The ameliorating effects of polyamine supplement on physiological and biochemical parameters of Stevia rebaudiana Bertoni under cold stress

Figures & data

Figure 1. Changes in photosynthetic pigments (A), leaf SPAD chlorophyll (B) and chlorophyll fluorescence (C) under cold (48 and 96 h) and cold-polyamine treatments.

Different letters represent a significant difference of means ±SE at p ≤ .05.

Figure 2. Changes in H₂O₂ (A), malondialdehyde (B), content and catalase (C); polyphenol oxidase (D) and ascorbate peroxidase (E) under cold (48 and 96 h) and cold-polyamine treatments.

Different letters represent a significant difference of means ±SE at p ≤ .05.

Figure 3. Changes in steviol glycosides (A), proline (B), and glycine betaine (C) content under cold (48 and 96 h) and cold-polyamine treatments.

Different letters represent a significant difference of means ±SE at p ≤ .05.

Figure 4. Changes in Bradford total protein (A), free amino acids (B), and protease activity (C) under cold (48 and 96 h) and cold-polyamine treatments.

Different letters represent a significant difference of means ±SE at p ≤ .05.

Table 1. Changes in the fatty acid composition of stevia leaves under cold and polyamine supplement treatment after 96 h of exposure under 4 °C growth condition.

Fatty acid	Molecular formula	Content in leaves (μg mg^−1)
		Control	Cold	Cold + Polyamine	Polyamine
Caproic acid	C6H12O2	.077	ND	ND	ND
Caprylic acid	C8H16O2	.165	ND	ND	.11
Pelargonic acid	C9H18O2	.088	ND	ND	.20
Myristic acid	C14H28O2	.237	.550	.130	.506
Palmitic acid	C16H32O2	5.093	6.226	.660	1.397
Stearic acid	C18H36O2	2.761	7.260	1.232	.11

Note:

ND: not determined.