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Toona
About: Toona is a research topic. Over the lifetime, 105 publications have been published within this topic receiving 1251 citations.
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TL;DR: Contrary to expectation, photosynthetic responses to light × nutrient treatments did not correlate with degree of shade tolerance accorded each species by rainforest ecologists.
Abstract: Species with contrasting shade tolerance were grown under three light by two nutrient treatments. Gas exchange by intact leaves, leaf disk O2 evolution and chlorophyll fluorescence were measured. In shade-tolerant evergreen species (Argyrodendron sp., A. trifoliolatum and Flindersia brayleyana) photosynthetic activity of seedlings in air at light saturation (A) was lower under weak (30 pmol quanta m-2 day-1 ), compared with medium (130) or strong light (535). In Toona australis, a shade-intolerant and deciduous tree, A was reduced 44% from strong to weak light treatment on high nutrients (71 mg N L-1 nutrient solution). Nevertheless, nitrogen-use efficiency for leaf photosynthesis was highest in Toona under all growing conditions and, with higher specific leaf area, probably contributes towards fast occupancy of sites which underlies early succession in this species. All species made photosynthetic and respiratory adjustments from strong to medium to weak light, which resulted in a lower light compensation point (Q0). Such adjustments were accentuated by low nutrient supply (1.0 mg N L-1 nutrient solution) and were especially pronounced for shade-intolerant Toona. Reduced Q0 in Toona was accompanied by lower A and light saturation point (QA). Both species of Argyrodendron showed no decrease in QA despite reduction in Q0 under weak light.Contrary to expectation, photosynthetic responses to light × nutrient treatments did not correlate with degree of shade tolerance accorded each species by rainforest ecologists.
125 citations
TL;DR: Seedling trees of Argyrodendron sp.
Abstract: Seedling trees of Argyrodendron sp., A. trifoliolaturn, Flindersia brayleyana and Toona australis were grown for c. 180 days under one of three light regimes with either of two nutrient levels (6 treatments in all). Light regimes spanned the range of environmental conditions which these species would normally experience in northern Queensland rainforest: deep shade (1.3 mol quanta m-2 day-1, equivalent to forest floor), moderate light (5.6 mol quanta m-2 day-1, comparable to midcanopy), and strong light (23 mol quanta m-2 day-1, matching daily irradiance of exposed crowns). Long-term shade tolerance in Argyrodendron sp. and A. trifoliolaturn was associated with limited responses in growth and leaf anatomy to low light and nutrients. Starch accumulation in leaves under all treatments, and especially low nutrients, implied that supply of photoassimilate exceeded demand. Such a conservative carbon economy, plus the accumulation of stem P reserves, even in a weak light environment, is consistent with a protracted existence as part of a forest floor community. By contrast, shade-intolerant Toona is an early successional species and lacks such adaptive features. Instead, light and nutrients had a strong interactive effect on growth. Flindersia, with a broad tolerance to sun and shade, was intermediate in growth response and leaf adjustment, which is consistent with its success across a wide size range of forest gaps.
112 citations
TL;DR: From a literature search for reports on the chemical constituents of these plants, most constituents were found to be quinone derivatives or other compounds with unsaturated carbonyl groups.
Abstract: Seventy-five Myanmar timber extracts belonging to 27 families were examined for their leishmanicidal activities. Some timber extracts had significant leishmanicidal activity, especially extracts of Millettia pendula, which exhibited the most potent activity (MLC 3.1 μg/ml, MIC 1.6 μg/ml). Other timber extracts showing potent activity included those from Cedrela serrata, Cedrela toona, Cordia fragrantissima, Calophyllum kunstleri, Dalbergia cultrate, Grevillea robusta, Haplophragma adenophyllum, Michelia champaca, and Tectona grandis. From a literature search for reports on the chemical constituents of these plants, most constituents were found to be quinone derivatives or other compounds with unsaturated carbonyl groups.
73 citations
TL;DR: The seeds of Owenia acidula of Ovenia venosa were found to contain a simple limonoid and a derivative of the cyclopropane protolimonoid glabretal which has also been found in the timber of Aglaia ferruginea as discussed by the authors.
64 citations
TL;DR: In vivo evaluation of tree leaves of Azadirachta indica, Melia azedarach, Morus alba and Leucaena leucocephala could serve as promising, alternate feed resource for ruminants, according to preliminary screening by in vitro gas production technique.
57 citations