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Effect of White Clover Mosaic Virus and Clover Yellow Mosaic Virus on Pollen Germination in ‘Dollard’ Red Clover, Trifolium pratense L 1
Author(s) -
Guthrie James W.,
Slinkard Alfred E.
Publication year - 1964
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/cropsci1964.0011183x000400030034x
Subject(s) - mosaic , white (mutation) , biology , red clover , crop , pollen , germination , horticulture , agronomy , botany , history , ancient history , genetics , gene
study, not lower than those that prevail in interior northern states such as Montana nd Minnesota where varieties such as Troy and Park are sufficiently winterhardy. As noted, Troy, Park, and all other varieties from latitudes below 52 ° winterkilled almost completely. The foliar "curing" of the indigenous Alaskan red rescues, and the apparent association of ’this phenomenon with superior winter survival, is believed to indicate growth cessation and onset of dormancy in preparation for winter by those accessions adapted to fall conditions at .this latitude. It is not known what factors induced this differential plant response but it is probable that a climatic factor that differs with latitude such as photoperiod may have been causal. Pohjakallio et al. a grew several varieties of red clover in Finland that were adapted to mid-temperate latitudes. The red clovers displayed very poor winter survival after having been exposed to the relatively long,, prevailing arctic photoperiods during the previous growing season. However, the same varieties exhibited markedly superior winter survival after having been subjected to shortened photoperiods during the previous season, photoperiods more similar to those that occur in their area of adaptation. More recently Hodgson 4 has reported that physiological changes within alfalfa plants in preparation for winter were related to photoperiod. An alfalfa variety adapted to the Midwest and grown in subarctic Alaska developed less resistance to freezing when grown under the long prevailing photoperiods than when shorter photoperiods similar to its area of adaptation were imposed uring late summer and autumn. In the present study, poor winter survival of grasses from more southern latitudes, superior winter survival of grasses from nothern latitudes, and the observed fall dormancy of indigenous Alaskan red rescues suggest hat adaptation .to late summer and autumn climatic influences peculiar to north latitudes is requisite to optimum winter survival of plants in the subarctic.