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Forty-four soybean genotypes with different photoperiod response were selected after screening of 1000 soybean accessions under artificial condition and were profiled using 40 SSR and 5 AFLP primer pairs. The average polymorphism information content (PIC) for SSR and AFLP marker systems was 0.507 and 0.120, respectively. Clustering of genotypes was done using UPGMA method for SSR and AFLP and correlation was 0.337 and 0.504, respectively. Mantel's correlation coefficients between Jaccard's similarity coefficient and the cophenetic values were fairly high in both the marker systems (SSR = 0.924; AFLP = 0.958) indicating very good fit for the clustering pattern. UPGMA based cluster analysis classified soybean genotypes into four major groups with fairly moderate bootstrap support. These major clusters corresponded with the photoperiod response and place of origin. The results indicate that the photoperiod insensitive genotypes, 11/2/1939 (EC 325097) and MACS 330 would be better choice for broadening the genetic base of soybean for this trait.

The arbuscular mycorrhizal (AM) fungi-rhizobia synergism is a promising approach for improving the growth and nutrition of soybean. It is, therefore, imperative to evaluate potential soybean rhizobia and AM fungi singly to identify their stress protectant physiological traits, enhance growth and nodulation of soybean and improve soil health. The efficacy of five root nodulating soybean rhizobia and an indigenous AM fungus, Glomus intraradices, was evaluated on soybean (cv JS 93-05) under microcosm conditions. In general, all the inoculated plants showed higher fresh shoot and root weight, and nodule number as compared to uninoculated control plants. The plants inoculated with Bradyrhizobium japonicum (strain USDA 110), B. liaoningense 17c (MTCC 10753) and AM fungus showed higher growth and nodulation. However, the plants inoculated with rhizobia 12c (unidentified), B. japonicum DE2-5a (MTCC 10751) and USDA 205 did enhance nodulation but found at par with the other inoculated plants. Interestingly, these inoculated plants found to have comparatively higher nitrogen and phosphorus uptake. B. japonicum (strain USDA 110), native slow growing rhizobia isolate DE2-5a and AM fungi were also found to stimulate proline content in shoots, and trehalase and fluorescein diacetate activities in the rhizosphere soil. Considering the growth and physiological responses of AM fungi and rhizobial strains (DE2-5a and 17c) to soybean, there is a need for further testing the synergistic responses to evolve better survival candidates under drought-stress conditions.

Seed coat permeability and electrolyte leaching are the important traits that have been negatively associated with seed longevity in soybean. The objective of this study was to use SSR markers to identify genomic regions significantly associated with QTLs controlling seed coat permeability and electrolyte leaching in a segregating F 2 population derived from a cross of Birsa soya-1 x JS 71-05. Parental polymorphism survey using 145 SSR markers identified 21 polymorphic ones, which were used to genotype 153 F 2 individuals. Four independent markers (Satt434, Satt538, Satt281 and Satt598) were significantly (P=0.05) associated with seed coat permeability. One of these markers (Satt 281) also showed significant association with electrolyte leaching that partly supported the observed positive correlation (r = 0.425) between the two traits. Markers for seed coat permeability individually explained 3.9% to 4.5% of the total phenotypic variation, while the marker linked with electrolyte leaching explained 5