VARIATIONS IN SUGAR CONTENT AND DRY-MATTER DISTRIBUTION IN ROOTS AND THEIR ASSOCIATIONS WITH FROST TOLERANCE IN CERTAIN FORAGE LEGUME SPECIES

Enhancement of cold tolerance is an important aspect in breeding forag e legumes in view of increasing interest in extending the cultivation of these crops. Three classes of characters - morphological, morpho-ph ysiological and biochemical - were considered in selection for cold-to lerance between and within forage legume species under contrasting gro wing conditions in the field and a plastic house. Significant correlat ion was found between cold damage and concentration of sugars in roots of various forage legume species which were grown under field conditi ons and subjected to natural frost. Both morphological as well as morp ho-physiological characters were related to cold tolerance in Lathyrus ochrus (L.) DC. This indicated that chemical constituents cannot be u sed as a sole criterion to select for winter-hardy strains of this spe cies. Root-shoot ratio showed a consistent relationship with tolerance to cold irrespective of the growing conditions and season. Hence, sug ar concentration and root-shoot ratio are useful characters in testing species found cold tolerant by other methods. The root-shoot ratio co uld be used for testing cold tolerance under controlled conditions. Th e number of primary branches per plant, root weight and shoot weight m ay be used as morphological characters in selection for cold tolerance in L. ochrus under field conditions.