Abstract
BACKGROUND AND AIMS: Evergreen conifer shoots that develop under full sunlight eventually move to the shade within the canopy as the tree grows. We hypothesized that densely packed needles develop shade characteristics even under full sunlight due to mutual shading, allowing them to survive longer in the canopy shade. METHODS: To test this hypothesis, we measured photosynthetic light responses at the shoot and needle levels in four species: Picea glehnii (shade-intolerant), P. jezoensis (intermediate shade-tolerant), Abies sachalinensis (shade-tolerant) and Taxus cuspidata (highly shade-tolerant), grown under open (100 % sunlight) and shade (10 % sunlight) conditions. KEY RESULTS: In P. glehnii, P. jezoensis and A. sachalinensis, needle-level photosynthetic and morphological traits showed minimal differences between light conditions, indicating the development of shade-characteristic needles even under full sunlight. In contrast, open-grown needles of T. cuspidata exhibited sun-acclimated traits, including higher photosynthetic capacity and thicker mesophyll tissue than shade-grown counterparts. Shoot-level photosynthetic capacity was higher in more shade-intolerant species with denser needle packing, and in open-grown seedlings across species. CONCLUSIONS: Shoot-level acclimation to light environments in P. glehnii, P. jezoensis and A. sachalinensis was governed primarily by needle configuration. In T. cuspidata, it was influenced by both needle-level photosynthesis and shoot morphology. The presence of shade-characteristic needles along with reduced needle packing from age-related stem thickening may contribute to the longevity of evergreen conifer shoots under canopy shading.
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Claims 6
Claim · model-written summary
In P. glehnii, P. jezoensis and A. sachalinensis needle-level photosynthetic and morphological traits differed minimally between open and shade light.
- Taxon
- P. glehnii, P. jezoensis and A. sachalinensis
Picea jezoensis
Abies sachalinensis
Picea glehniie0 - Treatment
- light conditionse0
- Outcome
- needle-level photosynthetic and morphological traitse0
- Direction
- minimal differencese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In P. glehnii, P. jezoensis and A. sachalinensis, needle-level photosynthetic and morphological traits showed minimal differences between light conditions”
Claim · model-written summary
Open-grown T. cuspidata needles had higher photosynthetic capacity and thicker mesophyll tissue than shade-grown ones.
- Taxon
- T. cuspidata
Taxus cuspidatae0 - Organ / stage
- needlese0
- Treatment
- open-growne0
- Outcome
- higher photosynthetic capacity and thicker mesophyll tissuee0
- Direction
- highere0
- Comparator
- shade-grown counterpartse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“open-grown needles of T. cuspidata exhibited sun-acclimated traits, including higher photosynthetic capacity and thicker mesophyll tissue than shade-grown counterparts”
Claim · model-written summary
Shoot-level photosynthetic capacity was higher in more shade-intolerant conifer species with denser needle packing.
Verbatim
e0“Shoot-level photosynthetic capacity was higher in more shade-intolerant species with denser needle packing, and in open-grown seedlings across species”
t0“evergreen conifers”
Claim · model-written summary
Shoot-level photosynthetic capacity was higher in open-grown seedlings across species.
- Taxon
- evergreen coniferst0
- Organ / stage
- seedlingse0
- Treatment
- open-growne0
- Outcome
- Shoot-level photosynthetic capacitye0
- Direction
- highere0
Not reportedComparator
Verbatim
e0“Shoot-level photosynthetic capacity was higher in more shade-intolerant species with denser needle packing, and in open-grown seedlings across species”
t0“evergreen conifers”
Claim · model-written summary
Shoot-level light acclimation in P. glehnii, P. jezoensis and A. sachalinensis was governed mainly by needle configuration.
- Taxon
- P. glehnii, P. jezoensis and A. sachalinensisPicea jezoensisAbies sachalinensisPicea glehniie0
- Outcome
- Shoot-level acclimation to light environmentse0
- Qualifier
- needle configuratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot-level acclimation to light environments in P. glehnii, P. jezoensis and A. sachalinensis was governed primarily by needle configuration”
Claim · model-written summary
In T. cuspidata, shoot-level acclimation was influenced by both needle-level photosynthesis and shoot morphology.
- Taxon
- T. cuspidataTaxus cuspidatae0
- Outcome
- influenced by both needle-level photosynthesis and shoot morphologye0
- Qualifier
- needle-level photosynthesis and shoot morphologye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In T. cuspidata, it was influenced by both needle-level photosynthesis and shoot morphology”