The study of variability of agro-morphological characteristics of white clover accessions from other countries in Latvian climate conditions

White clover (Trifolium repens L.) is one of the most important forage legumes in temperate grasslands because of its large spread, good adaptability, high nutritive value combined with a good palatability and by its nitrogen-fixing capacity (Balan, 2007). The evaluation of the white clover germplasm collections under field conditions is recognized as a general method to estimate biological diversity. During the years 2006-08 experimental field trials were performed at the Research Institute of Agriculture in Latvia. A white clover collection of 46 samples with large-scale geographic origins from 19 countries was established. Wild populations gathered in Latvia and Lithuania were also included in the collection. Native cultivar ʹDaileʹ as the standard was used. All three white clover varietas (var.) - silvestris, hollandicum, and giganteum - were represented in the collection. A huge diversity of morphologically different plants was observed among the collected samples. Winter-hardiness, earliness, growth intensity, time of flowering, weight of leaves and flower heads, length of sprouts, size of the central leaflet, etc, are the important traits of the genetic variability. Among the white clover accessions were samples with untraditional reddish-rose-colored flower heads. The aim of the study was to select valuable source material for future breeding with a good possibility of adaptation in the changeable climate and different soils in Latvia, with high productivity, good disease resistance, of many yearsʹ standing in the sward, etc. Our research shows that large genetic variability exists within the investigated white clover collection. The evaluation of samples of our white clover collection in the agro-climatic conditions of Latvia shows that some varieties are featured with several morphological qualities and could be appropriate as promising material for the creation of a new variety. These are ʹDubrauxʹ (Czech Republic/Slovakia); ʹGigantʹ (Belgium); ʹHuiaʹ (New Zealand) and local wild population ʹEcotype 2005ʹ, which stand out for their winter-hardiness, earliness, production of a large foliage surface and produce high seed yield.