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Comparisons of Floral Response of Seed Lots of Dollard Red Clover, Trifolium pratense L. 1
Author(s) -
Bula R. J.,
May R. G.,
Garrison C. S.,
Rincker C. M.,
Dean J. G.
Publication year - 1965
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1965.0011183x000500050016x
Subject(s) - crop , red clover , library science , biology , horticulture , agronomy , computer science
The accumulated evidence (1, 2, 4, 5) suggests that one of the basic physiological differences between the two red clover types is that the medium varieties are capable of developing flowering stems without a period of exposure to near or sub-freezing temperatures. In contrast, the mammoth types apparently require exposure to low temperatures before floral stems will elongate and mature. Germ plasm of both types is being utilized in red clover breeding programs and varieties have been released that combine both types resulting in a varietal population with a diverse genetic base. Dollard red clover is an example of such a variety. Consequently, a diversity of plants ranging from completely rosette types to completely floral types can be found during the seedling year in the varietal populations. Bird (1) described five plant types based on the degree of floral stem development that can be found within the varietal population of Dollard during the seedling year. Smith (5) called attention to such plant type diversity as it may affect the maintenance of a variety through successive generations of increase. Steppler and Raymond (6) reported that a LaSalle seed lot, harvested from a seeding year stand, contained a higher percentage of floral-type plants than a seed lot harvested from the second year production of this seed field. They observed that plants producing seed during the seedling year usually failed to survive the following winter. Smith (5) working with Wisconsin common red clover also found a lower survival rate for the "flowering-types". Therrien and Smith (8) reported that the percentage of winter killing during the first winter was higher for the flowering plants than for the nonflowering plants of Dollard red clover. The question arises as to whether varietal populations derived from the combination of single-cut and double-cut germ plasm can be maintained through successive generations of seed increases. This question becomes more important when these increases are accomplished in vastly different environmental regimes such as those that prevail in the north central area of the U. S. where these varieties