Low temperature growth in a controlled environment of Trifolium repens plants from northern latitudes.
Variation in low temp. growth of several types of white clover collected in N. Britain and sites where low temp. adapted white clover plants may be found were investigated. 25 ecotypes and selected genotypes of 3 cv. were screened for shoot growth at low temp. and irradiance in a cold cabinet. A clinal relationship was indicated between low temp. growth and the winter temp. at the place of origin. 1 ecotype exhibited a marked deviation from this climatic cline; 2 ecotypes exhibited good growth of stolons at soil temp. < 9 deg C. The study indicated that it may be possible to increase the value of white clover in the uplands of Britain by breeding cv. which are capable of active growth at low soil temp. Small-medium-leaved ecotypes produced more shoot growth than small-leaved types. Problems encountered in measuring shoot growth of white clover are discussed.