The packing is moisture proof and well tolerates transportation and handling. Liquid formulation is available in one lr HDPE containers and in lr barrels. Description: Azospirillum is an associative type of bacteria, living in close proximity with the root zone. During unfavorable conditions it forms cyst which helps to tide over unfavorable conditions.
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The benefits to plants by inoculation with Azospirillum have been primarily attributed to its capacity to fix atmospheric nitrogen, but also to its capacity to synthesize phytohormones, in particular indoleacetic acid.
Recently, an increasing number of studies has attributed an important role of Azospirillum in conferring to plants tolerance of abiotic and biotic stresses, which may be mediated by phytohormones acting as signaling molecules.
Both mechanisms are related to the NPR1 protein, acting as a co-activator in the induction of defense genes. Azospirillum can also promote plant growth by mechanisms of tolerance of abiotic stresses, named as induced systemic tolerance, mediated by antioxidants, osmotic adjustment, production of phytohormones, and defense strategies such as the expression of pathogenesis-related genes.
The study of the mechanisms triggered by Azospirillum in plants can help in the search for more-sustainable agricultural practices and possibly reveal the use of PGPB as a major strategy to mitigate the effects of biotic and abiotic stresses on agricultural productivity.
Introduction Projections of population increases, especially in developing countries, as well as of life expectancy worldwide, imply greater needs for food and feed FAO To achieve higher productivity, agriculture is being intensified, mainly with monocultures highly dependent on increased chemical inputs, including pesticides and fertilizers McArthur and McCord ; Roser and Ritchie By this definition, rhizobia—studied and used in commercial inoculants for more than a century—are also PGPBs.
Undoubtedly, besides rhizobia, the most studied and used PGPB is Azospirillum, encompassing bacteria with a remarkable capacity to benefit a range of plant species Bashan and de-Bashan ; Hungria et al. The genus Spirillum was first reported by Beijerinck , and decades later reclassified as Azospirillum, because of its ability to fix atmospheric nitrogen N2 , discovered and reported by the group of Dr.
After the discovery that Azospirillum was diazotrophic, several studies evaluated its capacity to fix N2 and to replace N-fertilizers when associated with grasses Okon et al. Beneficial results have been obtained consistently with Azospirillum applied to a variety of crops e. Okon and Labandera-Gonzalez ; Bashan et al. Intriguingly, although the Brazilian research group headed by Dr. Although the most prevalent reported benefit of Azospirillum has been its capacity of fixing N2, an increasing number of studies describes other properties that imply growth-promotion.
One main property of Azospirillum relies on the synthesis of phytohormones and other compounds, including auxins Spaepen and Vanderleyden , cytokinins Tien et al. Phytohormones greatly affect root growth, resulting in improvements in uptake of moisture and nutrients Ardakani and Mafakheri Some Azospirillum strains can solubilize inorganic phosphorus, making it more readily available to the plants and resulting in higher yields Turan et al. There are also reports of Azospirillum helping in the mitigation of abiotic stresses, such as salinity and drought Creus et al.
Azospirillum has also been reported to help in the mitigation of excessive compost and heavy metals Bacilio et al. Another important feature of Azospirillum is related to biological control of plant pathogens Bashan and de-Bashan a , b ; Khan et al. In this review we will give emphasis to the mechanisms of Azospirillum that can improve plant tolerance of biotic and abiotic stresses Fig.
Under normal conditions, ROS are produced via the aerobic metabolism by the interaction between O2 and electrons escaping from the electron transport chain in the chloroplast and mitochondria Halilwell and Gutteridge Oxidative stress is relieved in plants by antioxidant enzymes, such as superoxide dismutase EC 1. In general, ROS detoxification systems vary with plant species, genotypes, and age, as well as with the type and duration of stress Hodges et al.
The genes that encode the detoxification enzymes are found in different compartments of plant cells, varying in number and location, depending on the plant species. APX isoenzymes in superior plants are encoded by a multigenic family Ozyigit et al. Although early studies have focused on plant response to phytopathogens, there are indications that PGPBs may induce plant oxidative stress as an initial defense response, probably because plants perceive these microorganisms as potential threats.
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Azospirillum: características, habitat, metabolismo