Theses and Dissertations at Montana State University (MSU)
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Item Photoperiodic responses of Cannabis sativa: developmental and molecular aspects(Montana State University - Bozeman, College of Agriculture, 2022) Avci, Burak; Chairperson, Graduate Committee: Jennifer A. LachowiecThe timing of reproductive development is influenced by photoperiod (daylength) in many plants, including Cannabis sativa. However, the developmental and molecular details and the variability of photoperiodic responses in C. sativa are not well understood. I evaluated the photoperiod sensitivity of four high-CBD drug-type Cannabis varieties for four stages of reproductive development by comparing the timing of each stage between plants that received different periods of long-day (LD) exposure prior to the short-day (SD) treatment. In addition, I looked at the influence of photoperiod on the duration between different stages of development, and the effect of plant age on photoperiod sensitivity. The timing of each stage, including the induction of solitary flowers and anthesis was accelerated in 'Eden' under SD conditions. 'Grape Indica' started developing inflorescences in 6 weeks under LD, but the process was also faster when SD treatment began earlier. The development of 'Auto Pivot', on the other hand, was slightly delayed under SD, but each stage occurred with a consistent number of leaves in all treatments. 'Russian Auto' had a shorter juvenile phase and showed accelerated inflorescence development under SD, but earlier stages were not accelerated even though SD development happened with fewer leaves at each stage. Also, older plants responded to SD slightly earlier, especially compared to plants directly started in SD. These results suggest there are important differences between C. sativa varieties in terms of the timing and the process of reproductive development, even within the day-neutral/auto-flowering varieties. I identified four FLOWERING LOCUS T (FT)-LIKE genes in the Cannabis genome and analyzed their diurnal expression patterns in 'Eden' and 'Auto Pivot' under LD and SD. FTL2 showed a similar expression pattern to FT genes that are known to induce flowering in other SD species, and the expression in photoperiod-sensitive variety, Eden, was different between photo-period treatments, while it was mostly unaffected in the day-neutral variety, Auto Pivot, suggesting FTL2 could be a potential photoperiod-regulated floral promoter in C. sativa.Item Starch utilization, root bud correlative inhibition, and endogenous indole-3-acetic acid levels in leafy spurge (Euphorbia esula L.)(Montana State University - Bozeman, College of Agriculture, 1986) Nissen, Scott Jay; Chairperson, Graduate Committee: Michael Foley.Leafy spurge (Euphorbia esula L.) is a rapidly spreading perennial rangeland weed which continues to persist and spread despite increased efforts at biological and chemical control. The persistence of leafy spurge can be traced directly to the plant’s root carbohydrate reserves and its effective means of vegetative reproduction. Research was initiated to examine aspects of these two important survival mechanisms . Utilization of leaf, stem, root and latex starch was monitored in leafy spurge plants during a 52 day light starvation period. Leaf, stem and root starch levels decreased rapidly in light starved plants; however, detectable levels of starch were present even after 52 days without light. Latex starch levels did not change significantly. Amylase activity was present in the latex; however, latex starch granules were found to be resistant to enzymatic hydrolysis. Results indicated that latex starch granules do not function as a source of utilizable carbohydrate. Root buds were found to be quiescent during most of the growing season due to correlative inhibition rather than innate dormancy. Innate dormancy occurred when plants were in full flower; however, elongation could be stimulated by chilling intact plants for 8 days at 4 C. Exogenous applications of indole-3-acetic acid and napthalene-acetic acid at concentrations of 10 -3 M and 10 -5 M respectively, completely inhibited elongation of excised root buds. Significant increases in root bud elongation were produced by 1 mM 2,3,5-tri-iodobenzoic acid applied to stem and root tissue. These data provide evidence for the involvement of IAA in correlative control of root bud growth. Primary root and root bud endogenous IAA levels were determined at three phenologic stages: vegetative, full flower and post flower. Free IAA levels were highest in root bud of full flowering plants which were found in previous studies to have a diminished capacity to elongate. Levels of conjugated IAA increased during phenologic development. Primary root free IAA levels did not appear related to lowered root bud elongation during full flower.Item Initiation of the reproductive stage in wheats varying in winterhardiness(Montana State University - Bozeman, College of Agriculture, 1985) Chaudhry, Sadiq HussainItem Reproduction and genetics of sainfoin (Onobrychis viciaefolia Scop.) as they relate to its breeding(Montana State University - Bozeman, College of Agriculture, 1972) Knipe, William JayItem Morphological, genetic and molecular analysis of the mating process in Ustilago hordei(Montana State University - Bozeman, College of Agriculture, 1993) Martinez-Espinoza, Alfredo DickItem Life history and reproductive strategies in Artemisia(Montana State University - Bozeman, College of Agriculture, 1981) Harvey, Stephen John