Abstract
Onion ( Allium cepa L.) bulbs produced in the Pacific Northwest of the United States in 2014 and 2015 had unusually high incidence of internal decay. This decay was not detectable externally, leading to marketing problems when bulbs were packed and shipped to markets. The onion growing seasons in 2014 and 2015 were unusually hot, suggesting a connection of heat stress to bulb internal decay. Field studies to investigate the effect of temperature on onion bulb internal decay and yield were conducted in 2016–18 with drip-irrigated onions at the Oregon State University, Malheur Experiment Station located in eastern Oregon. Two long-day onion cultivars were submitted to four cultural practice variations to affect soil and bulb temperatures: bare soil check, supplemental heat using electric heat cables, white kaolinite clay application to the bulb sides and soil surface, and wheat ( Triticum aestivum L.) straw mulch. The treatments established significant midafternoon average bulb and soil surface temperature gradients in the following order of increasing temperature: straw mulch, kaolinite, check, and supplemental heat. Averaged over years and cultivars, straw-mulched onions had the highest yield of bulbs larger than 102 mm diameter. Averaged over years and cultivars, onions receiving supplemental heat had the lowest total and marketable yield with no difference among the other treatments. Straw mulched onions had higher total and marketable yield than the bare soil check treatment in 2017, the hottest year. Averaged over the 3 years and two cultivars, marketable yield and yield of bulbs larger than 102 mm diameter decreased with increasing midafternoon bulb temperatures. Kaolinite application did not increase bulb yield nor bulb size compared with the bare soil check. The incidence of internal bulb decay was low all 3 years. In 2017, onions receiving supplemental heat had the highest internal decay and the straw-mulched onions had among the lowest internal decay. There was little difference in the measured soil moisture among treatments. Straw mulching may attenuate the negative effects of excessive heat on yield and bulb internal quality for long day onion production.
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Claims 16
Claim · model-written summary
Treatments created significant increasing bulb and soil temperatures from straw mulch to kaolinite to check to supplemental heat.
- Taxon
- Onion
Allium cepat0 - Treatment
- treatmentse0
- Outcome
- bulb and soil surface temperature gradientse0
- Direction
- increasinge0
- Qualifier
- straw mulch, kaolinite, check, and supplemental heate0
- Comparator
- checke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The treatments established significant midafternoon average bulb and soil surface temperature gradients in the following order of increasing temperature: straw mulch, kaolinite, check, and supplemental heat”
t0“Onion”
Claim · model-written summary
Straw mulch produced the highest yield of onion bulbs larger than 102 mm.
- Taxon
- onionsAllium cepae0
- Treatment
- straw-mulchede0
- Outcome
- yield of bulbs larger than 102 mm diametere0
- Direction
- higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“straw-mulched onions had the highest yield of bulbs larger than 102 mm diameter”
Claim · model-written summary
Supplemental heat gave the lowest total onion yield.
- Taxon
- onionsAllium cepae0
- Treatment
- supplemental heate0
- Outcome
- totale0
- Direction
- loweste0
- Comparator
- other treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“onions receiving supplemental heat had the lowest total and marketable yield with no difference among the other treatments”
Claim · model-written summary
Supplemental heat gave the lowest marketable onion yield.
- Taxon
- onionsAllium cepae0
- Treatment
- supplemental heate0
- Outcome
- marketable yielde0
- Direction
- loweste0
- Comparator
- other treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“onions receiving supplemental heat had the lowest total and marketable yield with no difference among the other treatments”
Claim · model-written summary
Other treatments did not differ in total or marketable yield.
- Taxon
- onionsAllium cepae0
- Treatment
- other treatmentse0
- Outcome
- total and marketable yielde0
- Direction
- no differencee0
- Comparator
- other treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“onions receiving supplemental heat had the lowest total and marketable yield with no difference among the other treatments”
Claim · model-written summary
In the hottest year, straw mulch increased total onion yield over bare soil.
- Taxon
- onionsAllium cepae0
- Treatment
- Straw mulchede0
- Outcome
- totale0
- Direction
- highere0
- Qualifier
- 2017, the hottest yeare0
- Comparator
- bare soil check treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Straw mulched onions had higher total and marketable yield than the bare soil check treatment in 2017, the hottest year”
Claim · model-written summary
In the hottest year, straw mulch increased marketable onion yield over bare soil.
- Taxon
- onionsAllium cepae0
- Treatment
- Straw mulchede0
- Outcome
- marketable yielde0
- Direction
- highere0
- Qualifier
- 2017, the hottest yeare0
- Comparator
- bare soil check treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Straw mulched onions had higher total and marketable yield than the bare soil check treatment in 2017, the hottest year”
Claim · model-written summary
Marketable onion yield declined as midafternoon bulb temperatures increased.
- Taxon
- OnionAllium cepat0
- Treatment
- increasing midafternoon bulb temperaturese0
- Outcome
- marketable yielde0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“marketable yield and yield of bulbs larger than 102 mm diameter decreased with increasing midafternoon bulb temperatures”
t0“Onion”
Claim · model-written summary
Yield of onion bulbs over 102 mm declined as midafternoon bulb temperatures increased.
- Taxon
- OnionAllium cepat0
- Treatment
- increasing midafternoon bulb temperaturese0
- Outcome
- yield of bulbs larger than 102 mm diametere0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“marketable yield and yield of bulbs larger than 102 mm diameter decreased with increasing midafternoon bulb temperatures”
t0“Onion”
Claim · model-written summary
Kaolinite did not increase onion bulb yield compared with bare soil.
- Taxon
- OnionAllium cepat0
- Treatment
- Kaolinite applicatione0
- Outcome
- bulb yielde0
- Direction
- did not increasee0
- Comparator
- bare soil checke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Kaolinite application did not increase bulb yield nor bulb size compared with the bare soil check”
t0“Onion”
Claim · model-written summary
Kaolinite did not increase onion bulb size compared with bare soil.
- Taxon
- OnionAllium cepat0
- Treatment
- Kaolinite applicatione0
- Outcome
- bulb sizee0
- Direction
- did not increasee0
- Comparator
- bare soil checke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Kaolinite application did not increase bulb yield nor bulb size compared with the bare soil check”
t0“Onion”
Claim · model-written summary
Internal onion bulb decay was low in all three study years.
- Taxon
- OnionAllium cepat0
- Outcome
- incidence of internal bulb decaye0
- Direction
- lowe0
- Qualifier
- all 3 yearse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The incidence of internal bulb decay was low all 3 years”
t0“Onion”
Claim · model-written summary
In 2017 supplemental heat produced the highest internal onion decay.
- Taxon
- onionsAllium cepae0
- Treatment
- supplemental heate0
- Outcome
- internal decaye0
- Direction
- higheste0
- Qualifier
- 2017e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In 2017, onions receiving supplemental heat had the highest internal decay”
Claim · model-written summary
In 2017 straw mulch produced among the lowest internal onion decay.
- Taxon
- onionsAllium cepae0
- Treatment
- straw-mulchede0
- Outcome
- internal decaye0
- Direction
- loweste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the straw-mulched onions had among the lowest internal decay”
Claim · model-written summary
Measured soil moisture differed little among treatments.
- Taxon
- OnionAllium cepat0
- Treatment
- treatmentse0
- Outcome
- measured soil moisturee0
- Direction
- little differencee0
- Comparator
- treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was little difference in the measured soil moisture among treatments”
t0“Onion”
Claim · model-written summary
Straw mulching may reduce excessive heat damage to onion yield and internal quality.
- Taxon
- onionAllium cepae0
- Outcome
- Straw mulchinge0
- Qualifier
- may attenuate the negative effects of excessive heat on yield and bulb internal qualitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Straw mulching may attenuate the negative effects of excessive heat on yield and bulb internal quality for long day onion production”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.