Asian Research Thesis Index

Abstract

Intensive use of chemical fertilizers has produced environmental, health and agricultural hazards besides their high cost. Microbial (plant growth promoting rhizobacteria) inoculation as substitute to chemical fertilizers could be an effective way for sustainable sunflower production. Therefore, a field study was performed at the Agronomic Research Area, Department of Agronomy, University of Agriculture, Faisalabad, to evaluate role of plant growth promoting rhizobacteria for improving nitrogen and phosphorus use efficiency in sunflower. The study comprised of two experiments carried out during 2012 and 2013 in randomized complete block design (RCBD) with three replications. In first experiment, sunflower hybrid (Hysun-33) was subjected to eleven treatments viz. Control, Recommended N (100%), 100% N + PGPR (Azospirillum) seed inoculation, 75% N + PGPR (Azospirillum) seed inoculation, 50% N + PGPR (Azospirillum) seed inoculation, 100% N + PGPR (Azotobactor) seed inoculation, 75% N + PGPR (Azotobactor) seed inoculation, 50% N + PGPR (Azotobactor) seed inoculation, 100% N + PGPR (Azospirillum + Azotobactor) seed inoculation, 75% N + PGPR (Azospirillum + Azotobactor) seed inoculation, 50% N + PGPR (Azospirillum + Azotobactor) seed inoculation. While second experiment comprised of treatments: Control, Recommended P (100%), 100% P + PGPR (Bacillus) seed inoculation, 75% P + PGPR (Bacillus) seed inoculation, 50% P + PGPR (Bacillus) seed inoculation, 100% P + PGPR (Pseudomonas) seed inoculation, 75% P + PGPR (Pseudomonas) seed inoculation, 50% P + PGPR (Pseudomonas) seed inoculation, 100% P + PGPR (Bacillus + Pseudomonas) seed inoculation, 75% P + PGPR (Bacillus + Pseudomonas) seed inoculation, 50% P + PGPR (Bacillus + Pseudomonas) seed inoculation. The results of first experiment depicted that both inoculants and their mixture with different nitrogen rates showed an increase in growth, yield, quality and nutrients uptake parameters. The results further revealed that 100% nitrogen + PGPR (Azospirillum + Azotobactor) inoculation not only produced highest achene and oil yields but also gave maximum gross and net income and benefit cost ratio during both years (2011 and 2012) of experimentation. However, 75% nitrogen + PGPR (Azospirillum + Azotobactor) inoculation produced statistically same yield as with recommended nitrogen (100%). The results of the second experiment showed significant improvement in growth, yield, quality and nutrients uptake of sunflower crop by both inoculation and their mixture sources with various combinations of phosphorus. However, maximum achene and oil yields with highest gross, net income and benefit cost ratio were obtained with the combination of 100% phosphorus + PGPR (Bacillus + Pseudomonas) inoculation during both years. But applying the combination of 50% phosphorus + PGPR (Bacillus + Pseudomonas) inoculation achieved the achene and oil yield statistically comparable to that of recommended phosphorus (100%) without inoculation. The study suggested that 25% of nitrogen and 50% of phosphorus fertilizer doses can be reduced by applying PGPR (Azospirillum + Azotobactor) and (Bacillus + Pseudomonas) inoculation sources respectively, for achieving sunflower achene yield which was obtained by using 100% nitrogen and phosphorus fertilizers without inoculation.

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