Abstract
Agricultural communities in the semiarid regions of the world are constantly being affected by water scarcity, increased regulations restricting water use, strong competition for irrigation water with the urban sector, and severe drought periods. Conversely, the consumer demand for high-quality and nutritious foods is increasing rapidly. A 2-year field study evaluated growth, yield, and bulb quality in response to precision planting density and deficit irrigation of onion ( Allium cepa L.) in southwest Texas. Seeds of short-day sweet onion cv. Texas Grano 1015Y were planted in the field on 11 Nov. 2007 and 30 Oct. 2008 at two planting densities (PDs), 397,000 (standard) and 484,000 (high) seeds/ha. Three irrigation rates using growth stage-specific crop coefficients and subsurface drip were imposed after plants were fully established, 100%, 75%, and 50% crop evapotranspiration rates (ETc). Total rainfall plus irrigation received for each irrigation rate were 594, 501, and 413 mm in 2008 and 662, 574, and 486 mm in 2009. In both seasons, there were consistent trends in growth, yield, and quality parameters. Leaf fresh weight was unaffected by PD but was reduced by deficit irrigation at 50% ETc. Although increasing planting density reduced the average bulb size by 12%, it increased the number of marketable bulbs by 21% to 33% and marketable yield by 7% to 14%. In contrast, deficit irrigation showed a trend to reduce both the number of bulbs and bulb size with yield reductions of 8% to 13% at 75% ETc and 19% to 27% at 50% ETc. Neither planting density nor deficit irrigation rate had a significant effect on soluble solids content, pungency, or quercetin contents. These results suggest that growers of short-day onions in semiarid regions could adjust PDs to target high-value bulb sizes. Implementing water-conserving practices (deficit irrigation at 75% ETc rate) would result in a decrease of high-value bulb grades and modest losses in yield but not flavor or nutritional components.
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Claims 11
Claim · model-written summary
Planting density did not significantly affect leaf fresh weight.
- Taxon
- Onion
Allium cepat0 - Treatment
- PDe0
- Outcome
- Leaf fresh weighte0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf fresh weight was unaffected by PD but was reduced by deficit irrigation at 50% ETc.”
t0“Onion”
Claim · model-written summary
Deficit irrigation at 50% ETc reduced leaf fresh weight.
- Taxon
- OnionAllium cepat0
- Treatment
- deficit irrigation at 50% ETce0
- Outcome
- Leaf fresh weighte0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf fresh weight was unaffected by PD but was reduced by deficit irrigation at 50% ETc.”
t0“Onion”
Claim · model-written summary
Higher planting density reduced average bulb size by 12%.
- Taxon
- OnionAllium cepat0
- Treatment
- increasing planting densitye0
- Outcome
- average bulb sizee0
- Direction
- reducede0
- Value
- 12%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increasing planting density reduced the average bulb size by 12%”
t0“Onion”
Claim · model-written summary
Higher planting density increased marketable bulb number by 21% to 33%.
- Taxon
- OnionAllium cepat0
- Outcome
- number of marketable bulbse0
- Direction
- increasede0
- Value
- 21% to 33%e0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it increased the number of marketable bulbs by 21% to 33%”
t0“Onion”
Claim · model-written summary
Higher planting density increased marketable yield by 7% to 14%.
- Taxon
- OnionAllium cepat0
- Outcome
- marketable yielde0
- Direction
- increasede0
- Value
- 7% to 14%e0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it increased the number of marketable bulbs by 21% to 33% and marketable yield by 7% to 14%”
t0“Onion”
Claim · model-written summary
Deficit irrigation tended to reduce bulb number and bulb size.
- Taxon
- OnionAllium cepat0
- Treatment
- deficit irrigatione0
- Outcome
- number of bulbs and bulb sizee0
- Direction
- reducee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“deficit irrigation showed a trend to reduce both the number of bulbs and bulb size”
t0“Onion”
Claim · model-written summary
At 75% ETc, yield fell by 8% to 13%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“yield reductions of 8% to 13% at 75% ETc”
t0“Onion”
Claim · model-written summary
At 50% ETc, yield fell by 19% to 27%.
- Taxon
- OnionAllium cepat0
- Treatment
- 50% ETce0
- Value
- 19% to 27%e0
Not reportedComparatorOutcomeDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“19% to 27% at 50% ETc”
t0“Onion”
Claim · model-written summary
Planting density and deficit irrigation had no significant effect on soluble solids, pungency or quercetin.
- Taxon
- OnionAllium cepat0
- Treatment
- planting densitye0
- Outcome
- soluble solids content, pungency, or quercetin contentse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither planting density nor deficit irrigation rate had a significant effect on soluble solids content, pungency, or quercetin contents.”
t0“Onion”
Claim · model-written summary
Growers could adjust planting densities to target high-value bulb sizes.
- Taxon
- OnionAllium cepat0
- Outcome
- adjust PDs to target high-value bulb sizese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“growers of short-day onions in semiarid regions could adjust PDs to target high-value bulb sizes”
t0“Onion”
Claim · model-written summary
The authors suggest 75% ETc irrigation would reduce high-value grades and modestly reduce yield while preserving flavor and nutrition.
- Taxon
- OnionAllium cepat0
- Outcome
- deficit irrigation at 75% ETc ratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“deficit irrigation at 75% ETc rate) would result in a decrease of high-value bulb grades and modest losses in yield but not flavor or nutritional components”
t0“Onion”
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