Oroxylum indicum is a medicinally important forest tree species. This species is categorized as vulnerable as well as endangered in different parts of India due to over exploitation of whole plant for medicinal uses. Therefore, its conservation is must and on this aspect an experiment was performed to see the effect of bioinoculation on the plastochron interval and root surface area in the seedlings of O.indicum. The seedlings of O. indicum were inoculated with plant growth
promoting microbes (PGPMs) both alone and consortium. The Plastochrone Interval of the seedlings of O. indicum was studied after first, second and third inoculation (i.e. 90, 180 and 270 DAI). While the root surface area was calculated after the completion of final stage of inoculation. After first stage of inoculation it was found that the first to second leaf primordium was initiated in control treatment after long interval of 43 days and it ceased after 83 days (2 leaf
primordium). But in case of seedlings treated with mixed consortium of bacteria,fungus and mycorrhiza, the 1-2 leaf primordium appeared after 21 days and ceased after 102 days. Plastochron interval of O. indicum after second stage of
inoculation showed that the leaf primordia appeared after 33 days in control treatment whereas in seedlings treated with bacteria and mycorrhiza it appeared after 20 days respectively. The leaf primordial appearance ceased to appear after 61 days in case of control treatment, but in seedlings treated with mixed consortium, the leaf primordial appearance continued to appear.Plastochrone
interval index of O. indicum after third stage of inoculation showed that the 1-2 leaf primordium initiated after 49 days and ceased later in control treatment. The leaf primordia showed wilting and symptoms under stress and the initiation of
leaf primordia completely ceased after third stage of inoculation. Whereas, the initiation of leaf primordia didn’t ceased in rest treatments. 1-2 leaf primordium initiated after 13 days in seedlings treated with mixed consortium of bacteria, fungus and mycorrhiza. 8-9 leaf primordium initiated after 17 days in seedlings treated with mixed consortium. The root surface area of the seedlings of O.indicum was calculated and it was found that the root surface area (cm) was
maximum (140.88±5.18) in seedlings treated with mixed consortium of bacteria,fungus and mycorrhiza and it was minimum (47.509±1.66) in Control.
Keywords: Oroxylum indicum, plastochron interval, root surface area, bioinoculation, mycorrhiza