The stimulatory effects of L-tryptophan and plant growth promoting rhizobacteria (PGPR) on soil health and physiology of wheat

Abstract

During the present study, Pseudomonas moraviensis and Bacillus cereus, were isolated from rhizosphere soil of halophytic weed (cenchrus ciliaris L.) of Khewra salt range, and used as bioinoculants. The plant growth promoting rhizobacteria (PGPR) were applied to wheat (Triticum aestivum) by seeds soaking, and aqueous solution of tryptophan was added to the rhizosphere soil at 1ug/L, after seed germination. Experiment was conducted at Quaid-e-Azam University Islamabad both in pots (filled with sterilized soil) under axenic condition and in field under natural condition, for two consecutive years. The inoculation of Pseudomonas moraviensis and Bacillus cereus, significantly increased the organic matter, P, K, Ca, and NO 3 -N availability of soil. The inoculation of these PGPR positively enhanced growth and physiology of treated plants, and this affect was further augmented in the presence of tryptophan. Addition of tryptophan with Pseudomonas moraviensis and Bacillus cereus increased the fresh weight, proline contents and activities of antioxidant enzymes significantly over control. Added tryptophan with both PGPR, improved the number of plants at yield and seeds establishment by improving number of seeds/spike and spike length. Effects of PGPR inoculation alone and with tryptophan were more pronounced in pots grown plants. It is inferred from the results, that tryptophan addition is a competent source for increasing potential of PGPR, thereby improving wheat growth, and physiology.

Phosphorus Availability in Wheat, in Volcanic Soils Inoculated with Phosphate-Solubilizing Bacillus thuringiensis

“…after 31 days of the Zadoks scale. Furthermore, Ul Hussan and Bano [36] also reported an increase of available P in the rhizosphere of wheat plants inoculated with Bacillus cereaus. These findings, shown that the increase of P in the rhizosphere can provide a better development of the plants.…”

Isolation of efficient phosphate solubilizing bacteria capable of enhancing tomato plant growth

“…Specifically, soil bacteria from genera Pseudomonas, Bacillus, Rhizobium, and Enterobacter have been thought to be the most powerful P solubilizers (Hassan and Bano, 2015;Whitelaw, 1999). The less studied Pantoea genus contains several phosphate-solubilizing bacteria such as P. agglomeran (Son et al, 2006), P.eucalypti (Castagno et al, 2011), P. ananatis (Oliveira et al, 2009) P. vagans (Rfaki et al, 2014) and Pantoea sp.…”

Salt and alkali stresses reduction in wheat by plant growth promoting haloalkaliphilic bacteria

“…Therefore, their usage as soil amendments in saline and alkaline soils (Butale et al, 2010) was suggested, which was similar to the results of this study. During the study of Pseudomonas moraviensis and Bacillus cereus as PGPR bacteria from rhizosphere soil of halophytic weed (Cenchrus ciliaris L.) of Khewra salt range on soil health and physiology of wheat, it was shown that their inoculation significantly increased organic matter, P, K, Ca, and NO 3 -N availability of soil (Ul Hassan and Bano, 2015). The wheat inoculation of these PGPR positively enhanced growth and physiology of treated plants (Ul Hassan and Bano, 2015).…”