Radha PraannaASHA BHARTI2020-06-202020-06-202019http://krishikosh.egranth.ac.in/handle/1/5810147804T-10278The agronomic benefits of cyanobacterial biofertilizers for rice as nitrogen supplements are well established, as also their ability to colonise diverse aquatic, terrestrial and aerial habitats. Keeping in view their eco-physiological adaptive traits, their use as amendments to rooting mixes for Chrysanthemum was explored. Chrysanthemum requires surplus amounts of chemical fertilizers, particularly nitrogen (N) at vegetative stage and is propagated through stem cuttings, grown mainly in soil-less media. The present investigation was undertaken to optimize the amendment of Anabaena torulosa, Anabaena doliolum or Anabaena laxa, in two commonly employed rooting mixes- sand and a combination of cocopeat, vermiculite and perlite in 3:1:1 ratio. The extended long term priming effect of the cyanobacterial amendment was evaluated at various stages of crop growth, development and flowering. Preliminary analyses of the growth and colonisation behaviour of the three cyanobacterial strains in horticultural substrates- rooting mix and sand illustrated significant improvement in physicochemical properties and nutrient status of the medium. Cyanobacterial amendment resulted in 30-40 % increment in the availability of nitrogen as well as micronutrients. The root proliferation and colonisation ability of cyanobacterial strains individually for both the Chrysanthemum varieties, Pusa Aditya and Jaya at nursery stage, was confirmed in hydroponics co-cultivation experiment conducted using BG11 medium. Nurseries of both varieties showed significantly higher indole acetic acid production and root biofilm formation. Cyanobacterium amended rooting mixes were then used for raising nurseries of Pusa Aditya and Jaya, along with unamended controls. Rooting mix proved to be a better substrate than sand, for facilitating substantial rooting of both varieties and significantly enhancing the concentrations of carbohydrates. The nursery plantlets exhibited prolific rooting pattern and overall better performance in terms of biochemical and biometric attributes, with Anabaena torulosa and Anabaena laxa performing the best in Pusa Aditya and Jaya respectively in rooting mix after 30 days. Principal Component Analyses showed the distinct and significant effects of the 148 tripartite interactions of cyanobacteria, potting media and cuttings and positive correlation of nutrient attributes with plant parameters. The cyanobacterium-primed nurseries after transplanting in pots, with two different doses of nitrogenous fertilizer (full and 75 %) and full doses of P and K fertilizers, exhibited a significant increase in microbial biomass carbon and nitrogen availability in soil and increases in PLFA content over control, particularly with 75 % dose of urea. Significant improvement in the quality traits of flowers such as early appearance of buds, flower fresh weight, size, pigments and sugar content in cyanobacteria primed plants of both varieties were recorded. Positive correlation was observed in both varieties between soil microbiological properties and biochemical/biometric growth attributes of plant. This comprehensive study illustrated the promise of cyanobacterial amendment, as a priming option, which can provide more than 25 % N savings, besides reducing agrochemical use in propagating Chrysanthemum nurseries. Additionally, long-term effects of cyanobacterium-mediated priming of nursery to flowering, with distinct enhancement in soil biological properties, plant growth and flower quality traits further highlights the promise of such options as environment- friendly interventions. Keywords: Chrysanthemum; Pusa Aditya; Jaya; Amendment; Cyanobacteria; Nurseryen-USnullThesis