There is no information available on water management of birdsfoot trefoil grown for seed. Information is also not available describing how to minimize seed losses due to shattering in order to obtain consistently high birdsfoot trefoil seed yields. The objectives of this research are to: (i) quantify crop water use, effects of soil-water availability and optimal water management conditions for birdsfoot trefoil grown for seed, (ii) determine the effects of irrigation timing and amount on flower production, seed yield, and yield components, and (iii) quantify the effects of soil-water availability on seed shattering and determine optimal harvest time to reduce seed yield losses due to shattering. Five supplemental irrigations treatments and a non-irrigated control were applied in 1994 and 1995; in 1996, only treatments low stress and non irrigated control were investigated, near Corvallis, OR on a Woodburn silt loam soil (fine-silty, mixed, mesic Aquultic Argixeroll). Increasing amounts of applied water increased seasonal ET[subscript c] with low stressed plants having the greatest ET[subscript c] and non-irrigated control plants the least. The fraction of available soil-water used was primarily dependent upon the irrigation depletion percentage and secondarily dependent upon irrigation replacement amount. Soil-water conditions favorable for vegetative development and seed yield water use efficiency are opposite. Birdsfoot trefoil grown for seed requires minimal or no supplemental irrigation. For non-irrigated conditions, the crop water requirement ranges from 240 to 255 mm. In the first year of production, plants under low-stress conditions sustained flowering longer than with limited or no irrigation applications. Flowering was not affected by irrigation in subsequent years of production. Total above-ground phytomass production was correlated with the amount of applied irrigation water (r=0.92). Umbel density and number of seeds per pod are the primary determinants of total seed yield (r=0.77 and 0.92, respectively). Manipulation of the reproductive development pattern by different water application times and amounts does not affect peak seed shattering events. Crop-water stress status affects the percentage of total shattered seeds shattered at harvest time (r=-0.76). Increasing amounts of applied water increase the percentage of potential shatter losses that will shatter by harvest time (r=0.65). Seed shatter losses fluctuate during the reproductive development period but are not influenced by the water application treatments. Climatic variables as measured in this experiment cannot be used to predict the time of peak seed shatter events. A total of 109 heat units are needed from the time from initial pod dehiscence until rapid shattering occurs. / Graduation date: 1998

Birdsfoot trefoil (Lotus corniculatus L.) is a popular perennial, non-bloating forage legume used for pasture, hay and silage throughout the temperate regions of Europe, Asia Minor, North Africa and North and South America. It is regarded as the most morphologically and biochemically variable species in the genus. Research investigating the relationships of morphological, ecological and genetic characteristics describing birdsfoot trefoil germplasm has not been done. This research was conducted to investigate if the geographic and ecological origins of birdsfoot trefoil genotypes are related to differences in: (i) crossing compatibility among diverse genotypes, (ii) morphological traits, (iii) PCR-RAPD banding patterns, and (iv) temperature response of chlorophyll Photosystem II variable fluorescence. The 28 genotypes were classified by morphological characteristics, 130 polymorphic random amplified polymorphic DNA bands, and eight ecological characteristics of the original collection sites. The ease of introgressing 27 exotic genotypes into other germplasm backgrounds was determined by using bidirectional crosses with a domestic and exotic genotype tester. The chlorophyll fluorescence transients ratios (FTR) were determined from eight genotypes that were selected by their ecological diversity with measurements made from 10 to 40��C in 5��C increments for 33 minutes from the time of initial dark adaptation in 3 minute increments. Morphological similarities among genotypes were related to the general geographic proximities of their collection sites and their genetic similarity based on RAPD markers. Utilizing genetic, morphological and ecological descriptions revealed combinations of variation among genotypes that would not be observed with single measurements. Incompatibility among crosses was expressed as either an inability of plants to set pods or F��� progeny resulting from crosses producing inviable pollen. Reproductive barriers were environmentally neutral and randomly distributed through the among the genotypes. Intermediate crosses could be identified to bridge any combination of genotypes that were incompatible. The eight genotypes differed in their FTR responses and were grouped into two classes. However, no associations were found between genotype similarities by FTR with genetic or ecologic similarities. / Graduation date: 1998

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1955. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 135-139).

Thesis--Wisconsin. / Includes bibliographical references (leaves 23-24).

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Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 174-183). Also available on the Internet.