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Peach
Published in Debashis Mandal, Ursula Wermund, Lop Phavaphutanon, Regina Cronje, Temperate Fruits, 2021
Monika Gupta, Rachna Arora, Debashis Mandal
In peaches, T-budding is the most commonly used method for scion propagation. T-budding should be done in autumn months when the mother trees are in a dormant condition. In the Northern Hemisphere, spring budding as well as June budding can also be performed successfully. The buds should be taken from virus free mother plants. Care should be taken to choose the buds that are situated in the central part of the shoot due to their better shape. The budding height should be 10–15 cm from the ground level. In spring, the scion should be shortened above the graft union immediately before bud break. These budded plants should be kept in nursery when they attain a height of 1.2 to 1.4 m. June budding should be preferred in areas with mild spring. The plants attain 60–80 cm height by October and will become ready for sale within a single year. Besides this, peach can also be propagated through air layering (Castro and Silveira, 2003) and herbaceous, semihardwood cuttings, or woody cuttings of scion peach tree cultivars (Mindello et al., 2008). Hardwood cuttings may be treated with indole-3-butyric acid (IBA) as root promoting hormone (Dutra et al., 2002). The stenting technique, that is, simultaneous grafting of the rooted cuttings may be used for the rapid multiplication of peach, but the success rate is very low. However, there is advancement in breeding practices for peach scion and rootstocks with the application of micropropagation (Gomez et al., 2005). Peach rootstocks are generally propagated sexually by using the seeds after breaking the seed dormancy by removing the seed test and GA3 application. Axillary buds taken from healthy shoots (Felek et al., 2017) are used as explants for the in vitro propagation of peach cv. Garnem.6-Benzyladeninepourine, with IBA and gibberellic acid may be used for shoot initiation and shoot proliferation. IBA is the preferable auxin used for in vitro rooting of the peach rootstock GF 677 (Ahmad et al., 2004).
Isolation of bacteria with plant growth-promoting properties from microalgae-bacterial flocs produced in high-rate oxidation ponds
Published in Environmental Technology, 2023
Wiya L. Masudi, Yinka Titilawo, Taobat A. Keshinro, A. Keith Cowan
It has been reported that all bacteria produce IAA and that treatment of mung bean cuttings with PGP bacteria enhances adventitious root formation [81]. Thus, for mung bean hypocotyls, it is purported that bacterial production of auxin in parallel with the secretion of 1-aminocyclopropane-1-carboxylate (ACC) deaminase, plant-derived ethylene [82,83], formation of root-produced galactoglucomannan-oligosaccharides [84], H2O2 [70] and salicylic acid [85] act in concert as signalling agents to initiate and drive adventitious root formation. Indeed, the recent observations employing Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway-enrichment show convincingly that phytohormone signal transduction; phenylalanine, pentose, and glucuronate metabolism; photosynthesis; and biosynthesis of phenylpropanoids, sesquiterpenes, triterpenes, and flavonoids are among the pathways most highly regulated in mung bean hypocotyls by the auxin, indole-3-butyric acid [86].
Drivers to improve metal(loid) phytoextraction with a focus on microbial degradation of dissolved organic matter in soils
Published in International Journal of Phytoremediation, 2023
Justine Garraud, Hélène Plihon, Hervé Capiaux, Cécile Le Guern, Michel Mench, Thierry Lebeau
Another way is to use bacteria able to enhance plant biomass. The bioaugmentation of soils with Plant Growth Promoting Rhizobacteria (PGPR) reduces ethylene stress, due to metal(loid) excess inducing phytotoxicity, through the production of 1-aminocyclopropane-1-carboxylic acid (ACC)-deaminase by the bacteria, which limits the production of the ethylene precursor ACC. Because plant antioxidant system is severely altered by environmental stress, PGPR strains can protect host plant from Reactive Oxygen Species (ROS), which induce oxidative damage, by the production of various enzymatic and non-enzymatic antioxidants (e.g., glutathione reductase activity, superoxide dismutase and catalase). PGPRs also act directly on biomass through the production of growth hormones of the auxin family, notably Indole-3-acetic acid (IAA), which is involved in root growth (especially stimulation and proliferation of lateral roots), but also in the reduction of salt stress and interaction with plant pathogens. Other auxin hormones are also produced such as Indole-3-butyric acid (used on various crops to stimulate flower development and fruit growth, as well as accelerate root formation), and phenylacetic acid (less effect than IAA). Cytokines are the major phytohormone after auxins, which are involved in plant physiological processes including cell growth and differentiation, shoot initiation, inhibit root elongation, and regulate root meristem activity via modulation of the polar auxin transport. Microbial gibberellins are a large group of phytohormones, which stimulate shoot growth (by cell elongation, division and differentiation) and inhibit root growth through the actions of the gibberellin signaling system. Apart from gibberellins, PGPR strains produced various phytohormones and organic compounds such as polyamines, brassinosteroids, jasmonates, salicylic acid, strigolactones, and abscisic acid, which is a key player in plant growth promotion, metal(loid) tolerance, and metabolic process. Finally, PGPRs increase iron uptake by the roots through its mobilization by siderophore produced by specific bacteria as well as phosphate solubilization.
Characterization of plant growth promoting feature of a neutromesophilic, facultatively chemolithoautotrophic, sulphur oxidizing bacterium Delftia sp. strain SR4 isolated from coal mine spoil
Published in International Journal of Phytoremediation, 2019
Sulphur-oxidizing PGPR have been shown to promote uptake of sulfur and thus promote plant health (Grayston and Germida 1991; Banerjee and Yesmin 2004; Anandham et al. 2014). Elemental sulfur present or added in soil is oxidized to sulfate through generation of intermediates like thiosulfate, tetrathionate, trithionate, sulfite, and finally sulfate. Elemental sulfur present in soil must be oxidized to sulfate to be available for plant uptake and nutrition through the following pathway: Elemental sulfur (S0)→thiosulfate (S2O32−)→tetrathionate (S4O62−)→trithionate(S3O62−)→sulfite (SO32−)→sulfate (SO42−). This oxidation process is mainly carried out by S oxidizers that utilize ES or thiosulfate or both as their substrate. The Delftia sp. strain SR4 isolated from sulfur rich habitat of coal mine spoil, utilized both forms of ES and thiosulfate for growth and converted sulfur to plant available form of sulfate. Upon preliminary investigation, this strain showed plant growth promoting characters in plate-based assays and so it was subjected to in-depth investigation on plant growth promotion. Like other rhizobacteria, this plant growth promoting bacteria was not isolated from plant root association. Hence, the spoil sample from where isolation was performed was sparsely populated by some grass species like Saccharum spontaneum, Typha latifolia, etc. Therefire, it may have come in the free spoil sample from the rhizosphere zone. Plant growth and development are dependent on the level of hormones and nutrients, where PGPR do have a substantial influence (Asari et al. 2017). PGPR colonize plant roots and promote plant health directly by supplying nutrients and phytohormones or indirectly by inducing plant defense system (Ahmad et al. 2008). PGPR support nutrient uptake, e.g. solubilize phosphorous and iron, produce auxins, which include indole-3-acetic acid (IAA) and indole-3-butyric acid that can support plant growth. Most PGPRs secrete IAA that plays a very important role in rhizobacteria plant interactions. IAA affects plant cell division, cell differentiation, germination, increases shoot and root development, suppresses plant phytopathogen, and many others. Many PGPRs produce siderophores (low-molecular mass iron chelators) that help bacteria acquire iron and host plants assimilate this iron from bacterial siderophores by various mechanisms (Asari et al. 2017). Delftia sp. strain SR4 isolated as sulfur-oxidizing autotrophic soil bacterium showed plant growth promoting traits like production of indole-3-acetic acid (phytohormone that increases the plant root surface area for absorption of nutrients), ammonia (improves plant bacteria interaction), HCN (acts against root pathogens and induce systemic resistance) and siderophores (capture and solubilize iron). Field verification of the strain with pot assay in enhancing growth and sulfur metabolism of B. juncea confirmed its role as plant growth promoting bacteria.