Different Responses to Salinity of <i>Pythium</i> spp. Causing Root Rot on <i>Atriplex hortensis</i> var. <i>rubra</i> Grown in Hydroponics
<i>Atriplex hortensis</i> var. <i>rubra</i> (red orache, RO) is a halotolerant species rich in nutraceutical compounds, which makes it a valuable crop for human nutrition. This plant could also be exploited for phytoremediation of contaminated soil and wastewater, and for sal...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-08-01
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| Series: | Agriculture |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2077-0472/15/15/1701 |
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| Summary: | <i>Atriplex hortensis</i> var. <i>rubra</i> (red orache, RO) is a halotolerant species rich in nutraceutical compounds, which makes it a valuable crop for human nutrition. This plant could also be exploited for phytoremediation of contaminated soil and wastewater, and for saline aquaponics. A root rot disease was observed on hydroponically grown RO plants, caused by <i>Pythium deliense</i> and <i>Pythium</i> Cluster B2a sp. Identification was based on morphology, molecular analysis (ITS and COI), and phylogenetic analysis. We assessed disease severity in plants grown in a growth chamber with nutrient solutions containing different NaCl concentrations (0, 7, and 14 g L<sup>−1</sup> NaCl). In vitro growth at different salinity levels and temperatures was also evaluated. Both <i>Pythium</i> species were pathogenic but showed different responses. <i>Pythium deliense</i> was significantly more virulent than <i>Pythium</i> Cluster B2a sp., causing a steady reduction in root dry weight (RDW) of 70% across all salinity levels. <i>Pythium</i> Cluster B2a sp. reduced RDW by 50% at 0 and 7 g L<sup>−1</sup> NaCl while no symptoms were observed at 14 g L<sup>−1</sup> NaCl. <i>Pythium deliense</i> grew best at 7 and 14 g L<sup>−1</sup> NaCl, while <i>Pythium</i> Cluster B2a sp. growth was reduced at 14 g L<sup>−1</sup> NaCl. Both pathogens had an optimum temperature of 30 °C. This is the first report of <i>Pythium</i> spp. causing root rot on RO grown hydroponically. The effective use of halophytic crops must consider pathogen occurrence and fitness in saline conditions. |
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| ISSN: | 2077-0472 |