100 Efect of organic manures, PGPR and micronutrients on yield and quality enhancement in ajwain (Trachyspermum ammi L) G S Thanuja 1 *, B Srinivasulu 1 , K M Yuvaraj 1 & K Giridhar 2 1 College of Horticulture, Dr YSR Horticultural University, Anantharajupeta-516 105, Kadapa, Andhra Pradesh. 2 AICRP on Spices, Dr. YSRHU, Lam, Guntur, Andhra Pradesh. *E-mail: th_09@redifmail.com Received 05 November 2020; Revised 14 May 2021; Accepted 17 May 2021 Abstract Experiments were conducted for two consecutive years during 2017-19 to study the efect of organic manures, PGPR and micronutrients on yield and quality of ajwain seed. Farm yard manure (FYM) and vermicompost (VC) were used as organic sources at 50% and 75% recommended dose of nitrogen (RDN) as basal dose. PGPRs namely Azospirillum lipoferum, Bacillus megaterium and Frateuria aurantia were used for seed priming. Micronutrients namely ZnSO 4 and Fe 2 SO 4 were applied thrice as foliar application @ 0.5% frst before fowering, second at 50% fowering and third during grain formation. The results revealed that highest number of umbels plant -1 , umbellets umbel -1 , number of fruits umbellet -1 , seed yield plant -1 , seed yield hectare -1 , straw yield, biological yield, test weight of seeds and essential oil yield were recorded with the application of 50% RDN through VC, which was on par with 50% RDN through FYM, seed priming with Azospirillum and foliar application of zinc with respect to their individual efect. Maximum essential oil content, fxed oil content and thymol content were also observed in case of application of 50% RDN through VC, seed priming with Azospirillum and foliar application of zinc individually. Highest Beneft Cost Ratio (BCR) of 3.33 was recorded with combined application of 50% of RDN through FYM along with seed priming with Azospirillum and foliar spray of Zn at 0.5%. Keywords: Azospirillum lipoferum, Bacillus megaterium, Frateuria aurantia, thymol Introduction Ajwain is an aromatic seed spice, cultivated mainly for its seed, herb and volatile oil. Seed possesses stimulant, antispasmodic and carminative properties and used traditionally as an important remedial agent for fatulence, abdominal tumors, diarrhoea and bronchial problems etc. Usually, thymol is the main essential oil constituent and its yield varies from 35% to 60% (Sega & Kitajima 2001; Zarshenas et al. 2014). Being a cash crop, ajwain is geting importance among the farmers of Rayalaseema region of Andhra Pradesh, as against the traditional crop, as farmers are interested in diversification of cropping pattern through Journal of Spices and Aromatic Crops Vol. 30 (1) : 100-106 (2021) Indian Society for Spices doi : 10.25081/josac.2021.v30.i1.6576