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a USDA-ARS, Box 646402, Washington State Univ., Pullman, WA 99164-6402
b Beijing Botanical Garden, Room 301, Jingkeyuan No. 18-2, East Road of South Circle, Changping District, Beijing 102200, China
* Corresponding author (rcjohnson{at}wsu.edu).
ABSTRACT
Winter-hardy safflower (Carthamus tinctorius L.) germplasm lines WSRC01 (Reg. No. GP-38, PI 651878) WSRC02 (Reg. No. GP-39, PI 651879), and WSRC03 (Reg. No. GP-40, PI 651880) were developed at the USDA–ARS, Western Regional Plant Introduction Station, Pullman, WA. All three lines were developed from germplasm originating in China and derived from two cycles of recurrent mass selection. Plants of each original accession were fall planted at Pullman (elevation 786 m), and seed of surviving plants was bulked for each cycle. In tests at Pullman and Central Ferry (elevation 206 m), WA, selection increased winter survival an average of 4.1% for WSRC01, 25.3% for WSRC02, and 94.5% for WSRC03, with the increase significant for WSRC02 and WSRC03 (P < 0.05). Average winter survival for WSRC01 was 88%, for WSRC02 84%, and for WSRC03 78%. Survival for spring-type cultivars was zero in all tests. This is the first release of winter-hardy safflower and is expected to be useful in breeding improved winter safflower with potential adaptation to areas of the western United States and the southern Great Plains, in addition to international regions such as the Mediterranean basin and southwest Asia.
For many areas worldwide, winter-hardy safflower (Carthamus tinctorius L.) would provide important management alternatives for farmers. Fall-sown safflower leads to earlier spring growth and development and potentially higher yield than spring-sown safflower. Earlier crop development in the spring, when temperatures are lower and moisture more plentiful, also promotes more efficient water use (Yazdi-Samadi and Zali, 1979). Safflower, as a dicot, could be an excellent rotation crop with winter annual monocots such as wheat in semiarid regions, allowing improved control of grass weeds (Zimmerman and Buck, 1977). Winter-hardy safflower germplasm lines WSRC01 (Reg. No. GP-38, PI 651878), WSRC02 (Reg. No. GP-39, PI 651879), and WSRC03 (Reg. No. GP-40, PI 651880) were developed at the USDA–ARS Western Regional Plant Introduction Station, Pullman, WA, and released by USDA–ARS in 2007. All three lines were developed from germplasm originating in China and are part of the USDA–ARS national safflower germplasm collection at Pullman.
Johnson et al. (2006) showed the potential for winter safflower in evaluations of diverse safflower accessions. In that study, low plant height and prostate habit in the fall were correlated with winter survival. BJ-27 (PI 544017) from Ruicheng County, Shanxi Province, China, had sufficient winter survival to allow fall-planted safflower production in many areas. In addition, greenhouse evaluations of the safflower core collection revealed two accessions, also from China, with prostate habit and the long rosette period expected in winter-type safflower. These accessions, PI 544006 from Runan, in Zhumadian County, Henan Province, and PI 543995 originating from Jingxian County, Hebei Province, were also found to be winter hardy. These three accessions were observed to have considerable plant-to-plant variation for morphological factors such as capitula size, spininess, and leaf morphology, suggesting that variation for other attributes such as winter survival could be present. As a result, mass selection on those promising accessions was completed and tests were conducted to determine if winter survival was improved.
Methods
WSRC01, WSRC02, and WSRC03 were selected from PI 544006, PI 543995, and PI 544017, respectively. Two cycles of recurrent mass selection were completed on each of the original populations. Plots were established at Pullman, WA (786 m elevation; 46.7247 N and 117.1355 W) the second week of September in 2002 and 2003 for the first and second cycles of selection. Seeds were planted in single-row plots 6 m long on 1.5-m centers. Planting depth was 2.5 cm, and seeds were spaced at 8 cm. The plots were arranged in randomized complete blocks with three replications. Cultural practices such as nutrient applications and weed control were optimized. In all plots, plant populations were determined 6 to 8 wk after fall emergence and after the last killing frost in the spring. Winter survival was the percentage of plants that emerged and survived to the spring count. Although predominantly self-pollinating, the surviving plants of each accession were covered with screen cages before blooming to prevent potential outcrossing from other accessions. For the first cycle, seed from surviving plants of PI 544006, PI 543995, and PI 544017 were harvested and bulked in 2003. The second cycle of selection was completed in 2004 to produce WSRC01, WSRC02, and WSRC03. Populations in the fall averaged 68 plants per plot, or 204 total plants. The average number of plants selected was 127 for the first cycle and 186 for the second cycle.
In September 2004, a selection response study was initiated at Pullman and Central Ferry, WA (206 m elevation; 46.6733 N and 117.7541 W). This included the original populations of PI 544006, PI 543995, and PI 544017, selections WSRC01, WSRC02, and WSRC03, and spring-type cultivars Frio (PI 572421), Oleic Leed (PI 5601277), Rio (PI 537693), and Saffire (PI 572475). Frio was registered by Gilbert and Lorance (1966), Oleic Leed by Urie et al. (1979), and Saffire by Mündel et al. (1987). Rio was released by D. Rubis and the Arizona Experiment Station and assigned a PI number in 1988. Entries were randomized in complete blocks with three replications at both locations. Plots were established and winter survival was determined as described above for the selection process.
In 2006–2007, an additional experiment in larger plots was performed comparing WSRC01, WSRC02, WSRC03, and the spring cultivars Girard (PI 525457) and Gila (PI 537692). Girard was registered by Bergman et al. (1989) and Gila was released by D. Rubis and Arizona Experiment Station and assigned a PI number in 1988. Plots consisting of 6 rows, 25 cm apart and 4.5 m long were established at Pullman and Central Ferry and randomized in four complete blocks. Seeding was completed in mid-September at a rate of 38 kg ha–1 and a planting depth of 2.5 cm. Winter survival was determined by counting plants in the fall and spring. Starting at 1 m from the edge of the each plot, plants were counted in the next 2 m in the four central rows.
For both studies described above, data were analyzed using general linear models (SAS Institute, 1990). For analyses of variance, locations and germplasm entries were assumed to be fixed and blocks were random. The LSD at P < 0.05 was used to detect differences among means.
Characteristics
Spring-type cultivars had no winter survival at either of the test environments (Tables 1 and 2 ). For 2004–2005, the three original, unselected accessions (PI 544006, PI 543995, and PI 544017) had winter survival ranging from 24.8% for PI 544017 at Central Ferry to 87.7% for PI 544006 at Pullman (Table 1). Survival of PI 544006 was initially high enough that survival of WSRC01 was not significantly increased by selection. Survival of WSRC02 was increased by selection at Central Ferry but not at Pullman. For WSRC03, selection increased winter survival in all comparisons (Table 1). There was a significant interaction between germplasm entry and location in 2004–2005 (P < 0.05), resulting in a different pattern of survival among selections at Pullman than Central Ferry. At Central Ferry, there were no differences among the selections for survival, but at Pullman, WSRC01 had higher survival than both WSRC02 and WSRC03 (P < 0.05). The lower survival of WSRC02 and WSRC03 was associated with the generally lower temperatures at Pullman. From November 2004 through February 2005, the average minimum temperatures were –0.1°C for Central Ferry and –3.4°C for Pullman. At Central Ferry, a minimum temperature of –7.2°C was observed on 16 Jan. 2005, and for Pullman the minimum temperature was –14.7°C on 15 Jan. 2005.
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WSRC01, WSRC02, and WSRC03 are facultative in the sense that seed production occurs when either spring or fall planted. They also retained some of the variability for capitula size and leaf morphology observed in the original accessions, especially for WSRC03.
Differences in plant growth and development characteristics measured among the selected germplasm were relatively small. When winter planted, anthesis dates occurred in mid-June at Central Ferry (206 m elevation) and early July at Pullman (786 m elevation), and were 2 to 3 d later for WSRC03 than WSRC01 and WSRC02. Maturity dates were late July to early August at Central Ferry and mid- to later August at Pullman. This was 14 to 16 d earlier than when selections were spring planted. All three lines are erect with branching on the upper two-thirds of the plant. When fall planted, plant height at harvest for WSRC01, WSRC02, and WSRC03 averaged 83, 91, and 86 cm, respectively, approximately 9 cm more than when spring planted. Dry flower color is red and capitula spine density variable, but generally light in all lines. Seed oil for all the original accessions is low, ranging from 220 to 230 g kg–1. All lines are linoleic acid types, with average values of 800 g kg–1 linoleic and 136 g kg–1 oleic fatty acids.
This is the first release of winter-hardy safflower. These lines are expected to be useful in breeding improved winter safflower with potential adaptation to areas of the western United States and the Southern Plains, in addition to international regions such as the Mediterranean basin and southwest Asia.
Availability
Small seed quantities of WSRC01, WSRC02, and WSRC03 are available for research from the corresponding author for the next 5 yr, and then through the National Plant Germplasm System and the Western Regional Plant Introduction Station, Pullman, WA. It is requested that appropriate recognition be made if this germplasm contributes to the development of a new breeding line or cultivar.
Footnotes
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.
Received for publication November 21, 2007.
References
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