Submitted to: Industrial Crops and Products
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/2/2006
Publication Date: 1/4/2007
Citation: Adam, N.R., Dierig, D.A., Coffelt, T.A., Wintermeyer, M., Mackey, B.E., Wall, G.W. 2007. Cardinal temperatures for germination and early growth of two Lesquerella species. Industrial Crops and Products 25:24-33. Interpretive Summary: Lesquerella is a new oilseed crop. Before farmers grow a new crop, it is important to determine temperatures for optimum seed germination in order to select the best planting dates. Lesquerella seeds from various sources were germinated under different temperatures. Seeds germinated better at warmer temperatures if they were from improved lines and produced at elevations above 600m. Seeds germinated better at cooler temperatures if they were from wild parents, freshly harvested, and produced at elevations below 600 m. Optimal temperature for germination was slightly less than 20°C, while optimal temperature for seedling growth was slightly greater than 20°C. Growers can expect better performance over a range of temperatures as a result of selection and breeding and if daily temperatures are above 20°C.
Technical Abstract: Lesquerella (Lesquerella fendleri Gray) is a potential alternative crop that is being studied for production. Understanding the minimum temperature of germination and of seedling growth is important for determining potential areas for lesquerella production. The objectives of this study were to determine cardinal temperatures of germination and seedling growth, and to screen ecotypes for germination and growth characteristics. A temperature gradient table was used to allow seed germination over a range of temperatures and time to germination and shoot appearance was observed. Time to 5 mm root length and time to 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.’ since it differed from typical L. pallida plants in chromosome number and in oil quality. We concluded that both germination and growth of this species occurred most quickly at 22°C, while L. fendleri germinated quicker at 18°C but grew quicker at 22°C. L. pallida aff. also had a lower germination percentage 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-LO2, the current line being used in production. This line had optimal temperatures 6°C higher for germination and growth compared to others improved lines. Accessions of L. fendleri collected from elevations above 2000 m performed better at warmer temperatures, while 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 allows populations of L. fendleri to exploit a greater range of temperature conditions in order to thrive in extreme environments.