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
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33811 |
| Date | 13 June 1997 |
| Creators | Garc��a-D��az, Carlos Alberto |
| Contributors | Steiner, Jeffrey J. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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