Regrowth of white clover after chilling assimilate partitioning and vegetative storage proteins

International audienceUnder temperate climates, grassland species are subjected to over-wintering which may significantly influence their early spring growth capacity, In white clover (Trifolium repens L.), it is known that overwintering capacity can differ among cultivars. Ability of this forage legume to recover from winter damage mill, therefore, have a great influence on its persistence in grass-clover associations. Experiments were undertaken with two different white clover cultivars (Huia and AberHerald). Leaf appearance rate, dry matter distribution, C-14 assimilate partitioning, and vegetative storage protein accumulation were determined in plants subjected to a 4-wk chilling period (5/0 degrees C, day/night) and subsequent warmer temperatures (15/10 degrees C), and compared with control plants (20/15 degrees C), Chilling treatment decreased leaf appearance rate, with AberHerald producing more leaves than Huia, This can be considered as a major aspect of cold adaptation strategy because leaf appearance rate controlled carbon acquisition. Low temperature increased dry matter partitioning to below-ground tissues. AberHerald allocated more assimilates to stolons than Huia, Accumulation of a 17.3-kDa protein, believed to act as a,vegetative storage protein, also increased after the chilling treatment, Regrowth was characterized by rapid mobilization of the 17.3-kDa protein in stolons and by preferential carbon allocation to stolen apices, AberHerald showed a higher regrowth potential than Huia in view of its morphological and physiological characters which include carbon acquisition and assimilate partitioning patterns, favoring shoot regrowth and acquisition of stolen reserves

Overwintering of Trifolium repens L. and succeeding growth : Results from a common protocol carried out at twelve European sites

A common experimental protocol was followed at 12 sites in Europe to study the development of two clover cultivars (AberHerald and Huia) grown in association with a ryegrass cultivar throughout their annual cycle. The duration of the experiment was between 1 and 3 years at each site. Detailed information about the morphogenesis and carbohydrate reserves of white clover during winter and the subsequent productivity of clover plants during the growing season was collected. Yield of the companion ryegrass was also measured at several harvests during the growing season and grass tiller density was recorded several times during winter. There was wide variation among sites and between years in climatic conditions, in the growth characteristics and chemical composition of the two cultivars, and in the tiller density of the ryegrass. The relative performance of the two cultivars varied among sites but AberHerald generally outperformed Huia. Major changes in plant characteristics (morphology, population size, chemical composition, etc.) occurred during overwintering. This paper presents a preliminary analysis of the effects of site, clover cultivar and sward age (years) on various plant characteristics. It is established that the data provide a unique basis for modelling the effects of a wide range of environmental conditions and plant properties on the performance of white clover in mixed swards. A modelling approach that seeks to replace site and year by climatic variables characterizing each site by year combination is developed in two companion papers

Overwintering and growing season dynamics of Trifolium repens L. in mixture with Lolium perenne L. : A model approach to plant-environment interactions

In attempting to increase the reliability of clover contribution in clover/ryegrass systems it is important to understand the roles of (1) specific traits of the clover genotype (2) climate and (3) their interactions in determining clover behaviour in swards. Overwintering and spring growth of white clover (cultivars AberHerald and Huia) grown in binary mixtures with perennial ryegrass were measured at 12 European sites ranging in latitude from Reykjavik, Iceland (64°30' N) to Pordenone, Italy (46°30' N). In the overwintering period, tiller density of the grass was assessed and detailed morphological and chemical measurements were made on the clover at each sampling time. During the growing season, the clover contribution to total available biomass was recorded. Detailed climatic data were available at all sites. The annual growth cycle of swards was divided into four functional periods (spring, summer, autumn and winter). Within each functional period community responses were modelled. The models incorporated independent biotic variables characterizing each community within each site at the start of the period and independent variables characterizing the climate at each site during the period. The models were linked dynamically by taking, as response variable(s) for a functional period, the independent biotic variable(s) of the succeeding period. In general, the modelling strategy was successful in producing a series of biologically meaningful linked models. Essential prerequisites for this were (a) the establishment of a well-devised common protocol prior to the experiment and (b) the extensive gradients of climatic and other variables obtained by using numerous sites. AberHerald generally performed as well as, or better than, Huia throughout the annual cycle across the range of climatic conditions encountered, and especially under low temperature conditions in winter and autumn. Clover leaf area index appeared to be a key variable in determining clover performance over winter and through the following growing season. Grass tiller density had a strong negative effect on clover content in spring but only at low temperatures. This emphasizes the importance of a high clover leaf area index in autumn as the main biotic factor related to spring clover content in milder conditions. The importance of climatic variables in the models is their use in explaining the reliability of the contribution of clover in clover/ryegrass systems. Temperature was the primary climatic determinant of clover response in all periods, having a direct effect on clover content and leaf area index or mediating the effect of the associate species. Radiation strongly influenced clover dynamics during winter and spring but not in the other periods, possibly because it was confounded with the effect of higher temperature. Precipitation was positively related to clover growth during spring and autumn and was related to tiller density in a complex manner during autumn and winte

A model approach to white clover summer dynamics at twelve European sites

vokPA

Overwintering of Trifolium repens L. and Succeeding Growth: Results from a Common Protocol carried out at Twelve European Sites

vokEKO/Karil

Overwintering and Growing Season Dynamics of Trifolium repens L. in Mixture with Lolium perenne L.: A Model Approach to Plant-environment Interactions

vokEKO/Karil