Abstract
Background: Intercropping tobacco with soybean is a sustainable approach to improve resource use efficiency and crop resilience. However, the optimal soybean planting density for maximizing the physiological and protective benefits to tobacco remains unclear. Methods: A field experiment was conducted in Yunnan Province, China, including five treatments: tobacco monoculture and four tobacco-soybean intercropping densities. Photosynthetic parameters, carbon and nitrogen metabolism, defense-related physiology, and leaf chemical composition were measured across key growth stages. Results: Intercropping density significantly affected photosynthetic and metabolic performance in both species. The medium density with four soybean holes achieved the best results, increasing the net photosynthetic rate of tobacco by 30.8% compared with monoculture during the vigorous growth stage. This treatment also enhanced PSII photochemical efficiency, with Fv/Fm and ΦPSII values both higher than other treatments, and chlorophyll a content increased by 32.9% compared with high-density intercropping. The activities of Rubisco and nitrate reductase rose by 18.8% and 49.2%, respectively. At the same time, this density reduced the incidence of tobacco black shank disease and increased salicylic acid and jasmonic acid contents by 38.9% and 33.7%. Peroxidase, superoxide dismutase, and phenylalanine ammonia-lyase activities were also elevated. Tobacco leaves under this treatment showed a balanced chemical composition with high sugar, high potassium, and low chlorine contents, resulting in superior flue-cured quality and the highest economic return. Conclusion: The four-hole soybean density optimized photosynthesis, nitrogen metabolism, and defense responses, improving tobacco quality and yield. These findings provide a physiological and agronomic basis for developing efficient and sustainable tobacco-soybean intercropping systems.
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Claims 11
Claim · model-written summary
Four soybean holes increased tobacco net photosynthetic rate by 30.8% against monoculture.
- Taxon
- tobacco
Nicotiana tabacume0 - Organ / stage
- vigorous growth stagee0
- Treatment
- four soybean holese0
- Outcome
- net photosynthetic ratee0
- Direction
- increasinge0
- Value
- 30.8%e0
- Comparator
- monoculturee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The medium density with four soybean holes achieved the best results, increasing the net photosynthetic rate of tobacco by 30.8% compared with monoculture during the vigorous growth stage”
Claim · model-written summary
Four-hole density raised Fv/Fm and ΦPSII above other treatments.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- four soybean holest1
- Outcome
- Fv/Fm and ΦPSII valuese0
- Direction
- highere0
- Comparator
- other treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This treatment also enhanced PSII photochemical efficiency, with Fv/Fm and ΦPSII values both higher than other treatments”
t0“tobacco”
t1“four soybean holes”
Claim · model-written summary
Chlorophyll a rose 32.9% against high-density intercropping.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- four soybean holest1
- Outcome
- chlorophyll a contente0
- Direction
- increasede0
- Value
- 32.9%e0
- Comparator
- high-density intercroppinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“chlorophyll a content increased by 32.9% compared with high-density intercropping”
t0“tobacco”
t1“four soybean holes”
Claim · model-written summary
Rubisco activity rose by 18.8%.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- four soybean holest1
- Gene
- Rubiscoe0
- Outcome
- activities of Rubiscoe0
- Direction
- rosee0
- Value
- 18.8%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The activities of Rubisco and nitrate reductase rose by 18.8% and 49.2%, respectively”
t0“tobacco”
t1“four soybean holes”
Claim · model-written summary
Nitrate reductase activity rose by 49.2%.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- four soybean holest1
- Gene
- nitrate reductasee0
- Outcome
- nitrate reductasee0
- Direction
- rosee0
- Value
- 49.2%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The activities of Rubisco and nitrate reductase rose by 18.8% and 49.2%, respectively”
t0“tobacco”
t1“four soybean holes”
Claim · model-written summary
Four-hole density reduced tobacco black shank incidence.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- four soybean holest1
- Outcome
- incidence of tobacco black shank diseasee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this density reduced the incidence of tobacco black shank disease”
t0“tobacco”
t1“four soybean holes”
Claim · model-written summary
Salicylic acid content increased by 38.9%.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- four soybean holest1
- Outcome
- salicylic acide0
- Direction
- increasede0
- Value
- 38.9%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased salicylic acid and jasmonic acid contents by 38.9% and 33.7%”
t0“tobacco”
t1“four soybean holes”
Claim · model-written summary
Jasmonic acid content increased by 33.7%.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- four soybean holest1
- Outcome
- jasmonic acide0
- Direction
- increasede0
- Value
- 33.7%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased salicylic acid and jasmonic acid contents by 38.9% and 33.7%”
t0“tobacco”
t1“four soybean holes”
Claim · model-written summary
Peroxidase, superoxide dismutase and phenylalanine ammonia-lyase activities were elevated.
- Taxon
- tobaccoNicotiana tabacumt0
- Treatment
- four soybean holest1
- Outcome
- Peroxidase, superoxide dismutase, and phenylalanine ammonia-lyase activitiese0
- Direction
- elevatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Peroxidase, superoxide dismutase, and phenylalanine ammonia-lyase activities were also elevated”
t0“tobacco”
t1“four soybean holes”
Claim · model-written summary
Leaves under four-hole density had high sugar and potassium and low chlorine content.
- Taxon
- TobaccoNicotiana tabacume0
- Organ / stage
- leavese0
- Outcome
- balanced chemical compositione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tobacco leaves under this treatment showed a balanced chemical composition with high sugar, high potassium, and low chlorine contents”
Claim · model-written summary
Four-hole density yielded superior flue-cured quality and highest economic return.
- Taxon
- tobaccoNicotiana tabacumt0
- Outcome
- superior flue-cured quality and the highest economic returne0
- Direction
- superiore0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“resulting in superior flue-cured quality and the highest economic return”
t0“tobacco”
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1 paper in the same direction as this paper
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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.