Submitted to: Canadian Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2006
Publication Date: 7/1/2006
Citation: Johnson, R.C., Dajue, L., Bradley, V.L. 2006. Autumn growth and its relationship to winter survival in diverse safflower germplasm. Canadian Journal of Plant Science. 86:701-732. Interpretive Summary: In many areas, winter hardy safflower would provide important management alternatives for farmers. Winter safflower would enhance autumn and early spring plant development so that higher seed yield would be expected than with spring sowing. With earlier maturity, crop development of winter safflower would occur when temperatures are lower and moisture more plentiful than for spring sown safflower. Safflower, as a dicot, is potentially an excellent rotation crop with winter annual monocots such as wheat in semiarid regions. Our objective was to measure several autumn growth factors including plant habit and relate those measurements to winter survival in a diverse set of safflower germplasm. The results of this study lead to two overall conclusions. First, for the material studied, prostrate habit in the autumn was an essential component of winter survival potential but by itself did not ensure a high level of winter hardiness and survival. Second, BJ-27 had the highest winter survival of the accessions tested, sufficiently high to be used to develop safflower for autumn planting in many areas.
Technical Abstract: Autumn-planted safflower (Carthamus tinctorius L.) would provide management alternatives in crop rotations and potentially increase yield. Our objective was to relate several autumn growth factors to winter survival in a diverse set of 11 safflower accessions grown at Central Ferry and Pullman WA, USA. Safflower was sown in September 2002 and 2003 and plant population counts were taken 6-8 weeks after emergence. A subsample from each plot was also taken for measurements of plant habit, plant height, stem diameter, and shoot dry weight. After the last frost in the spring, plant counts were taken to calculate winter survival. The Pullman plots in 2003-04 were lost during an usually cold and windy November but survival in the remaining three environments ranged from 90% for BJ-27, an introduction from China, to zero for the cultivar Saffire. Winter survival was negatively correlated with plant habit (r = -041**, n=98) and plant height ( r = -0.29**, n=98). However, some accessions with low plant habit (prostrate growth) and low height values had relatively poor survival. The results show that BJ-27 had sufficient survival to develop winter safflower for many areas. Prostrate plant habit can predict the potential for winter survival, but physiological factors related to the cold acclimation process appeared to determine if that potential is realized.