase and Nitrogenase) in soil were varied as a result of inoculation under different treatments.
Keywords: (Glomus mosseae, Bacillus megaterium, Phosphate, Onion plants, Salt stress , Calcareous affected soil. )
