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  • Author or Editor: B.R. Smith x
  • Journal of the American Society for Horticultural Science x
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Abstract

The rooting of strawberry runner tips was studied in relation to soil moisture tension in the rooting medium and soil moisture supplies to the mother plants. In the first weeks of runner establishment the rate and amount of top growth was controlled largely by the moisture supply to the mother plant. Growth was decreased as moisture stress on the mother plant was increased. For the most part, root habit of the runner was independent of influence from the mother plant. Variations in soil moisture tension in the rooting medium had little influence on top growth of the runner except for leaf area but did influence root growth significantly. Secondary root growth was restricted by both very wet and very dry soil conditions. The results confirmed that the initial number of main roots formed and their penetration was independent of moisture tension in the rooting medium. Organic matter additions to the rooting medium did not influence moisture effects appreciably.

Open Access

Polyphenols were analyzed in expanding buds and developing leaves of pecan [Carya illinoensis (Wangenh.) C. Koch] cultivars with varying responses to Cladosporium caryigenum (Ell. et Lang. Gottwald), the organism causing scab. Plant tissue extracts were examined by high-performance liquid chromatography using a water: methanol gradient to separate polyphenolic components on a C-18 reversed phase column. A diode-array detector was used to identify profile components by retention times and computer matching of ultraviolet spectra to standard compounds in a library. Concentrations of these polyphenols were compared throughout the growing season in leaves of pecan cultivars with low (`Elliott'), intermediate (`Stuart'), and high (`Wichita') susceptibility to scab; during susceptibility to infection by Cladosporium caryigenum from 16 cultivars; and in `Wichita' leaf discs with and without scab lesions. The major polyphenolic constituent of tissues for all cultivars was identified as hydrojuglone glucoside, which was detected in intact buds and leaves throughout the growing season. Hydrojuglone glucoside concentration increased concomitantly with leaf expansion and then declined slowly. Juglone was barely, if at all, detectable, regardless of leaf age. No correlation was found between cultivar susceptibility to pecan scab and the levels of either juglone or hydrojuglone glucoside in the healthy leaves of 16 cultivars. Leaf tissue with scab lesions had significantly higher juglone and hydrojuglone glucoside levels than leaf discs without scab lesions. Chemical names used: 4-8-dihydroxy-1-naphthyl b-d-glucopyranoside (hydrojuglone glucoside); 1,5-hydroxy-naphthoquinone (juglone).

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