Impact of aluminum supply on the growth of seed-grown yerba mate (Ilex paraguariensis) seedlings
ABSTRACT
Aluminum (Al) has long been regarded as toxic to plants, but recent research suggests it may also play a beneficial role in plant nutrition. Yerba mate (Ilex paraguariensis) is known for naturally thriving in acidic and Al-rich soils. The objective of the present study was to evaluate the effect of supplying Al, with or without the addition of controlled-release mineral fertilization, on the growth of yerba mate seedlings obtained from seeds. The mineral fertilization of the substrate enhanced the growth, biomass production, and quality of the produced yerba mate seedlings. Al supply did not exhibit beneficial effects on the development of seed-propagated yerba mate seedlings, except for root fresh volume, which showed a positive response to moderate Al doses. The yerba mate seedlings had a high tolerance to the presence of Al in the substrate, withstanding monthly applications of up to 1,000 mg Al3+ per dm-3 of substrate without displaying toxicity symptoms. Nevertheless, higher Al doses caused severe toxicity in yerba mate seedlings, which was visibly manifested by the development of short, thick, and dark-colored roots. In the shoot of the seedlings, Al toxicity symptoms generally occurred indirectly, as evidenced by reduced growth and a decrease in dry matter production. However, in the most affected plants, dark spots were observed on the shoot, starting at the tips of the younger leaves and progressing across the entire leaf, ultimately causing leaf abscission and, subsequently, plant death.
Key words:
acidic soil; beneficial element; toxic element; toxicity; plant nutrition
HIGHLIGHTS:
Yerba mate is the most widely cultivated non-timber forest species in Paraná state, Brazil.
Fertilization improved growth and quality of yerba mate seedlings.
Yerba mate seedlings showed tolerance to aluminum but developed toxicity at high doses.
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Source: Eduardo Luiz Costa Tobias Pinto
ns indicates no statistically significant difference according to the F-test (p > 0.05); *, **, and *** indicate statistically significant differences at p ≤ 0.05, p ≤ 0.01, and p ≤ 0.001, respectively. A, C, and E represent the effect of fertilization. B, D, and F show the response to Al doses. Means followed by different uppercase letters differ significantly (Tukey’s test, p ≤ 0.05). The curves in panels D and F represent the fitted regression models describing the relationship between Al doses and plant height
* and *** indicate statistically significant differences at p ≤ 0.05 and p ≤ 0.001, respectively. The curves represent the fitted regression models describing the relationship between Al doses and plant height: the blue line corresponds to unfertilized plants, and the red line corresponds to fertilized plants. Within each Al dose, means followed by different lowercase letters differ significantly between fertilization treatments (Tukey’s test, p ≤ 0.05)
n.s. indicates no statistically significant difference according to the F-test (p > 0.05); *, **, and *** indicate statistically significant differences at p ≤ 0.05, p ≤ 0.01, and p ≤ 0.001, respectively. A, C, and E represent the effect of fertilization. B, D, and F show the response to Al doses. When a significant effect of fertilization treatments was observed, means followed by different uppercase letters differ significantly (Tukey’s test, p ≤ 0.05). The curves in panels D and F represent the fitted regression models describing the relationship between Al doses and collar diameter
*, **, and *** indicate statistically significant differences at p ≤ 0.05, p ≤ 0.01, and p ≤ 0.001, respectively. The curves represent the fitted regression models describing the relationship between Al doses and collar diameter: the blue line corresponds to unfertilized plants, and the red line corresponds to fertilized plants. Within each Al dose, means followed by different lowercase letters differ significantly between fertilization treatments (Tukey’s test, p ≤ 0.05)
*, **, and *** indicate statistically significant differences at p ≤ 0.05, p ≤ 0.01, and p ≤ 0.001, respectively. The curves represent the fitted regression models describing the relationship between Al doses and dry matter production: the blue line corresponds to unfertilized plants, and the red line corresponds to fertilized plants. Within each Al dose, means followed by different lowercase letters differ significantly between fertilization treatments (Tukey’s test, p ≤ 0.05)
Source: Eduardo Luiz Costa Tobias Pinto
Source: Eduardo Luiz Costa Tobias Pinto
Source: Eduardo Luiz Costa Tobias Pinto
Source: Eduardo Luiz Costa Tobias Pinto
*, **, and *** indicate statistically significant differences at p ≤ 0.05, p ≤ 0.01, and p ≤ 0.001, respectively. The curves represent the fitted regression models describing the relationship between Al doses and root fresh volume or Dickson quality index: the blue line corresponds to unfertilized plants, and the red line corresponds to fertilized plants. Within each Al dose, means followed by different lowercase letters differ significantly between fertilization treatments (Tukey’s test, p ≤ 0.05)