Effects of plant growth promoting rhizobacteria (PGPR) on Citrus macrophylla rootstock

Citrus is one of the largest fruit crops grown in Morocco. Citrus crops gain in importance due to the jobs generated during the production process of fresh or processed fruit. Intensive agriculture is characterized by the excessive use of inorganic fertilizers and pesticides. This production system has generated serious environmental contamination problems, thus, it is necessary to implement sustainable production strategies to reduce the use of synthetic chemicals and contribute to soil and water conservation. In this context, Seventy two Rhizobacterial isolates of fluorescent Pseudomonas were isolated from rhizosphere soil of Citrus in the Sapiama nursery. These isolates were tested on germination and growth of Citrus macrophylla rootstock. The results obtained showed that the isolate C11 significantly stimulated germination 16 days after seed inoculation. The C26, C6 and C24 isolates showed PGPR effects improving significantly the growth parameters of C. macrophylla rootstock. They significantly promoted plant height, collar diameter and root length. This study concluded that the Pseudomonas isolates could be potential alternative biofertilizers to chemical products and could be considered as a promising main component for sustainable agriculture development strategy in Citrus farming. Keywords: Citrus macrophylla, Pseudomonas, PGP

Isotherms and kinetic study of dihydrogen and hydrogen phosphate ions (H2_{2}PO4−_{4}^- and HPO42−_{4}^{2-}) adsorption onto crushed plant matter of the semi-arid zones of Morocco: Asphodelus microcarpus, Asparagus albus and Senecio anthophorbium

In the present work H$_{2}$PO$_4^-$ and HPO$_4^{2-}$ ions adsorption onto organic matter (OM) obtained from ground dried three plants growing in arid zones of Morocco has been studied. The adsorption process is affected by various parameters such as contact time, particle size and initial concentration of phosphate solution (C$_{\rm i}$ $\le$ 30 mg/l). The uptake of both ions is increased by increasing the concentration of them selves. The retention of phosphate ions by Asphodelus microcarpus, Asparagus albus are well defined by several isotherms such as the Langmuir, Temkin and Freundlich