Growth environment but not seed position on the parent plant affect seed germination of two Thlaspi arvense L. populations

Authors: Gesch, Russell - Russ; ROYO-ESNAL, ARITZ - Universitat De Lleida; EDO-TENA, E - Universitat De Lleida; RECASENS, J - Universitat De Lleida; Isbell, Terry; Forcella, Frank

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2016
Publication Date: 2/13/2016
Publication URL: http://handle.nal.usda.gov/10113/61884
Citation: Gesch, R.W., Royo-Esnal, A., Edo-Tena, E., Recasens, J., Isbell, T., Forcella, F. 2016. Growth environment but not seed position on the parent plant affect seed germination of two Thlaspi arvense L. populations. Industrial Crops and Products. 84:241-247.

Interpretive Summary: Pennycress (Thlaspi arvense L.) is considered a common weed, but recently researchers have set out to develop it as a new oilseed crop for biofuels. Pennycress seed that matures on the plant has a tendency to go into dormancy for a period of time before it can germinate and produce a seedling. This is called primary dormancy. But even after primary dormancy is broken, sometimes the seed can go into a secondary dormancy state. The specific reasons for the seed going into primary and secondary dormancy are not well understood. Gaining a better understanding of what causes dormancy in pennycress seed will help to manage it as a weed and will also help crop breeders develop non-dormant varieties. In the present study, we conducted experiments to test the influence of the parent plants on the germination of the seeds they produced. Two different pennycress populations, one from Spain and one from the USA, were used for the experiment. Both populations were grown in the field at Almenar, Spain, and Morris, Minnesota, during 2012-2013. When the seeds of these plants were mature they were harvested from the lower (basal) and upper (apical) parts of the plants. Typically, seeds from the basal part mature sooner than the apical part in pennycress. Some of these seeds were used to measure their protein, oil, and carbon content and size, while another portion of these seeds was used to measure total percent germination at temperatures of 5, 8, 11, 14, 17, and 20°C. The germination rate of the seeds also was estimated under a temperature of 8°C, which was found to be optimum for germination. Our results indicated that environmental conditions that the parent plants matured under, particularly temperature and day length, had a greater influence on seed germination, and thus, dormancy level, than did the chemical and physical attributes of the seeds that were measured. These results will benefit agricultural professionals, including scientists, developing strategies to manage pennycress as a weed and for researchers working on domesticating pennycress to make its seeds less dormant for planting as a crop.

Technical Abstract: Thlaspi arvense L. is a common weed found in most temperate regions throughout the world that also shows excellent potential for domestication as an oilseed crop. The complexity of T. arvense seed dormancy presently makes it difficult to manage as a weed or oilseed crop. Therefore, a better understanding of factors controlling seed dormancy will help to develop strategies for managing its weediness and facilitate development of crop genotypes. T. arvense has semi-indeterminate growth and seeds developed at the base of the inflorescence (basal) generally mature sooner than those near the top (apical). However, little is known about the maternal influences on the level of dormancy and germination of basal and apical seeds. To study this, two T. arvense populations, one from Spain and the other from USA, were both grown at field sites in Almenar, Spain, and Morris, Minnesota, USA during the same growing season (autumn 2012-summer of 2013). Basal and apical seeds collected at maturity were analyzed for mass, total protein and carbon content, oil content, and fatty acid profiles. Under controlled environment conditions, seed germination was measured at 5, 8, 11, 14, 17, and 20°C and germination rate estimated at 8°C. Seed position on the inflorescence did not affect germination consistently nor were there clear differences in seed attributes between positions. However, seeds of both populations produced at Almenar had lower germination and were consistently larger and contained higher oil and carbon content than seeds produced at Morris. Results indicate that environmental influences at each growth location played a much larger role in influencing dormancy and germination of seed produced than did the seed attributes measured or position of seed on the inflorescence.