Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Clammy (Physalis heterophylla Nees.) and smooth (P. virginiana Mill. var. subglabrata (Mackenz. and Bush) Waterfall) ground-cherry are perennial herbs that grow in cultivated fields, roadsides, pastures, and open woodlands. It was postulated that both species are capable of surviving in highly disturbed habitats because of their extensive root systems and their capacity to regenerate from root fragments. Field and greenhouse experiments were conducted in 1991 and 1992 to investigate the effects of root fragment size, depth of root burial, root fragment orientation at planting, plant growth stage at the time of root fragmentation, and origin of the root fragments, on their subsequent capacity to regenerate. The root systems of both species consisted of short feeding roots and long perennating roots. Only the long root type was capable of vegetative regeneration. Lateral long roots branched from the main vertical tap root two to ten cm below the soil surface. These lateral long roots grew horizontally before turning down at various distances from the main vertical tap root. Clammy ground-cherry produced more long roots and underground shoots than smooth ground-cherry.;Both species were capable of regenerating from root fragments as short as 2.5 cm and could send up shoots from at least a 15 cm soil depth. No root fragment survived at the soil surface. Orientation had no effect on the capacity of the two species to regenerate from root fragments. In both species significantly fewer fragments sampled from plants at the fruit dispersal stage regenerated compared to those obtained from the early vegetative stage. More than 90% of root fragments with visible buds regenerated, whereas 50% of root fragments without visible buds did so. In both species portions of the horizontal laterals close to the shoot had the lowest potential for regeneration.;In herbicide field studies only glyphosate ((N-phosphonomethyl) glycine) and atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) at 2.24 and 2.50 kg ai ha{dollar}\sp{lcub}-1{rcub},{dollar} respectively, significantly reduced shoot density in smooth ground-cherry stands.;The two species could survive in disturbed agricultural habitats because of their deep and extensive root systems with buds and their capacity to regenerate with or without fragmentation.



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