The effect of phosphorus (P) deficiency on phosphatases activities in N2-fixing legumes has been widely studied in hydroponic culture. However, the response of acid phosphatase (APase) and phytase in rhizosphere, nodules and seeds of Phaseolus vulgaris to low soil’s P-availability is not yet fully understood. In this study, six genotypes of N2-fixing P. vulgaris were grown under contrasting soil P-availabilities; i.e., low  (4.3 mg P kg−1) and sufficient (16.7 mg P kg−1) in the Haouz region of Morocco. At flowering and maturity stages, plants were harvested and analyzed for their phosphatases activities, growth and P content. Results show that, low P decreased nodulation, growth, P uptake and N accumulation in all the genotypes, but to a greater extent in the sensitive recombinant inbreed line 147. In addition, while seed P content was slightly reduced under low P soil; a higher P was noticed in the Flamingo and Contender large seeded-beans (6.15 to 7.11 mg g−1). In these latter genotypes, high APase and phytase activities in seeds and nodules were associated with a significant decline in rhizosphere’s available P. APase activity was mainly stimulated in nodules, whereas phytase activity was highly induced in seeds (77%). In conclusion, the variations of APase and phytase activities in nodules and seeds depend on genotype and can greatly influence the internal utilization of P, which might result in low P soil tolerance in N2-fixing legumes

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Abiotic constraints such as water deficit reduce cereal production. Plants have different strategies against these stresses to improve plant growth, physiological metabolism and crop production. For example, arbuscular mycorrhiza (AM)—bread wheat association has been shown to improve tolerance to drought stress conditions. The objective of this study was to determine the effect of AM inoculation on plant characteristics, lipid peroxidation, solute accumulation, water deficit saturation, photosynthetic activity, total phenol secretion and enzymatic activities including peroxidise (PO) and polyphenol oxidase (PPO) in two bread wheat cultivars (PAN3497 and SST806) under well-watered and drought-stressed conditions in plants grown under greenhouse conditions, to determine whether AM can enhance drought tolerance in wheat. AM inoculation improved morphological and physiological parameters in plants under stress. The leaf number increased by 35% and 5%, tiller number by 25% and 23%, chlorophyll content by 7% and 10%, accumulation of soluble sugars by 33% and 14%, electrolyte leakage by 26% and 32%, PPO by 44% and 47% and PO by 30% and 37% respectively, in PAN3497 and SST806, respectively. However, drought stress decreased proline content by 20% and 24%, oxidative damage to lipids measured as malondialdehyde by 34% and 60%, and total phenol content by 55% and 40% respectively, in AM treated plants of PAN3497 and SST806. PAN3497 was generally more drought-sensitive than SST806. This study showed that AM can contribute to protect plants against drought stress by alleviating water deficit induced oxidative stress.

The use of phosphate solubilising bacteria as inoculants increases plant phosphorus (P) uptake and thus crop yield. Strains from the genera Rhizobium are among the most powerful phosphate solubilizing microorganisms. In order to study efficiency in P uptake and nitrogen (N 2 ) fixation, forty-two rhizobia strains natively from Tunisian soils were studied in symbiosis with Cicer Downloaded by [UQ Library] at 03:34 13 July 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 aritenium variety i.e Béja1 frequently cultivated in Tunisia. Plants were inoculated separately with these strains under controlled conditions in perlite under tow source of P i.e. solublemonopotassium phosphate (KH 2 PO 4 ) and insoluble P dicalcium phosphate (Ca 2 HPO 4 ). At flowering stage, growth, nodulation, P uptake and N 2 fixation were assessed in all symbiotic combinations.The results showed that the S27 strain efficiently mobilized P into plants as a significant increase of plant P content was observed when soil is supplied with insoluble P (Ca 2 PO 4 ). This was associated with a significant increase of plant biomass, nodule number and N content under insoluble P conditions. Additionally, inoculation with Mesorhizobium strains S27