Abstract
Date palm (Phoenix dactylifera L.) production relies on the availability of viable and physiologically active pollen during female flowering, making pollen storage an important strategy to overcome flowering asynchrony and ensure effective artificial pollination. In this study, we systematically reviewed and quantitatively synthesized the effects of pollen storage conditions on pollen physiological quality and reproductive performance in date palm. Following PRISMA guidelines, 22 experimental studies were identified in the qualitative synthesis, and comparable quantitative datasets were used for meta-analysis. Acetocarmine staining, the most commonly used method for assessing pollen stainability across studies, was selected as the standardized indicator of pollen stainability. Multilevel random-effects meta-regression models were applied to evaluate temporal deterioration patterns over storage periods of up to 24 months, while standardized forest plot meta-analyses were used to estimate pooled effects after 12 months of storage. The results revealed a strong temperature-dependent decline in pollen physiological quality. Acetocarmine stainability declined by −6.41, −3.10, −2.62, and −2.24% month−1 under ambient, refrigerated, mild freezing, and moderate freezing conditions, respectively, whereas germination declined by −6.77, −1.86, −3.14, −1.09, and −1.05% month−1 under ambient (23–25 °C), refrigerated (4–5 °C), mild freezing (−5 °C), moderate freezing (−20 °C), and deep freezing (−80 °C) conditions, respectively. After 12 months of storage, stainability, germination, and fruit set were significantly reduced relative to fresh pollen. In contrast, pollen storage had no significant effect on final fruit weight, suggesting that pollen deterioration primarily affects fertilization success rather than subsequent fruit development. The available evidence suggests that low-temperature storage represents the most effective strategy for preserving date palm pollen functionality. Refrigerated storage around 4 °C appears to provide a reliable and accessible option for short- to medium-term pollen preservation, whereas freezing conditions may be advantageous for longer storage periods when moisture control and thawing procedures are properly managed.
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Claims 14
Claim · model-written summary
Acetocarmine pollen stainability in date palm declined by −6.41% per month under ambient storage.
- Taxon
- Phoenix dactylifera L.
Phoenix dactyliferat0 - Treatment
- ambiente0
- Outcome
- Acetocarmine stainabilitye0
- Direction
- declinede0
- Value
- −6.41e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Acetocarmine stainability declined by −6.41, −3.10, −2.62, and −2.24% month−1 under ambient, refrigerated, mild freezing, and moderate freezing conditions, respectively”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Acetocarmine pollen stainability in date palm declined by −3.10% per month under refrigerated storage.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- refrigeratede0
- Outcome
- Acetocarmine stainabilitye0
- Direction
- declinede0
- Value
- −3.10e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Acetocarmine stainability declined by −6.41, −3.10, −2.62, and −2.24% month−1 under ambient, refrigerated, mild freezing, and moderate freezing conditions, respectively”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Acetocarmine pollen stainability in date palm declined by −2.62% per month under mild freezing storage.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- mild freezinge0
- Outcome
- Acetocarmine stainabilitye0
- Direction
- declinede0
- Value
- −2.62e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Acetocarmine stainability declined by −6.41, −3.10, −2.62, and −2.24% month−1 under ambient, refrigerated, mild freezing, and moderate freezing conditions, respectively”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Acetocarmine pollen stainability in date palm declined by −2.24% per month under moderate freezing storage.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- moderate freezinge0
- Outcome
- Acetocarmine stainabilitye0
- Direction
- declinede0
- Value
- −2.24e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Acetocarmine stainability declined by −6.41, −3.10, −2.62, and −2.24% month−1 under ambient, refrigerated, mild freezing, and moderate freezing conditions, respectively”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Pollen germination in date palm declined by −6.77% per month under ambient (23–25 °C) storage.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- ambient (23–25 °C)e0
- Outcome
- germinatione0
- Direction
- declinede0
- Value
- −6.77e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“germination declined by −6.77, −1.86, −3.14, −1.09, and −1.05% month−1 under ambient (23–25 °C), refrigerated (4–5 °C), mild freezing (−5 °C), moderate freezing (−20 °C), and deep freezing (−80 °C) conditions, respectively”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Pollen germination in date palm declined by −1.86% per month under refrigerated (4–5 °C) storage.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- refrigerated (4–5 °C)e0
- Outcome
- germinatione0
- Direction
- declinede0
- Value
- −1.86e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“germination declined by −6.77, −1.86, −3.14, −1.09, and −1.05% month−1 under ambient (23–25 °C), refrigerated (4–5 °C), mild freezing (−5 °C), moderate freezing (−20 °C), and deep freezing (−80 °C) conditions, respectively”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Pollen germination in date palm declined by −3.14% per month under mild freezing (−5 °C) storage.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- mild freezing (−5 °C)e0
- Outcome
- germinatione0
- Direction
- declinede0
- Value
- −3.14e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“germination declined by −6.77, −1.86, −3.14, −1.09, and −1.05% month−1 under ambient (23–25 °C), refrigerated (4–5 °C), mild freezing (−5 °C), moderate freezing (−20 °C), and deep freezing (−80 °C) conditions, respectively”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Pollen germination in date palm declined by −1.09% per month under moderate freezing (−20 °C) storage.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- moderate freezing (−20 °C)e0
- Outcome
- germinatione0
- Direction
- declinede0
- Value
- −1.09e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“germination declined by −6.77, −1.86, −3.14, −1.09, and −1.05% month−1 under ambient (23–25 °C), refrigerated (4–5 °C), mild freezing (−5 °C), moderate freezing (−20 °C), and deep freezing (−80 °C) conditions, respectively”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Pollen germination in date palm declined by −1.05% per month under deep freezing (−80 °C) storage.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- deep freezing (−80 °C)e0
- Outcome
- germinatione0
- Direction
- declinede0
- Value
- −1.05e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“germination declined by −6.77, −1.86, −3.14, −1.09, and −1.05% month−1 under ambient (23–25 °C), refrigerated (4–5 °C), mild freezing (−5 °C), moderate freezing (−20 °C), and deep freezing (−80 °C) conditions, respectively”
t0“Phoenix dactylifera L.”
Claim · model-written summary
After 12 months of storage, pollen stainability, germination and fruit set were significantly reduced relative to fresh pollen.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- 12 months of storagee0
- Outcome
- stainability, germination, and fruit sete0
- Direction
- reducede0
- Comparator
- fresh pollene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After 12 months of storage, stainability, germination, and fruit set were significantly reduced relative to fresh pollen”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Pollen storage had no significant effect on final fruit weight.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- pollen storagee0
- Outcome
- final fruit weighte0
- Direction
- no_changeinferrede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“pollen storage had no significant effect on final fruit weight”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Low-temperature storage represents the most effective strategy for preserving date palm pollen functionality.
- Taxon
- date palmPhoenix dactyliferae0
- Treatment
- low-temperature storagee0
- Outcome
- preserving date palm pollen functionalitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“low-temperature storage represents the most effective strategy for preserving date palm pollen functionality”
Claim · model-written summary
Refrigerated storage around 4 °C appears a reliable and accessible option for short- to medium-term pollen preservation.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- Refrigerated storage around 4 °Ce0
- Outcome
- short- to medium-term pollen preservatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Refrigerated storage around 4 °C appears to provide a reliable and accessible option for short- to medium-term pollen preservation”
t0“Phoenix dactylifera L.”
Claim · model-written summary
Freezing conditions may be advantageous for longer pollen storage periods when moisture control and thawing are properly managed.
- Taxon
- Phoenix dactylifera L.Phoenix dactyliferat0
- Treatment
- freezing conditionse0
- Outcome
- longer storage periodse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“freezing conditions may be advantageous for longer storage periods when moisture control and thawing procedures are properly managed”
t0“Phoenix dactylifera L.”
The same questions in other papers
cold · growth · Phoenix dactylifera (date palm)Positive and negative results
7 in the opposite direction
- positive
- positive
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4 papers more in this group
See all 8 papers →storage · yield · Phoenix dactylifera (date palm)Results agree
2 papers in the same direction as this paper
- negative
- negative
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.