Influence of arbuscular mycorrhizal fungi and Pseudomonas fluorescens with different levels of superphosphate on the growth response of linseed (Linum usitatissimum L.)

Neetu Neetu1, Ashok Aggarwal1*, Anju Tanwar1, and Alpa Alpa1

The aim of this study was to investigate the influence of arbuscular mycorrhizal fungi (AMF) Glomus mosseae (T.H. Nicolson & Gerd.) Gerd. & Trappe and Acaulospora laevis (Gerd. & Trappe) on linseed (Linum usitatissimum L.) growth response with phosphate solubilizing bacteria Pseudomonas fluorescens; different doses of superphosphate were used: 20 kg ha-1 (half recommended dose), 40 kg ha-1 (recommended dose), and 80 kg ha-1 (double recommended dose) in earthen pots filled with sterilized soil under greenhouse conditions. Among all the growth parameters, the following were the highest in the G. mosseae + P. fluorescens combination at the medium concentration (recommended superphosphate dose): plant height (78.74 ± 1.8 cm), fresh shoot weight (3.45 ± 0.294 g), dry shoot weight (0.57 ± 0.007 g), fresh root weight (0.223 ± 0.023 g), dry root weight (0.036 ± 0.004 g), root length (17.67 ± 0.48 cm), AM spore number (94.4 ± 9.86), shoot (1.14 ± 0.115%) and root (1.29 ± 0.110%) P content, and acidic (0.447 ± 0.012 IU g-1 FW) and alkaline phosphatase activity (0.119 ± 0.008 IU g-1 FW). The percentage mycorrhizal root colonization with the A. laevis + P. fluorescens (86.86 ± 2.17%) combination and chlorophyll content with the G. mosseae + A. laevis + P. fluorescens (0.474 ± 0.009mg g-1 FW) combination recorded the highest values at the low concentration (half recommended superphosphate dose) as compared with non-mycorrhizal plants (control). The high superphosphate dose clearly reduced or decreased all the growth parameters. Therefore, vigorous growth and maximum flax yield can be achieved by inoculating plants with AM fungi and P. fluorescens with the recommended dose or less than the recommended dose of superphosphate.

Keywords: Linum usitatissimum, AM fungi, Pseudomonas fluorescens, P uptake, P activity.
1Kurukshetra University, Department of Botany, Kurukshetra, Haryana, India.*Corresponding author (aggarwal_vibha@rediffmail.com).