Effect of Plant Growth Promoting Rhizobacteria on Productivity and Nutrient Use Efficiency of Wheat (Triticum aestivum L.)_Thesis

SUMMARY & CONCLUSION The experiment was carried out on a sandy clay loam soil at “main block 14C” research farm of Indian Agricultural Research Institute, New Delhi 110 012, India during the Rabi season of 2014-2015. The experiment was entitled “Effect of plant growth promoting rhizobacteria on productivity and nutrient use efficiency of wheat (Triticum aestivum L.)”. The objective of the study was to find out the effect of plant growth promoting rhizobacteria (PGPR) on the growth, and productivity of wheat, further to see the effect of PGPR on the NPK uptake and grain quality of wheat and finally to work out the economics of PGPR inoculation in wheat. The experiment was laid out in randomize complete block design with three replications under irrigated condition. The experimental plots received six irrigations and two hand weedings and applied NPK fertilizers based on the treatment combination. The most important findings of the experiment are summarized as bellow. 1. Effect of plan growth promoting rhizobacteria were recorded significant for most of the parameters under study. 2. The combined application of either two or three bacterial or cyanobacterial species were able to fix sufficient atmospheric nitrogen to meet the 25% N requirement of the wheat crop which reduced over the recommended N application, whereas application of single species failed to do so. 3. Application PGPR did not influence the growth parameters viz., plant height, number of tillers m-2 and dry matter accumulation in 30 days after sowing. 4. Combined application 75% N + RPK + Azo + CW1, 75% N + RPK + Azo + PW5, 75% N + RPK + CW1 + PW5, 75% N + RPK + Azo + CW1 + PW5 significantly increased growth parameters viz., plant height, number of tillers m-2 and dry matter accumulation over 75% N + RPK. 5. The highest leaf area were obtained from application of 75% N + RPK + Azo + CW1. 6. Yield attributing characters viz., spike length, spike weight, grain weight per spike, number of grains per spike and test weight were significantly influenced with application of bacterial and cyanobacterial strains. Application of 75% N + RPK + Azo + CW1, 75% N + RPK + Azo + PW5, 75% N + RPK + CW1 + PW5, and 75% N + RPK + Azo + CW1 + PW5 recorded significantly higher values for spike length, spike weight, grain weight per spike, number of grains per spike and test weight treatments over 75% N + RPK whereas they were at par with RNPK treatment. 7. The highest crop growth rate and relative growth rate were obtained from application of 75% N + RPK + Azo + CW1 + PW5. 8. The results showed that 75% N + RPK + Azo + CW1, 75% N + RPK + Azo + PW5, 75% N + RPK + CW1 + PW5, 75% N + RPK + Azo + CW1 + PW5 have recorded significantly higher root length, root volume and root dry weight over all other treatments. However the highest root length 4.08 cm per cm-3 of soil, root volume 6.78 mm-3 per cm-3 of soil and dry weight 0.93 mg per cm-3 of soil were obtained from application of 75% N + RPK + Azo + CW1 + PW5 which were 4%, 30%, and 52% higher from application RNPK respectively. 9. Combined application of bacterial and cyanobacterial inoculants in 75% N + RPK + Azo + CW1, 75% N + RPK + Azo + PW5, 75% N + RPK + CW1 + PW5, 75% N + RPK + Azo + CW1 + PW5 treatments produced significantly higher grain and straw yield over 75% N + RPK but they were at par with RNPK treatment. 10. Highest values of gain yield were obtained from application 75% N + RPK + Azo + CW1 + PW5 which was 77% and 23% higher over absolute control and fertilizer control (75% N + RPK) respectively, whereas application of 75% N + RPK + Azo + PW5 produced highest straw yield which was 35.5% and 13% higher over absolute control and fertilizer control (75% N + RPK) respectively. 11. It was observed that application of 75% N + RPK + Azo + CW1, 75% N + RPK + Azo + PW5, 75% N + RPK + CW1 + PW5, 75% N + RPK + Azo + CW1 + PW5 showed significantly higher values over both RNPK and 75% N + RPK treatments with respect to the soil microbial biomass carbon whereas soil organic carbon was not influenced with application of PGPR. 12. The highest values for dehydrogenase activity and soil chlorophyll were obtained from application of 75% N + RPK + Azo + CW1 + PW5. 13. The highest values for FDA hydrolysis was recorded from application of 75% N + RPK + Azo + PW5. The treatment showed 66% and 33 % higher values over absolute control and 75% N + RPK respectively. 14. The highest gross return (₹ 90,500 ha-1), net return (₹ 62,500 ha-1) and benefit cost ratio (2.17) was obtained from application of 75% N + RPK + Azo + CW1 + PW5. 15. Application of 75% N + RPK + Azo + CW1, 75% N + RPK + Azo + PW5, 75% N + RPK + CW1 + PW5, 75% N + RPK + Azo + CW1 + PW5 treatments showed significantly higher values for N concentration and uptake in grain and straw and protein content in grain over 75% N + RPK, whereas they were at par RNPK treatment 16. The highest P concentration in grain and straw and uptake was recorded in application of 75% N + RPK + Azo + CW1 + PW5. 17. The highest agronomic efficiency was obtained from application of 75% N + RPK + Azo + CW1 + PW5 treatment