Excessive growth by red clover, Trifolium pratense L., grown for seed
interferes with maximum seed production and harvest in Oregon's Willamette Valley.
This study was conducted during 1986 and 1987 on red clover cv. Kenland to
determine if plant height and dry matter production could be inhibited and seed yields
improved with the plant growth regulators (PGRs) uniconazol (XE-1019) and
paclobutrazol (Parlay). The effects of different soil-applied and foliar-applied PGRs
and application rates on plant height, crop biomass, and yield components of red clover
were measured at Corvallis, OR on Woodburn silt-loam (fine-silty mixed mesic
Aquultic Argixerolls) soil. Soil-applied PGRs were also managed under single and
multiple irrigation regimes in 1986.
Under a single irrigation regime in 1986, canopy height was reduced by 32%
when XE-1019 was applied at 1.12 kg ai/ha and was reduced by 13% when Parlay was
applied at 1.68 kg ai/ha. Averaged over the two-year period, straw yield was reduced
40% with XE-1019 (1.12 kg ai/ha) and by 12% with Parlay (1.68 kg ai/ha). Seed
yield was increased by 11% with the lower XE-1019 rate (0.14 kg ai/ha) and was
increased by 14% with the higher Parlay rate (1.68 kg ai/ha). Soil-applied PGR
treatments reduced canopy height by 25% with XE-1019 (1.12 kg ai/ha) and was
reduced by 11% with Parlay (1.68 kg ai/ha) under multiple irrigation in 1986. Straw
yield was reduced by 30% with XE-1019 (0.84 kg ai/ha), but Parlay had no effect on
straw yield. In addition, seed yield was increased by 8% with XE-1019 (0.56 kg ai/ha)
and by 18% with Parlay (1.68 kg ai/ha).
Foliar-applied XE-1019 (1.12 kg ai/ha) reduced canopy height by 13% in 1986
and by 25% in 1987, whereas foliar-applied Parlay (1.12 kg ai/ha) reduced canopy
height by 9% in 1986 and by 19% in 1987. In 1986, seed yield increases averaged
16% across all 3CE-1019 treatments (0.07 to 1.12 kg ai/ha) and was increased an
average of 21% across all Parlay treatments (0.28 to 1.68 kg ai/ha). However, 1987
was drier and warmer than 1986, consequently, foliar-applied XE-1019 reduced seed
yields by an average of 23% and Parlay reduced seed yields by an average of 21%.
Total dry weight and straw weight were unaffected by foliar-applied PGR treatment in
both years.
Use of XE-1019 and Parlay in field crop production has the potential to reduce
dry matter production and improve seed recovery, but results vary from year to year.
These PGRs have the potential to improve seed yields and may be effective in
improving harvest conditions by reducing vegetative biomass. / Graduation date: 1995
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37562 |
| Date | 10 June 1994 |
| Creators | Silberstein, Thomas B. |
| Contributors | Chastain, Thomas G., Young, William C. III |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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