Use of algae extract as an agent to mitigate salt stress in sunflower crop¹

Uso de extrato de algas como um agente mitigador do estresse salino na cultura de girassol

ABSTRACT

For the use of saline waters in agriculture to be a viable option, solutions must be adopted to mitigate the impacts caused by these waters. In this context, the present study aimed to evaluate the foliar application of algae (Ascophyllum nodosum) extract as a strategy to mitigate the deleterious effects of salinity on the production and post-harvest variables of the ‘BRS 324’ sunflower. The experiment was conducted in a randomized block design with a split-split-plot arrangement, composed of four salinity levels of water (1.2, 3.0, 4.5, and 6.0 dS m^-1) and four doses of algae extract (0, 100, 150, and 200% of recommended dose) in two crop cycles, with four blocks. The 100% of the recommended dose (32 mg L^-1) of the algae extract positively influenced the 1000-achenes weight (increases of 6.05 and 3.63% for the levels of 1.2 and 3.0 dS m^-1, respectively) and the achene yield (increments of 7.07 and 4.59% for the levels of 1.2 and 3.0 dS m^-1). The algae extract did not influence the oil and protein content and yield. The increase in salinity levels reduced all variables studied. Algae extract mitigated the deleterious effects of salinity on 1,000-achene weight and yield of achenes at the lowest water salinity level (1.2 dS m^-1). The most effective dose of the algae extract to mitigate the negative effects of salinity on the 1,000-achene weight and achene yield was 100% (32 mg L^-1) of the recommendation of the extract.

Key words:
salinity; Ascophyllum nodosum; Helianthus annuus

HIGHLIGHTS:

The electrical conductivity of irrigation water above 1.2 dS m^-1 reduces sunflower production.

The algae extract attenuates the deleterious effect of salts on sunflowers up to an electrical conductivity of the water of 1.2 dS m^-1.

Sunflower production variables were favored by algae extract.