Variations in Sugar Content and Dry Matter Distribution in Roots and their Associations with Frost Tolerance in Certain Forage Legume Species

Abstract

Enhancement of cold tolerance is an important aspect in breeding forage legumes in view of increasing interest in extending the cultivation of these crops. Three classes of characters — morphological, morpho‐physiological and biochemical — were considered in selection for cold‐tolerance between and within forage legume species under contrasting growing conditions in the field and a plastic house.

Significant correlation was found between cold damage and concentration of sugars m roots of various forage legume species which were grown under field conditions and subjected to natural frost. Both morphological as well as morpho‐physiological characters were related to cold tolerance in Lathyrus ochrus (L.) DC. This indicated that chemical constituents cannot be used as a sole criterion to select for winter‐hardy strains of this species. Root‐shoot ratio showed a consistent relationship with tolerance to cold irrespective of the growing conditions and season. Hence, sugar concentration and root‐shoot ratio are useful characters in testing species found cold tolerant by other methods. The root‐shoot ratio could be used for testing cold tolerance under controlled conditions. The number of primary branches per plant, root weight and shoot weight may be used as morphological characters in selection for cold tolerance in L. ochrus under field conditions.