Theses and Dissertations at Montana State University (MSU)
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Item Evaluating the genetic and phenotypic responses of Camelina sativa to heat stress(Montana State University - Bozeman, College of Agriculture, 2023) Smith, Brian Edward; Chairperson, Graduate Committee: Chaofu LuCamelina sativa (L.) Crantz is a low-input oilseed crop with a unique fatty acid profile in its seed oil. Camelina oil can be used in biodiesels, jet fuels, and industrial lubricants. Improving the abiotic stress tolerance of camelina is a crucial step for increasing agronomic viability. Climate change is threatening production of camelina with rising global temperatures and shorter growing seasons. Elucidating the phenotypic and genetic responses to high temperatures is essential for successful breeding of heat tolerant camelina varieties. Three experiments were conducted to understand these responses. Two genotypes, Suneson (MT5) and Pryzeth (MT102) were exposed to a transient 14-day heat stress during the reproductive stage and evaluated for agronomic and seed quality traits along the main stem. Next, a mapping population consisting of 257 recombinant inbred lines (RILs) were grown under the same temperature regimes for 14 days beginning at the onset of the reproductive stage. Finally, reproductive tissues undergoing heat stress from two genotypes with contrasting heat responses, RIL23 and RIL167, were examined with RNA sequencing, and the phenotypes along the main stem were compared. From the phenotype evaluation, both MT5 and MT102 were significantly impacted by heat. Both genotypes experienced reductions in seed and pod size, seed weight, and total oil contents. As reported in other oilseed crops, camelina is negatively affected by heat, characterized primarily by lower yield and reduced oil content. The QTL analysis identified several key gene regions with co-located traits on chromosomes 8, 10, and 12. This demonstrates the ability to identify heat-responsive gene regions via phenotyping along the main stem. The transcriptomes of RILs 23 and 167 contrasted in both sampled tissue types, with RIL23 appearing more responsive to heat. Phenotypic analysis of these genotypes confirmed the transcriptional differences, as RIL23 was more resistant for several traits associated with fertility. These studies provide resources and protocols for future studies that may assist in improving the heat-tolerance of camelina.Item Extending cool season production of vegetables in the high tunnel: balancing heat and light(Montana State University - Bozeman, College of Agriculture, 2019) Baumbauer, David Alan; Chairperson, Graduate Committee: Mac Burgess; Macdonald H. Burgess was a co-author of the article, 'The Montana high tunnel growers survey - identifying grower practices and concerns' submitted to the journal 'HortTechnology' which is contained within this thesis.; Macdonald H. Burgess was a co-author of the article, 'Row cover influences light transmisson, air and soil temperatures in the high tunnel during Spring and Fall' submitted to the journal 'Journal of agricultural and forest meteorology' which is contained within this thesis.; Macdonald H. Burgess was a co-author of the article, 'Season, sowing date, and row cover influence the production of cool season vegetables in the moveable high tunnel' submitted to the journal 'Canadian journal of plant science' which is contained within this thesis.; Colleen B. Schmidt and Macdonald H. Burgess were co-authors of the article, 'The influence of low daily light integral on the growth of baby kale, lettuce and spinach' submitted to the journal 'HortScience' which is contained within this thesis.Montana high tunnel growers face challenges associated with being at a northern latitude and high elevation. The wide seasonal fluctuation in photosynthetically active radiation coupled with wide diurnal temperature swings produces a dynamic growing environment within the high tunnel. This dissertation is comprised of four studies investigating the management of light and temperature and their influences on high tunnel grown crops. Chapter one is an introduction to high tunnels and production strategies. Chapter two discusses the results of the Montana High Tunnel Growers Survey, in which respondents reported that managing the high tunnel environment was their number one challenge. Two thirds of respondents produced crops during the shoulder seasons of spring and fall, a period of time when the climatic conditions are especially dynamic. Chapter three presents the findings on the influences various types of season extension have on light and temperature levels and the impacts they have on the accumulation of growing degree hours, soil degree hours, and daily light integral. While each layer retains heat, moderating the effect of low night air temperatures, it comes at the cost of lower light energy at the crop level. Heat retention performance of high tunnel plus row cover improves as outside air temperature decreases, maintaining crop level air temperature at -3°C despite an outside air temperature of -22°C. Chapter four presents the results of seeding date and row cover effects on the yield and days to harvest of six cool season crops. Row cover within the high tunnel only improved crop yields when outside air temperatures were well below the historical average. The early seeding date in the fall resulted in higher yields and fewer days to harvest, indicating that the two weeks difference between August 15th and August 30th has a large impact on production. Chapter five reports on the influence of low daily light integral has on the production of kale, lettuce, and spinach. While all three responded to increasing light, lettuce had the largest response with a 200% increase in dry weight when the daily light integral increased from 8 to 14 mol m -2 d -1.