Growth in herbaceous perennials

Graduation date: 2000Several studies of herbaceous perennials have addressed the effects of\ud environmental factors during and after production, inherent cold hardiness, and\ud post-harvest handling procedures to enhance flowering and growth during\ud establishment. The regrowth of both woody and herbaceous forage plants\ud following establishment is reported to be directly related to reserve-nitrogen\ud content. Plants with higher nitrogen reserves grow sooner and produce more\ud growth than plants with low reserves.\ud The first objective in my study, carried out in the greenhouse and outdoors,\ud was to identify any relationship between initial plant size and the regrowth of\ud fourteen herbaceous perennials from five nursery sources. Of the varieties\ud analyzed, six showed differences in growth between nurseries when grown\ud outdoors, but it appears this was not due to their initial plant size.\ud The second objective was to determine whether reserve nitrogen (N) content\ud or the level of reserved total nonstructural carbohydrates (TNC) had an effect on\ud regrowth. In this greenhouse experiment, six out of nine varieties that had higher\ud levels of reserve N per plant tended to grow more. In contrast, five varieties\ud showed more growth with higher levels of reserve TNC per plant. This suggests\ud that reserve nitrogen may have more effect than carbohydrates on the regrowth of\ud perennial plants during establishment.\ud The third objective was to determine the timing of N uptake from soil applied\ud N after establishment. For this greenhouse experiment, double-labeled\ud depleted ammonium nitrate was applied to plants of Astilbe chinensis 'Pumila' 10 d\ud after they were transplanted in the greenhouse. The uptake started soon after the\ud application; 40% of the ¹⁵N was detected by Day 10, and then leveled off. This\ud study suggests that herbaceous and woody perennials are similar in their\ud requirement for reserve N for new growth.\ud In general, the growth of herbaceous perennials appeared to be related to\ud reserve N content rather than to initial plant size or levels of stored carbohydrates.\ud However, this is preliminary study, and more studies are necessary for further\ud investigation.\ud regrowth of\ud perennial plants during establishment