Abstract
Biostimulants are substances able to improve water and nutrient use efficiency and counteract stress factors by enhancing primary and secondary metabolism. Premise of the work was to exploit raw extracts from leaves (LE) or flowers (FE) of Borago officinalis L., to enhance yield and quality of Lactuca sativa ‘Longifolia’, and to set up a protocol to assess their effects. To this aim, an integrated study on agronomic, physiological and biochemical aspects, including also a phenomic approach, has been adopted. Extracts were diluted to 1 or 10 mL L-1, sprayed onto lettuce plants at the middle of the growing cycle and one day before harvest. Control plants were treated with water. Non-destructive analyses were conducted to assess the effect of extracts on biomass with an innovative imaging technique, and on leaf photosynthetic efficiency (chlorophyll a fluorescence and leaf gas exchanges). At harvest, the levels of ethylene, photosynthetic pigments, nitrate and primary (sucrose and total sugars) and secondary (total phenols and flavonoids) metabolites, including the activity and levels of phenylalanine ammonia lyase (PAL) were assessed. Moreover, a preliminary study of the effects during postharvest was performed. Borage extracts enhanced the primary metabolism by increasing leaf pigments and photosynthetic activity. Plant fresh weight increased upon treatments with 10 mL L-1 doses, as correctly estimated by multi-view angles images. Chlorophyll a fluorescence data showed that FEs were able to increase the number of active reaction centers per cross section; a similar trend was observed for the performance index. Ethylene was 3-fold lower in FEs treatments. Nitrate and sugar levels did not change in response to the different treatments. Total flavonoids and phenols, as well as the total protein levels, the in vitro PAL specific activity, and the levels of PAL-like polypeptides were increased by all borage extracts, with particular regards to FEs. FEs also proved efficient in preventing degradation and inducing an increase in photosynthetic pigments during storage. In conclusion, borage extracts, with particular regard to the flower ones, appear to indeed exert biostimulant effects on lettuce; future work will be required to further investigate on their efficacy in different condition and/or species
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Claims 12
Claim · model-written summary
Borage extracts increased lettuce leaf pigments and photosynthetic activity.
Not reportedTaxonComparator
Verbatim
e0“Borage extracts enhanced the primary metabolism by increasing leaf pigments and photosynthetic activity.”
Claim · model-written summary
The 10 mL L-1 treatments increased fresh weight.
Not reportedTaxonComparator
Verbatim
e0“Plant fresh weight increased upon treatments with 10 mL L-1 doses, as correctly estimated by multi-view angles images.”
Claim · model-written summary
Multi-view angle imaging correctly estimated fresh weight response.
Not reportedTaxonComparatorValue
Verbatim
e0“Plant fresh weight increased upon treatments with 10 mL L-1 doses, as correctly estimated by multi-view angles images.”
Claim · model-written summary
Flower extracts increased active reaction centers per cross section.
Not reportedTaxonComparator
Verbatim
e0“FEs were able to increase the number of active reaction centers per cross section”
Claim · model-written summary
Flower extracts showed a similar increase in performance index.
- Outcome
- performance indexe0
Not reportedTaxonTreatmentComparatorDirection
Verbatim
e0“a similar trend was observed for the performance index.”
Claim · model-written summary
Flower extract treatment lowered ethylene threefold.
Not reportedTaxonComparator
Verbatim
e0“Ethylene was 3-fold lower in FEs treatments.”
Claim · model-written summary
Nitrate and sugar levels did not change across treatments.
Not reportedTaxonComparator
Verbatim
e0“Nitrate and sugar levels did not change in response to the different treatments.”
Claim · model-written summary
All borage extracts increased flavonoids and phenols.
Not reportedTaxonComparator
Verbatim
e0“Total flavonoids and phenols, as well as the total protein levels, the in vitro PAL specific activity, and the levels of PAL-like polypeptides were increased by all borage extracts, with particular regards to FEs.”
Claim · model-written summary
All borage extracts increased total protein levels and PAL activity.
- Treatment
- all borage extractse0
- Gene
- PALe0
- Outcome
- total protein levels, the in vitro PAL specific activitye0
- Direction
- increasede0
Not reportedTaxonComparator
Verbatim
e0“Total flavonoids and phenols, as well as the total protein levels, the in vitro PAL specific activity, and the levels of PAL-like polypeptides were increased by all borage extracts, with particular regards to FEs.”
Claim · model-written summary
All borage extracts increased PAL-like polypeptide levels.
- Treatment
- all borage extractse0
- Gene
- PAL-like polypeptidese0
- Outcome
- levels of PAL-like polypeptidese0
- Direction
- increasede0
Not reportedTaxonComparator
Verbatim
e0“Total flavonoids and phenols, as well as the total protein levels, the in vitro PAL specific activity, and the levels of PAL-like polypeptides were increased by all borage extracts, with particular regards to FEs.”
Claim · model-written summary
Flower extracts prevented pigment degradation during storage.
Not reportedTaxonComparator
Verbatim
e0“FEs also proved efficient in preventing degradation and inducing an increase in photosynthetic pigments during storage.”
Claim · model-written summary
Flower extracts increased photosynthetic pigments during storage.
Not reportedTaxonComparator
Verbatim
e0“FEs also proved efficient in preventing degradation and inducing an increase in photosynthetic pigments during storage.”