Cardinal temperatures for germination and early growth of two Lesquerella species |
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| Institution: | 1. USDA-ARS, U.S. Arid Land Agricultural Research Center, 21881 N. Cardon Lane, Maricopa, AZ 85239, USA;2. USDA-ARS, Western Regional Research Center, 800 Buchanan Street, Albany, CA 94710, USA;1. M.Sc. Student of Seed Science and Technology, Agronomy and Plant Breeding Department, Yasouj University, Iran;2. Agronomy and Plant Breeding Department, Yasouj University, Iran;3. Agronomy and Plant Breeding Department, Pardis Aboryhan, Tehran University, Iran;1. Department of Agronomy and Plant Breeding, Ferdowsi University of Mashhad, Iran;2. Department of Agronomy, Shahrekord University, Iran;3. Department of Horticulture, Gorgan University of Agricultural Science and Natural Resources, Iran;1. USDA-ARS National Center for Genetic Resources Preservation, 1111 S. Mason St., Fort Collins, CO 80521, USA;2. Dept. Bioagricultural Sciences and Pest Mgt., Colorado State University, Fort Collins, CO 80523, USA;3. USDA-ARS Water Management Research Unit, 2150 Centre Avenue, Building D, Suite 320, Fort Collins, CO 80526, USA;1. Laboratorio de Fisiología Vegetal, UBIPRO, Facultad de Estudios Superiores-Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla, 54090, Edo. de México, Mexico;2. Royal Botanic Gardens, Kew, Wakehurst Place, West Sussex, RH17 6TN, UK;3. Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria, 04510, D.F., Mexico;4. Laboratorio de Farmacognosia, UBIPRO, Facultad de Estudios Superiores-Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla, 54090, Edo. de México, Mexico;1. College of Pharmacy, Dalian Medical University, 9 Western Lvshun South Road, Dalian 116044, China;2. Research Institute of Integrated Traditional and Western Medicine of Dalian Medical University, Dalian 116011, China |
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| Abstract: | Lesquerella (Lesquerella fendleri) is a potential alternative crop that is being studied for commercial oilseed production. Understanding the minimum temperatures for germination and seedling growth is important for determining potential areas for lesquerella production. The objectives of this study were to determine the cardinal temperatures for germination and seedling growth, and to screen ecotypes for germination and growth characteristics. A temperature gradient table arrangement was used to observe seed germination over a range of temperatures, and time to germination and shoot appearance. Times to 5 mm root length and 5 mm shoot length were also measured to assess cardinal temperatures for seedling survival and growth. Two different species were examined, L. fendleri and a species we refer to as ‘L. pallida aff.’ because it differed from typical L. pallida plants in chromosome number and in oil quality. We concluded that both germination and growth of L. pallida aff. occurred fastest at 22 °C, whereas L. fendleri germinated earlier at 18 °C, but grew faster at 22 °C. L. pallida aff. also had lower germination than L. fendleri over the range studied. Non-dormant seeds of improved lines of L. fendleri had better performance at temperatures above 22 °C than did unimproved accessions. Lines of L. fendleri selected for high oil content and salt tolerance had similar temperature requirements for germination except for improved line WCL-LO3, the current line being used in production. This line had optimal temperatures 6 °C higher for germination and growth than the other improved lines. Accessions of L. fendleri collected from elevations above 2000 m performed better at warmer temperatures, whereas those collected from elevations below 2000 m tended to perform better at cooler temperatures. Dormant seeds of L. fendleri germinated more quickly at low temperatures and had lower base (<3 °C) and optimal (22 °C) temperatures than non-dormant seeds (>7 °C and 28 °C, respectively). We speculate that this partial dormancy trait allows populations of L. fendleri to exploit a wider range of temperature conditions in the wild in order to thrive in extreme environments. |
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