Soil moisture and temperature affect condensed tannin concentrations and growth in Lotus corniculatus and Lotus pedunculatus

Abstract

Maku big trefoil and Dewey birdsfoot trefoil were grown at 14/10, 20/16, 26/22 and 32/28�C (14/10 h) in growth cabinets. Growth rates and condensed tannin (CT) concentrations were measured as soil moisture was changed from field capacity (FC) to 20% FC to FC again in three regrowth cycles. Seasonal dry matter accumulation and CT concentrations were also measured on these cultivars together with Sharnee big trefoil, Monarch cicer milkvetch, Chemung crownvetch and WL605 lucerne at two sites in the field. Condensed tannin concentrations were not greatly affected by temperature alone. However, moisture stress induced proportionately larger reductions in growth rates of big trefoil as temperature increased, and correspondingly larger rises in CT concentrations. Condensed tannin concentrations in birdsfoot trefoil were largely unaffected by these factors. In big trefoil, the responses in CT levels and growth rates continued even when soil moisture was returned to FC. Low temperature did not appear to affect CT concentrations in big trefoil, but caused some slight elevation in concentrations in birdsfoot trefoil. In the field, CT levels in the big trefoil cultivars, and in birdsfoot trefoil, were elevated in summer and autumn, when temperatures were high and periods of soil moisture stress occurred. The potential for elevated CT levels in big trefoil appears to be enhanced when growth rates are reduced by moisture stress and temperaturs are high. Big trefoil should be carefully screened for CT concentrations in the process of cultivar development. High CT levels are not a problem in birdsfoot trefoils such as Dewey.

Effect of plant development during first and second growth cycle on chemical composition, condensed tannins and nutritive value of three sainfoin (Onobrychis viciifolia) varieties and lucerne

“…(1994) reported that Lotus pedunculatus had more CT when grown at 30°C than 20°C. Similarly, Anuraga et al. (1993) observed higher CT levels in Lotus pedunculatus but not in Lotus corniculatus at 30°C.…”

Responses ofLotus corniculatus to environmental change. 2. Effect of elevated CO2, temperature and drought on tissue digestion in relation to condensed tannin and carbohydrate accumulation

“…Moreover, both condensed tannin concentration and plant re-growth at 30°C were severely reduced after the plants were cut back, which could indicate low levels of storage carbohydrates in the roots prior to harvesting. In a study by Anuraga et al, 14 low temperatures have been reported to elevate condensed tannin concentrations in L corniculatus whilst high temperature and drought stress increased condensed tannin levels in L uliginosus indicating species differences in condensed tannin biosynthesis in response to temperature.Briggs and Schultz 31 observed that, contrary to expectation, investment in condensed tannin accumulation was not at the expense of plant growth, but was positively correlated with shoot size. In the current work, plants of genotype S41 had higher condensed tannin concentrations relative to S33 and S50, but their growth rate and daily biomass production were comparable.…”

“…Some reports on the effects of temperature and drought on condensed tannin accumulation in Lotus corniculatus have been published 14,15 but the effects of elevated CO 2 or a combination of environmental variables have not been reported. Furthermore, no information is currently available on the relationship between environmental growth conditions and condensed tannin accumulation and subsequent effects on tissue digestion.…”

“…Changes in growth temperature and drought stress have also been reported to cause¯uctuations in condensed tannin concentrations in Lotus. 14,15 As condensed tannins contain no nitrogen, their concentration should alter when an imbalance in the C/N ratio occurs such as with an increasing environmental CO 2 concentration. Indeed the importance of the C/N balance in legumes in relation to condensed tannin biosynthesis was identi®ed by Briggs 16 following measurements of reduced condensed tannin concentrations in Lotus corniculatus that received no nitrogen fertiliser, resulting in a large carbon demand for nitrogen ®xation.…”

Morphology and agronomic performance of white clover with increased flowering and condensed tannin concentration

“…If concentrations could be maintained at the top of this range there may be advantages for ruminant nutrition and bloat prevention, so the reasons for variability need to be determined. A range of biotic and abiotic factors (soil moisture and fertility, light intensity, animal grazing) can influence CT concentrations (Briggs 1990;Anuraga et al 1993;Gebrehiwot et al 2002), with varying responses amongst plant species. In this study, CT concentration was affected by the stage of flower development, being highest when flowers were in full bloom, and low in green buds or senescent flowers.…”