Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/30/2008
Publication Date: 9/30/2008
Citation: Johnson, R.C., Dajue, L. 2008. Safflower winter survival and selection response relates to Fall Growth morphology and acclimation capacity. Crop Science 48:1872-1880. Interpretive Summary: Safflower (Carthamus tinctorius L.) is a spring sown crop grown in diverse regions world wide, principally for its high quality seed oil. In many areas worldwide, winter hardy or fall sown safflower would provide important management alternatives for farmers. This work was completed to determine the relationship between fall growth and winter survival in safflower, determine if selection of safflower populations would improve winter survival, and how certain physiological factors related to high winter survival potential. We found that low fall plant habit was necessary for winter survival but after that requirement was meet winter survival varied form zero to 90% depending on genotype and environment. Selection from accession populations was successful in improving winter hardiness. Both plant water status and membrane stability were important attribute of winter hardy germplasm. There showed that developing winter hardy safflower cultivars should be possible.
Technical Abstract: Winter or fall planted safflower (Carthamus tinctorius L.) could substantially improve yield compared to spring planting. But the potential for winter survival in safflower and the physiological factors involved are not well understood. Our objectives were to 1)determine the relationship between fall growth patterns and winter survival, 2) assess if phenotypic selection can improve winter survival, and 3) determine if water relations and membrane leakage can distinguish safflower for survival potential. At the two locations and study years, minimum temperatures ranged from -7.2 ºC at Central Ferry, WA in 2004-05 to -19.5 ºC at Pullman, WA in 2005-06. Winter survival ranged from zero to more than 90% depending on genotype and environment. Low plant habit in the fall, less than about 5 mm, was required before significant winter survival could be expected. Phenotypic selection was generally successful in improving winter survival. Higher leaf pressure potential was associated with higher winter survival of accessions BJ-27 in 2004-05. In 2005-06 this was true for pressure potential and membrane stability at the last sampling date. The results show low fall plant habit is critical, but genetic factors associated with cold acclimation and freezing tolerance also determined safflower winter survival. Screening programs to identify accessions with high winter survival should first identify low prostrate types and then use winter field testing, freezing chambers, and tests such as membrane leakage to develop winter safflower cultivars.