Abstract
Background: Steviol glycosides (SGs) from Stevia rebaudiana (Bertoni) Bertoni have garnered global interest due to their intense sweetness (over 300 times sweeter than sucrose) with negligible calories and potential health benefits. This study aims to address the low productivity of Greek stevia crops in terms of dry leaf yield (1235 kg/ha) despite favorable Greek agro-climatic conditions. Aim: To investigate the agronomic reasons behind the low productivity of stevia cultivation in Greece, with final target to enhance the yield of dry leaves and major steviol glycosides (SGs) by exploring new cultivar and nutrition management strategies. Approach: A pot experiment assessed the impact of three foliar plant biostimulants (calcite, seaweed extract, and amino acids) and two soil fertilizers (organic and conventional) on aerial biomass productivity and major steviol glycosides (stevioside and rebaudioside A) of two new stevia cultivars (cvs Olga and Ambrosia). Key growth and productivity traits such as height, covered area, leaf chlorophyll concentration, yield in dry leaves, leaf SGs concentration, and rebaudioside A/stevioside ratio were measured. Main results: Under optimal Greek agro-climatic conditions (day length > 13 h, average temperature 23.4°C, soil moisture 41 - 43%, harvest time ≥ 110 DAT), an organic substrate enriched with N rate 1.2 g per plant from high-quality organic fertilizer (C/N < 20), along with a combination of foliar plant biostimulants (calcite 0.3%, seaweed extract 0.02%, amino acids 0.2% at low dose rates) facilitated significant improvements in dry leaf yield (87 g per plant) and major steviol glycosides concentration (17.6 g per plant), with major SGs concentration reaching 20.28% (11.09% stevioside + 9.22% rebaudioside A), and the highest rebaudioside A/stevioside ratio (0.83) in the tested stevia cultivar (cv. Olga). Conclusion: The study suggests that the current substrate (N rate 0.88 g/plant) and cultivar (cv. SRB-128) contribute to the low productivity of stevia cultivation in Greece. It highlights the potential of suitable cultivars treated with appropriate substrate and foliar plant biostimulants to bridge the productivity gap between conventional and organic farming in the Mediterranean region. However, further research on biostimulant mechanisms, cultivar selection, and nutrition management is necessary to optimize leaf biomass, steviol glycosides concentration, and rebaudioside A/stevioside ratio across diverse local environments.
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Claims 6
Claim · model-written summary
The combined organic substrate and foliar biostimulants significantly improved dry leaf yield to 87 g per plant in Olga.
- Taxon
- Stevia rebaudiana
Stevia rebaudianat0 - Treatment
- an organic substrate enriched with N rate 1.2 g per plant from high-quality organic fertilizer (C/N < 20), along with a combination of foliar plant biostimulants (calcite 0.3%, seaweed extract 0.02%, amino acids 0.2% at low dose rates)e0
- Outcome
- dry leaf yielde0
- Direction
- improvementse0
- Value
- 87 g per plante0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an organic substrate enriched with N rate 1.2 g per plant from high-quality organic fertilizer (C/N < 20), along with a combination of foliar plant biostimulants (calcite 0.3%, seaweed extract 0.02%, amino acids 0.2% at low dose rates) facilitated significant improvements in dry leaf yield (87 g per plant)”
t0“Stevia rebaudiana”
Claim · model-written summary
The same treatment improved major steviol glycosides to 17.6 g per plant.
- Taxon
- Stevia rebaudianaStevia rebaudianat0
- Treatment
- an organic substratee0
- Outcome
- major steviol glycosides concentratione0
- Direction
- improvementse0
- Value
- 17.6 g per plante0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an organic substrate enriched with N rate 1.2 g per plant from high-quality organic fertilizer (C/N < 20), along with a combination of foliar plant biostimulants (calcite 0.3%, seaweed extract 0.02%, amino acids 0.2% at low dose rates) facilitated significant improvements in dry leaf yield (87 g per plant) and major steviol glycosides concentration (17.6 g per plant)”
t0“Stevia rebaudiana”
Claim · model-written summary
Major glycoside concentration reached 20.28% in Olga.
- Taxon
- Stevia rebaudianaStevia rebaudianat0
- Outcome
- major SGs concentratione0
- Direction
- reachinge0
- Value
- 20.28%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“major SGs concentration reaching 20.28% (11.09% stevioside + 9.22% rebaudioside A)”
t0“Stevia rebaudiana”
Claim · model-written summary
Stevioside concentration was 11.09%.
- Taxon
- Stevia rebaudianaStevia rebaudianat0
- Outcome
- steviosidee0
- Value
- 11.09%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“11.09% stevioside + 9.22% rebaudioside A”
t0“Stevia rebaudiana”
Claim · model-written summary
Rebaudioside A concentration was 9.22%.
- Taxon
- Stevia rebaudianaStevia rebaudianat0
- Outcome
- rebaudioside Ae0
- Value
- 9.22%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“11.09% stevioside + 9.22% rebaudioside A”
t0“Stevia rebaudiana”
Claim · model-written summary
Olga had the highest rebaudioside A to stevioside ratio, at 0.83.
SteviaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the highest rebaudioside A/stevioside ratio (0.83) in the tested stevia cultivar (cv. Olga)”
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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.