Plant growth-promoting traits of phosphate solubilizing bacteria isolated from Hippophae rhamnoides L. (Sea-buckthorn) growing in cold desert Trans-Himalayan Lahul and Spiti regions of India

One hundred and six P-solubilizing bacteria (PSB) from rhizosphere soil (RS) and root endosphere (ER) of Hippophae rhamnoides L.(Sea-buckthorn) of two locations viz. Lahaul and Spiti of Himachal Pradesh were isolated using culture-dependent procedures and were screened for various plant growth-promoting traits (PGPTs). Indole acetic acid produced was detected in 76.41 % isolates, siderophore synthesis in 43.39 % isolates and hydrogen cyanide in 19.4 % isolates. The percent growth inhibition against Fusarium oxysporum and Alternaria sp. was detected in 25.5 and 47.2 % isolates, respectively. Overall, 23.56 % of PSB isolates from RS and 16.85 % from ER showed none of the PGPTs tested. Among the PSB showing PGPTs, 36.58 % had single trait and 43.08 % had multiple traits showing two (29.68 %) and three (13.82 %) types of PGPTs. The Shannon–Weaver diversity index revealed that the proportion of PSB isolates possessing PGPTs was higher for RS than for the ER. Furthermore, the five best performing PSBs under in vitro conditions were selected for pot experiment to evaluate their efficiency for growth promotion of tomato seedlings under net house conditions. Among five isolates, Bacillus subtilis CKS1 exhibited significant increase in shoot length (13.82 %), root length (25.07 %), shoot dry weight (29.47 %) and root dry weight (33.33 %). Plant growth-promoting and antifungal activities of Bacillus subtilis CKS1 depict that it may be utilized as a potential biofertilizer for tomato.