Alternative rooting induction of semi-hardwood olive cuttings by several auxin-producing bacteria for organic agriculture systems

Abstract

Southern Spain is the largest olive oil producer region in the world. In recent years organic agriculture systems have grown exponentially so that new alternative systems to produce organic olive cuttings are needed. Several bacterial isolates, namely Pantoea sp. AG9, Chryseobacterium sp. AG13, Chryseobacterium sp. CT348, Pseudomonas sp. CT364 and Azospirillum brasilense Cd (ATCC 29729), have been used to induce rooting in olive semi-hardwood cuttings of Arbequina, Hojiblanca and Picual cultivars of olive (Olea europea L). The first four strains were previously selected as auxin-producing bacteria and by their ability to promote rooting in model plants. They have been classified on the basis of their 16S rDNA gene sequence. The known auxin producer A. brasilense Cd strain has been used as a reference. The inoculation of olive cuttings was performed in two different ways: (i) by dipping cuttings in a liquid bacterial culture or (ii) by immersing them in a paste made of solid bacterial inoculant and sterile water. Under nursery conditions all of the tested bacterial strains were able to induce the rooting of olive cuttings to a similar or greater extent than the control cuttings treated with indole-3-butyric acid (IBA). The olive cultivars responded differently depending on the bacterial strain and the inoculation method. The strain that consistently gave the best results was Pantoea sp. AG9, the only one of the tested bacterial strains to express the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase. The results are also discussed in terms of potential commercial interest and nursery feasibility performance of these strains.

Application of Halotolerant Bacteria to Restore Plant Growth Under Salt Stress

“…Bacteria containing ACC-deaminase with a potential effect on growth of maize under saline conditions were also isolated and characterized by Hussain et al ( 2013 ). Montero-Calasanz et al ( 2013 ) confi rmed, that the inoculation of Pantoea sp. AG9, Chryseobacterium sp.…”

Rooting response of Prunus domestica L. microshoots in the presence of phytoactive medium supplements

“…In recent years the European Commission imposed restrictions on the use of chemicals, including auxins, in plant production. Therefore, searching for root-promoting substances and exploitation of natural biostimulators is one of strategies aimed at improving the rooting efficiency with a simultaneous reduction of the use of exogenous auxins (Arthur et al 2004;Pacholczak et al 2012a, b;Montero-Calasanz et al 2013). The application of natural products during commercial rooting may also limit the losses caused by poor quality of the root system or of the shoot, caused by auxin used in the rooting treatment (De Klerk et al 1999;Kakani et al 2009).…”

Effect of Bioinoculants on the Quality of Crops

“…Drought tolerance of Macadamias improves when mycorrhized (Yooyongwech et al 2013). Similarly, we could not find any information concerning the effect of PGPR on the quality of O. europaea fruits; actually, the only report concerns the rooting induction of some auxin-producing bacteria on olive cuttings (Montero-Calasanz et al 2013). Olive trees can form arbuscular mycorrhiza (Citernesi et al 1998) although species-specific responses have been reported: three different cultivars of olive plants have been found to be colonized by a Gigaspora species, but only one of the three by a Glomus species (Chatzistathis et al 2013).…”