Response of Two Canola Genotypes to Plant Growth Promoter Bacteria (Azospirillum spp.): Seed Yield and Its Components, Dry Matter and Harvest Index

To study the effect of plant growth promoter bacteria (PGPB) (Azospirillum spp.) on yield and yield components, dry matter and harvest index of two canola (Brassica napus L.) genotypes, an experiment was conducted at Agricultural Research Station of Gorgan during 2009–10 growing season. The experiment was arranged as factorial in randomized complete block design with three replications. Eight fertilizer treatments (1- Control, without fertilizer and bacteria, 2- Fertilizer recommendation with soil test, 3- 50% of fertilizer recommendation, 4- AZ1 bacterium, 5- AZ10 bacterium, 6- 50% fertilizer recommendation + AZ1 bacterium, 7- 50% fertilizer recommendation + AZ10 bacterium, and 8- 50% fertilizer recommendation + AZ1 and AZ10 bacteria), and 2 canola genotypes (Hyola401 and L6) were included in factorial arrangement. Results showed that the effect of fertilizer treatments was not significant on pod number plant-1 and seed number pod-1, However, it was significant on seed number m-2, 1000-seed weight, seed yield, aboveground dry matter at physiological maturity and havest index. The application of bacteria had a positive role to increase 1000-seed weight of canola genotypes. Fertilizer recommendation with soil test treatment had the highest seed yield (2892 kg ha-1). There was no significant difference between fertilizer recommendation with soil test and 50% fertilizer recommendation + AZ1 bacterium, and 50% fertilizer recommendation + AZ1 and AZ10 bacteria which showed the positive effect of AZ1 bacteria on seed yield of canola. Fertilizer recommendation with soil test had the highest aboveground dry matter at physiological maturity (9140 kg ha-1). On the other hand 50% fertilizer recommendation + AZ1 bacterium had the highest harvest index (31.9%). Seed yield and harvest index of L6 was significantly higher than Hyola401. The mean seed yield of Hyola401 hybrid and L6 was 2258 and 2504 kg ha-1, respectively. The results of this study showed that AZ1 bacterium had positive effect on increasing canola seed yield.