Effect of Rhizobacteria and Water Quality on Some Soil Properties and Nutrient Uptake of Barley under Water Stress

A GREENHOUSE pot experiment was conducted to study the effect of phosphate solubilizing bacteria (Azospirillum brasilenseAC1 and Bacillus subtilis AC2) in combination with different water resources (River Nile, El-Salam Canal and diluted sea waters, 1:10 ) and soil moisture depletion, SMD, levels (25, 50 and 75% of the soil field capacity, FC) on some soil properties (Soil pH, EC, available P and total bacterial counts) and barley (Hordeum vulgare var. Giza 28) grain yield and NPK uptake. The results indicated that use of diluted sea water for irrigation significantly reduced soil available P as compared to El-Salam canal and Nile waters. It also significantly increased soil pH values compared to Nile water. The results showed also that utilization of A. brasilense strain as inoculant for barley seeds significantly increased soil available P and decreased soil pH values compared to B. subtilis strain. Irrigating barley plants with the different water resources after depletion of 50% from soil FC significantly increased available P and decreased pH value as compared to 25 and 75% SMD levels. Soil salinity was found to be significantly decreased by irrigating the plants after SMD of 50 and 75% compared to 25%. The highest soil available P and EC were obtained with the treatments Nile water + A. brasilense + 50% SMD and diluted sea water + B. subtilis + 25% SMD level, respectively. On the other hand, the maximum pH value was recorded in the treatment El-Salam canal water + B. subtilis + 25% SMD level. Counts of total bacteria in the rhizospheric soil of barley increased with increasing growth period reaching their highest after 90 days from sowing date. After that, the counts markedly decreased reaching their lowest figures after 120 days. However, total rhizospheric bacterial counts decreased with increasing SMD level from 25 to 75%.
Utilization of diluted sea water for irrigating barley plants significantly decreased grain yield and NPK uptake as compared to the Nile water. The higher the salinity of irrigation water, the lower were the values of grain yield and K uptake. Inoculating barley seedswith A. brasilense AC1 significantly increased barley grain N uptake compared to B. subtilis AC2. Grain yield and NPK uptake were found to be significantly reduced with increasing level of SMD from 25% to 75% FC. The highest grain yield and N uptake values were obtained with the treatment El-Salam canal water + A. brasilense AC1 + 25% SMD level. On the other hand, the highest grain P and K uptake were recorded under the treatments Nile water + A. brasilense AC1 + 25% SMD level and Nile water + B. subtilis AC2 + 25% SMD level, respectively.