Title of Thesis

Potential of Rhizobia and free living Rhizobacteria containing acc-deaminase for Improving Nodulation and Yield of Chickpea (Cicer arietinum L.) .

Author(s)
SHER MUHAMMAD SHAHZAD 

Abstract
 

There is a beneficial association (symbiotic) between rhizobia and leguminous plants, which consequences in the development of nodules (N-fixing sites in plant roots) on the roots of legumes. Besides to other features, Phytohormones have an imperative function for increasing number of nodules. Some free living rhizobacteria containing 1-aminocyclopropane-1-carboxylate deaminase (ACCD) enzyme activity promotes nodulation in plant by regulating endogenous biosynthesis ethylene in roots. Thus, co-inoculation of rhizobia and rhizobacteria containing ACC-deaminase were evaluated along with P-enriched compost to improve nodulation and yield of chickpea. A series of studies were conducted under axenic, pot (wire house) and natural conditions to evaluate the effectiveness of co-inoculation plus enriched compost on nodulation in chickpea. A number of isolates of free living rhizobacteria and rhizobia were isolated from soil and nodules samples of chickpea plants by using minimal salt medium with ACC as sole source of nitrogen and Yeast Extract Mannitol (YEM) medium respectively. The isolated rhizobacteria were screened for their ability. The collected rhizobial strains were screen for their ability to cause nodulation and PGPR strains for their growth promoting activity under gnotobiotic conditions. All possible combinations of the selected rhizobial and PGPR isolates were tested under gnotobiotic conditions for improving nodulation to screen the best combinations. The role of the selected combinations and rhizobial and PGPR strains included in the combinations, was evaluated for improving nodulation and growth of chickpea through co-inoculation in pot and field trials. The selected rhizobial as well as plant growth promoting rhizobacterial strains containing ACC-deaminase were characterized for plant growth promoting attributes. It was observed that inoculation with rhizobia or PGPR containing ACC-deaminase alone improved nodulation/growth of chickpea over control under natural conditions. Moreover, co-inoculation with rhizobia and ACC-deaminase containing plant growth promoting rhizobacteria further improved nodulation and growth of chickpea as compared to single-strain-inoculation. In a classical triple response study, it was also observed that the selected PGPR containing ACC-deaminase diluted the effects of exogenously applied ACC.

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2.1 Chickpea

2.2 Causes of low yield of chickpea in Pakistan

2.3 Ethylene biosynthesis and plant growth

2.4 Plant growth promoting rhizobacteria

2.5 Rhizobia

2.6 Co-inoculation with rhizobia and plant growth promoting bacteria containing ACC-deaminase

2.7 Composted organic material and biological activity.

3.1 Isolation of Rhizobacteria containing ACC-deaminase and Rhizobia

3.2 Testing ability of Rhizobacteria to use ACC as sole source of Nitrogen

3.3 Screening Rhizobacteria and Rhizobia for their abilities to promote Growth and Nodulation of Chickpea

3.4 Screening Effective isolates of Rhizobacteria and Rhizobia for co-inoculation (Jar and Pouch experiments)

3.5 Effect of single and co-inoculation on growth, yield and Nodulation of Chickpea under Natural conditions

3.6 Characterization of Rhizobacterial Isolates for ACC-deaminase activity

3.7 Classical Triple response Bioassay

3.8 Characterization of Rhizobacteria and Rhizobia for other Traits

3.9 Identification of selected Isolates

3.10 Soil Analyses

3.11 Plant Analysis

3.12 Statistical Analysis

4.1 Effect of rhizobacterial isolates on growth of chickpea seedlings (Screening trials)

4.2 Effect of rhizobial isolates on growth and nodulation of chickpea under axenic conditions (Jar experiment)

4.3 Growth pouch experiment

4.4 Screening of effective isolates rhizobia and rhizobacteria for co-inoculation of chickpea

4.5 Effect of inoculation and co-inoculation on nodulation, growth and yield of chickpea under natural conditions

4.6 Pot experiment-II (2^{nd year)}

4.7 Field Trials

4.8 Classical “triple” response

4.9 Identification and characterization of rhizobacteria and rhizobial isolates

5.1 Screening rhizobacteria and rhizobia for their potential to promote growth and nodulation of chickpea under

      axenic conditions

5.2 Effect of inoculation and co-inoculation on chickpea under natural conditions

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