ABSTRACT
The Northeast region of Brazil is characterized by a tropical climate and high air temperatures, which can negatively affect the growth and physiological processes of strawberry plants (Fragaria x ananassa Duch) in the short- or long-term. In this context, the use of adapted varieties and technologies such as soil conditioners is necessary. Thus, the objective of this study was to assess the physiological responses and the thermal index of strawberry cultivars grown under hydrogel doses in the substrate. The study was conducted in a protected environment in Guaraciaba do Norte, Ceará state, Brazil, using a randomized block experimental design with four replicates, in a 5 × 2 factorial arrangement consisting of five hydrogel doses in the substrate (0, 1, 2, 3, and 4 g L-1) and two strawberry cultivars (‘Albion’ and ‘San Andreas’). Growth variables (number of leaves, crown diameter, and plant height) were evaluated at 15 and 45 days after transplanting (DAT). Gas exchanges (stomatal conductance, transpiration rate, CO2 assimilation rate, and intercellular CO2 concentration), physiological indices (intrinsic water use efficiency, instantaneous carboxylation efficiency, and instantaneous water use efficiency), and thermal index were evaluated at 90 DAT. Strawberry plant growth increased significantly as the hydrogel dose in the substrate was increased. The hydrogel dose of 4 g L-1 reduced gas exchanges at 90 DAT, regardless of the cultivar. Plants of the cultivar San Andreas showed higher intrinsic water use efficiency and lower thermal index when grown under the hydrogel dose of 4 g L-1.
Key words:
Fragaria x ananassa Duch; polymer; infrared thermography
HIGHLIGHTS:
Increasing hydrogel doses in the growing medium boosts strawberry plant growth.
Hydrogel reduces gas exchange in strawberry crops 90 days after transplanting.
Increasing hydrogel doses in the substrate provides conditions for reducing the thermal index of strawberry plants.
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Vertical lines represent the standard error of the mean (n = 4); ** - Significant at p ≤ 0.01 by the F-test. Means followed by the same letter are not significantly different from each other by the Tukey’s test (p ≤ 0.05); () cultivar Albion; () cultivar San Andreas, DAT - Days after transplanting; CV - Coefficient of variation
Vertical lines represent the standard error of the mean (n = 4); ** - Significant at p ≤ 0.01 by the F-test. Means followed by the same letter are not significantly different from each other by the Tukey’s test (p ≤ 0.05); () cultivar Albion; () cultivar San Andreas; CV - Coefficient of variation
Vertical lines represent the standard error of the mean (n = 4); ** and * - Significant at p ≤ 0.01 and p ≤ 0.05, respectively, by the F-test. Mean followed by the same letter do not differ statistically by Tukey’s test (p ≤ 0.05); () cultivar Albion; () cultivar San Andreas; CV - Coefficient of variation