ACC-deaminase and/or nitrogen-fixing rhizobacteria and growth response of tomato (Lycopersicon pimpinellfoliumMill.)

Abstract

The study aimed to identify and select important plant growth-promoting rhizobacteria (PGPR) and examine the response of tomato growth upon inoculation. Inoculation with rhizobacterial isolates increased all the measured physical, chemical, and enzymatic growth parameters compared to control. However, the TAN1 isolate had the highest effect, and significantly (P < 0.05) increased the root length (8.25-fold), root fresh (8.36-fold) and dry (12.6-fold) weight, shoot length (6.92-fold), shoot fresh (7.18-fold) and dry (6.90-fold) weight, number of leaves (11.0-fold), chlorophyll a (6.25-fold), chlorophyll b (10.7-fold), carotenoid contents (8.80-fold), seedlings fresh (9.0-fold) and dry (8.71-fold) weight, plant macronutrient uptake, i.e. N (7.7-and 8.9-fold), P (10.5-and 11.4-fold), K (7.8-and 8.8-fold), , and Mg (12.6-and 9-fold) in shoot and root, plant micronutrient uptake, i.e. Zn (6.6-, 10.2-), Cu (9.3-, and 10.3-fold), Fe (7.7-and 10.7-fold), and Mn (4.7-and 5.7-fold) in shoot and root and plant antioxidant enzymes, i.e. glutathione S-transferase (10.7-fold), peroxidase (8.1-fold), and catalase (10.5-fold). Our results concluded that inoculation of agricultural crops with rhizobacteria is a very useful approach to increase the plant growth. The rhizobacteria having both 1-aminocyclopropane-1-carboxylate (ACC) deaminase and nitrogen-fixing activity are more effective than rhizobacteria possessing either ACC-deaminase or nitrogen-fixing activity alone for growth promotion of crops.Keywords: PGPR; ACC-deaminase; nitrogen fixation; ethylene and auxin; tomato IntroductionPlant growth-promoting rhizobacteria (PGPR) are free living microorganisms having beneficial effects on plants by colonizing their roots (Ahemad 2012). PGPR promote the plant growth by several direct and indirect ways (Ahemad 2012). Directly, PGPR provide the bacterium-synthesized compounds to the plants, facilitate the nutrient availability and uptake and production of certain phytohormones, e.g. auxin, cytokinins, ethylene, and abscisic acid and giberelins (Ahemad 2012). Indirectly, PGPR minimize or prevent the harmful effects of pathogenic organisms (Ahemad & Malik 2011), moreover, mobilize the nutrients in soils and improve the soil structure (Ahemad & Malik 2011). Inoculation of agricultural crops with PGPR results in multiple positive effects on plant, e.g. increase in the plant growth and vigor, increment in the chlorophyll, protein, proline, and antioxidant enzymes (e.g. peroxidase (POX), catalase, and glutathione reductase) activity that increase the plant immunity (Sahran & Nehra 2011). It has been observed that increased activity of antioxidant enzymes is correlated with resistance, against both biotic and abiotic stresses, in many plant species (Jan et al. 2011).At present, the use of microorganisms with the aim of improving crop production on sustainable basis has increased tremendously in various parts of the world (Glick 2012). This is due to the emerging demand for dependence diminishing of synthetic chemical products, to the grow...

ACC-deaminase and/or nitrogen fixing rhizobacteria and growth of wheat (Triticum Aestivum L.)

“…They are involved in various biotic activities of the soil ecosystem to make it dynamic for nutrient turn over and ultimately sustainable crop production (Ahmed and Kibret, 2014). ACC-deaminase and/or N fixing rhizobacteria & wheat The large active groups of bacteria that inhabiting the rhizosphere benefit the crop plants in several ways, collectively called as plant growth promoting rhizobacteria (PGPR) (Hassan et al, 2014a). Interactions between plants and microorganisms in the rhizosphere can clearly affect growth and development of the crop plants and yield (Hassan et al, 2014a;Ahmed and Kibret, 2014).…”

“…ACC-deaminase and/or N fixing rhizobacteria & wheat The large active groups of bacteria that inhabiting the rhizosphere benefit the crop plants in several ways, collectively called as plant growth promoting rhizobacteria (PGPR) (Hassan et al, 2014a). Interactions between plants and microorganisms in the rhizosphere can clearly affect growth and development of the crop plants and yield (Hassan et al, 2014a;Ahmed and Kibret, 2014). The PGPR can stimulate plant growth indirectly by inhibiting other deleterious microbes, root pathogens, biological control of root crop diseases, by production of antibiotics and siderophores (Ahmed and Kibret, 2014;Hayat et al, 2010).…”

Labile Organic Carbon Fractions, Regulator of CO2 Emission: Effect of Plant Residues and Water Regimes

“…The TOC in the extracts was measured as CO 2 by infrared adsorption after combustion at 760°C using a Shimadzu automatic TOC analyzer (Shimadzu, Japan). MBC was calculated as: where Ct 1 is the extracted carbon (mg kg −1 ) from fumigated samples, Ct 0 is the extracted C (mg kg −1 ) from un‐fumigated samples and 2.22 is the factor, calculated by 0.45, i.e ., 100/45 = 2.22, here 0.45 is the extractable part of microbial C after fumigation .…”

“…where Ct 1 is the extracted carbon (mg kg À1 ) from fumigated samples, Ct 0 is the extracted C (mg kg À1 ) from un-fumigated samples and 2.22 is the factor, calculated by 0.45, i.e., 100/45 ¼ 2.22, here 0.45 is the extractable part of microbial C after fumigation [19].…”

Nitrogen-fixing potential of Halimodendron halodendron (Pall.) Voss in arid and semi-arid areas of Iran

“…The total N content of L. sativum plants was obtained using a modified Kjeldahl method based on 0.5 g of dry plant material [26]. The N content was determined for plants in plastic pots.…”