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Seed shattering is a major problem in birdsfoot trefoil (Lotus corniculatus L.) seed production and limited information is available describing the effects of agronomic practices on shatter losses. The objectives of this research were to: (i) quantify the effects of soil-water availability on seed shatter and (ii) determine optimal harvest time on the basis of a heat unit method to minimize birdsfoot trefoil seed losses under western Oregon climatic conditions. Six treatments varying in water depletion percentage and replenishment amount were applied in 1994 and 1995 and two treatments in 1996 on a Woodburn silt loam soil (fine-silty, mixed, mesic Aquultic Argixeroll) near Corvallis, OR. The total amount of shattered seeds was correlated with total harvested seed yield (r = 0.93). Crop water stress index (CWSI) was inversely related to the percentage of seeds shattered (r = -0.76). Increasing amounts of applied water increased the potential of seed yield shattered (r = 0.65). Seed shatter losses fluctuated during the late-reproductive period, but were not influenced by irrigation or fluctuating climatic conditions. A total of 109 heat units (approximately 11 d), which were determined on the basis of a 10 ° C base temperature, were accumulated from the time of initial pod dehiscence until rapid seed shattering. The average seed yield losses due to shattering was 3 to 5.3 kg [ha.sup.-] [d.sup.-1]. The non-irrigated control treatment generally produced more seeds than irrigated treatments. It is, thus, best not to irrigate birdsfoot trefoil grown for seed in western Oregon because increasing amounts of irrigation water increased seed shattering., BIRDSFOOT TREFOIL is a perennial, non-bloating legume used for forage and hay production in the northeastern and midwestern USA as well as eastern Canada. Fairey (1994) identified some of the [...]

Forage legume seed crop responses to water stress differ for each species, so a single optimal water management strategy is not applicable. The objectives of this study were to determine the effects of irrigation timing and replenishment amount on birdsfoot trefoil (Lotus corniculatus L.) reproduction and seed yield in the Willamette Valley of western Oregon, USA. Six treatments varying in water depletion percentage and replenishment amount were applied in 1994 and 1995 on a Woodburn silt loam soil (fine-silty, mixed, mesic Aquultic Argix-eroll) near Corvallis. In 1996, only a low stress (LS) that met the weekly crop evapotranspirative demand and a non-irrigated control (C) treatment were investigated. In the first year of production, maintaining plants under low-stress conditions sustained flowering longer than with limited or no irrigation. Flowering was not affected by irrigation in the subsequent two production years. Total above-ground phytomass was correlated with the amount of irrigation water (r = 0.92). The C and all single application treatments had greater seed yields (SY) than the LS treatment in 1994. In 1995, all single application treatments had greater SY than the LS treatment. There was no difference between LS and C in 1995 and 1996. Umbel density and the number of seeds per pod were the primary determinants of total seed yield (r = 0.77 and 0.92, respectively). Optimal total seed production was achieved without supplemental irrigation under the humid temperate marine climatic conditions found in western Oregon., BIRDSFOOT TREFOIL is a perennial, non-bloating forage legume used for pasture, hay, and silage in the midwestern and northeastern USA and eastern Canada. Annual U.S. certified seed production is estimated [...]

Forage legume seed crop reproduction can be modified by regulating soil-water availability. However, responses to water stress differ for each species, so a single optimal water management strategy is not available for all crops. The objectives of this research were to determine the crop-water requirements and the optimal water management conditions for birdsfoot trefoil (Lotus corniculatus L.) when grown for seed production under humid temperate marine climatic conditions of western Oregon, USA. The experiment was conducted on a Woodburn silt loam soil (fine-silty, mixed, mesic Aquultic Argixeroll) near Corvallis. Four single-application treatments varying in water depletion percentage (30 and 60% of field capacity) and replenishment amount (50 and 100% of amount depleted) were applied in 1994 and 1995. A low-stress treatment (LS) that received two to three applications per week of the amount depleted since the last application and a non-irrigated control were also investigated in 1994, 1995, and 1996. Increasing amounts of applied water resulted in increased seasonal crop evapotranspiration ([ET.sub.c]) with plants grown under lowstress having the greatest [ET.sub.c] and non-irrigated control plants the least (r = 0.91). The fraction of available soil water used by non-irrigated plants was greatest and the LS treatment the least of all treatments. For non-irrigated conditions, the crop-water requirement ranged from 240 to 255 mm. Soil-water conditions favorable for high vegetative development were opposite of the conditions for optimal seed yield water-use efficiency. Unlike other forage legume seed crops, birdsfoot trefoil grown under these conditions required minimal or no supplemental irrigation to achieve maximal seed yield., Birdsfoot trefoil is a perennial forage legume used for hay, pasture, and silage in the midwestern and northeastern USA and eastern Canada. It is adapted to a wide range of [...]