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  • Author or Editor: Jerzy Nowak x
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Placental and ovular tissues of a diploid clone of potato (Solanum tuberosum L.) were analyzed for their respective free polyamine content at different stages of postpollination gynoecial development. In the placentae, putrescine, spermidine, and spermine concentrations decrease as the placental tissues proliferate during pulp formation. Although there is a decrease in total free polyamine concentration in the ovules as cellular endosperm develops, putrescine and spermidine levels increase before the latter stages of embryogenesis. The changes in free polyamine levels are associated with major developmental stages characterized by increased mitotic activity and differentiation.

Open Access

Priming commercial growing media and soils with dilute sugar solutions was investigated as a means of stimulating beneficial microflora to improve transplant productivity. Muskmelon (Cucumis melo) seedlings were grown in soilless growing medium primed with equal volumes of 50 mm sucrose or trehalose. After priming, the time when 50% of plants showed wilting symptoms was delayed 45 hours and the mean time that seedling xylem tension reached –1.0 MPa was delayed 70 hours compared with watered controls. Sucrose or trehalose priming improved water retention in the presence and absence of plants grown in sphagnum-based medium after an incubation period of ≈24 h, but no improvement occurred when autoclaved medium or acid-washed sand were primed. Light micrographs of primed medium revealed positive staining of opaque material between organic-matter particles with alcian blue, a polysaccharide-specific stain. Sixteen bacterial colonies were cultured in liquid medium from leachate of positive-stained, primed, growing-medium samples and identified via 16S rRNA gene sequencing. Identified colonies were Curtobacterium pussillum, Paenibacillus lautus, Brevundimonas, and 13 Bacillus spp., including well-characterized biofilm producers. Increased soil-moisture retention was the result of a complex, glucose-based, hydrophilic, polysaccharide polymer of bacterial origin that was produced in liquid culture from extracts of primed medium.

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