Fig 1.
Biosynthetic pathway of steviol and its glycosides leading to rebaudioside A.
GGPP, geranylgeranyl diphosphate; CPS, copalyl diphosphate synthase; KS, kaurene synthase; KO, kaurene oxidase; KAH, kaurenoic acid hydroxylase; UGTs, UDP-glycosyltransferases.
Table 1.
Composition of fertilizing solution and quantities supplied for experiments under controlled conditions (CC and SCC).
Table 2.
Characteristic of the four location sites for experiments under field conditions.
Fig 2.
Specific leaf nitrogen (SLN, g m-2; mean±SE) and nitrogen content in leaves (N content, %; mean±SE) for genotypes A and B in controlled (CC), semi-controlled (SCC) and field conditions (FC) at different levels of fertilization (N1, N2, N3) or in different location sites (I, II, III, IV).
Fig 3.
(A) Relationship between nitrogen content in leaves (N content, %) and plant biomass (g DM) and (B) Relationship between N content (%) and steviol glycoside content in leaves (SVgly content, %) for genotypes A and B in controlled (CC), semi-controlled (SCC) and field conditions (FC).
Table 3.
Yield components (mean ± SEM with SEM calculated from the ANOVA residual mean square with 28 df under CC, 32 df under SCC and 16 df under FC) as affected by genotype (G) = A and B and nitrogen supply (N) = N1, N2, and N3 or location site (LS) = I, II, III, IV.
Table 4.
Parameters values for light-response curves (mean ± SEM with SEM calculated from the ANOVA residual mean square with 33 df under CC and 32 df under SCC) as affected by genotype (G) = A and B and nitrogen supply (N) = N1, N2, and N3.
Fig 4.
Relationship between specific leaf nitrogen (SLN, g.m-2) and light-saturated photosynthetic rates (Amax, μmol.m-².s-1) for genotypes A and B in controlled (CC) and semi-controlled conditions (SCC).
Fig 5.
Relationship between nitrogen content in leaves (N content, %) and RA-to-ST ratio and relationship between steviol glycoside content in leaves (SVgly content, %) and RA-to-ST ratio for genotype A in controlled (CC), semi-controlled (SCC) and field conditions (FC).
Table 5.
SVgly proportions (mean ± SEM with SEM calculated from the ANOVA residual mean square with 28 df under CC, 32 df under SCC and 16 df under FC) as affected by genotype (G) = A and B and nitrogen supply (N) = N1, N2, and N3 or location site (LS) = I, II, III, IV.