Influence on yield and quality of fennel (Foeniculum vulgare Mill.) grown under semi-arid saline soil, due to application of native phosphate solubilizing rhizobacterial isolates

• Due to economic importance as a cash crop, fennel (Foeniculum vulgare Mill.) is cultivated over large areas in many districts of Gujarat, Rajasthan and other states of India.
• Field experiments were conducted for two consecutive years to assess the efficacy of native phosphate solubilizing bacterial (PSB) isolates on growth and yield attributes of fennel crop cultivated in arid and semi-arid conditions prevailing in western India.
• The highest seed yield (2148.66 kg ha-1) was recorded with Bacillus subtilis NRCSS-II (PSB-36) and the lowest seed yield (1744.35 kg ha-1) was observed with Bacillus sp. PS-1 (PSB-20) which was at par with control.
• Application of the PSB isolates resulted into increased essential oil yield as compared to control but Bacillus subtilis NRCSS-II (PSB-36) resulted into enhanced seed yield and essential oil both.
• Biochemical assay of the post harvest soil samples revealed that organic carbon, N, P, K, and EC increased to 0.59%, 78.25 kg ha-1, 28.54 kg ha-1, 178.3 kg ha-1 and 0.99 dS m-1 as compared to control. On the other hand soil reaction (pH) declined to 7.25 as compared to control.

Phosphate solubilizing microorganisms play an important role in balancing plant nutrition through enhanced availability of phosphorus (P) to roots. These microbial strains convert the insoluble phosphates into soluble forms. Phosphate solubilizing bacteria (PSB) were isolated from the saline soil of fennel (Foeniculum vulgare Mill.) cultivation fields under semi- arid climate of Rajasthan, India. Nine native PSB isolates were applied to study their influence on fennel seed yield and essential oil content. Significant effect of different PSB isolates on seed yield of fennel crop was recorded. The highest seed yield (2148.66 kg ha-1) was recorded with Bacillus subtilis NRCSS-II (PSB-36) and the lowest seed yield (1744.35 kg ha−1) was observed with Bacillus sp. PS-1 (PSB-20) which was at par with control. The highest essential oil content was recorded with Bacillus sp.Fen-17 (PSB-26) (2.80%) as compared to control (2.09%). Though application of all the PSB isolates resulted into increased essential oil yield as compared to control but Bacillus subtilis NRCSS-II (PSB-36) resulted into enhanced seed yield and essential oil both. Biochemical assay of the post harvest soil samples revealed that applied PSB isolates caused significant effect on various soil parameters as compared to control. The organic carbon, N, P, K, and EC increased to 0.59%, 78.25 kg ha−1, 28.54 kg ha−1, 178.3 kg ha−1 and 0.99 dS m−1 as compared to control. On the other hand soil reaction (pH) declined to 7.25 as compared to control.