Phosphorus (P) is one of the most important minerals required for plant growth occupying a strong position among soil macro nutrients. Soil P deficiency is often fulfilled by phosphate fertilizers. P deficiency in soils is due to less total P contents in the soil and fixation of added P from chemical fertilizers as well as other organic sources like manures. The response of plant under P stress or even when it is present in adequate amount is very mild. The basic constraint in the availability of P is its solubilization as it gets fixed both in acidic and alkaline soil. Soil fixed P can only be solubilized by phosphate solubilizing microorganisms (PSMs).These bacteria released different types of organic acids in the soil which make P soluble and available to plants. The potential of these PSMs to solubilize P varies and mainly depends upon mechanism adopted for solubilization, their molecular genetics as well as their ability to release P in soil. The PSMs, having all the characteristics of phytohormone production, nitrogen fixation, as well as, heavy metal decontamination and creating salt stress tolerance in plants, are quite rare for sustainable agriculture. Application of this environment friendly approach for increasing crop productivity as well as its impact on soil and plant health is discussed in this review which will not only open new avenues of research but also provide fruitful information about phosphate solubilizing microbes for sustainable agriculture development.

Application of phosphate solubilizing bacteria for improvement of existing pools of phosphate in soil is important for plant growth. From rain fed area of Mansehra, 14 microbes were isolated. Among these, three isolates Bacillus velezensis, Bacillus subtilis, and Bacillus safensis exhibited strong phosphate solubilizing potential, indole acetic acid (IAA) and organic acid production, and antibacterial and antibiotic resistances. Due to better phosphate solublization potential, plant growth-promoting rhizobacteria, B. velezensis was used as bio-inoculant on wheat var. Pir sabaq alone, with rock phosphate (RP) and with 50%, 75%, and 100% single super phosphate (SSP) and urea. Application of RP with B. velezensis increased 50% phosphate and nitrate in soil and 80% in leaves. Plants treated with 100% SSP + urea and B. velezensis showed 50% higher P in soil and 90% in leaves. Application with RP showed significant increases on growth indices of wheat and results were more pronounced in RP + B. velezensis and 100% SSP + urea + B. velezensis treatments. Soluble protein and sugar contents of leaves were 46% and 24% higher in RP + B. velezensis, while IAA and gibberellic acid (GA) were 34% and 54% higher. Highest increases in protein (56%), sugar (30%), IAA (50%), and GA (90%) were found in 100% SSP + urea + B. velezensis. Spike length, seeds per spike, and weight of 1000 seed were 19%, 32%, and 26% higher in RP + B. velezensis, while these increases were 39%, 52%, and 33%, respectively in 100% SSP + urea + B. velezensis treatment. Bio-inoculation of B. velezensis with RP and chemical fertilizer may be helpful for improving productivity of cereal crops and sustainable agriculture.

Marble industry is one of the pillars of modern buildings and structures but marble industry’s effluents, organic pollutants and heavy metals are affecting natural ecosystem. In present work, fourteen bacteria were isolated from the rhizo-surface soil, receiving marble industry effluent from Hattar industrial area. The soil was heavily polluted with manganese (Mn). Among isolated strains Rothia sp, Methylobacterium sp, Pantoea eucrina and Bacillus safensis were found strong phosphate solublizer, indole acetic and organic acids producers. B. safensis and P. eucrina exhibited strong tolerance at 1750 ppm and 2000 ppm of MnSO4; and were applied alone and in consortium to naturally polluted soil collected from Hattar in a green house on maize (Zea mays L.). Consortium + recommended dose of fertilizers (RDF) and different concentrations of MnSO4 improved 12-25% of plant biomass. Plants grown in naturally polluted soil of marble industry exhibited 50-60% increases in growth indices in single inoculation, and these increases were 65% in consortium application. Plants grown in naturally polluted soil exhibited 30-45% increases in physiological indices. It is inferred that Mn stressed soil may be reclaimed by the application of B. safensis and P. eucrina.

The allelopathic potential of Sesamum indicum L. has been studied in relation to Triticum aestivum L. The seeds of wheat were soaked in aqueous extracts of plant parts of S. indicum at 3, 5, and 8% for 24 h. A pot experiment was conducted to determine the effects of sesame on percent germination, root and shoot length, fresh and dry weight, activities of antioxidant enzymes, phytohormones, and nutrient uptake by wheat roots and shoots. A significant decrease was recorded in the percent germination of wheat seeds treated with sesame plant extracts (maximum by leaf extracts) and shoot length (maximum by 8% stem extracts) concomitant with the marked increase in the root length and weight (maximum increase with 8% leaf extract). The activity of superoxide dismutase, peroxidase and ascorbate peroxidase was increased in wheat roots and shoots treated with different concentrations of S. indicum plant parts. The extracts of all parts of S. indicum increased the indole acetic acid (IAA) content in the wheat roots. Abscisic acid (ABA) content was higher in wheat shoots. The maximum increase in micronutrient uptake was observed at 8% leaf extract. It is inferred from the present study that all parts of S. indicum have allelopathic potential with leaves being more potent. S. indicum extract changes root to shoot ratio and modulate IAA and ABA ratio in root and shoot which can be implicated not only in the control of weed germination but also in combating drought stress in recipient plant.