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Sunflower has new climate risk zoning

Posted by Rafael Moro

Image: Pixabay

The Ministry of Agriculture published on Wednesday (16) Ordinance Nos. 176 to 202, which update the Agricultural Zoning of Climate Risk (ZARC) for the cultivation of sunflower in Brazil. The tool indicates the best time for planting the crop, reducing the possibility of losses due to the climate, considering soil conditions and the characteristics of the crop.

Studies for the new Zarc began last year and were validated with the production chain. “We defined the areas and sowing periods for its cultivation with probabilities of yield losses of less than 20%, 30% and 40%, due to the occurrence of adverse weather events”, explains researcher José Renato Bouças Farias, from Embrapa Soja .

New risk factors were considered, associating water, thermal and phytosanitary issues. According to the researcher, sunflower is little influenced by variations in latitude and altitude, has a tolerance to low temperatures and is relatively resistant to drought. Regarding the water needs for growing sunflowers, Farias states that the ideal would be around 500 to 700 mm of available water, well distributed throughout the cycle. “The most sensitive phases to water deficit occur during sowing and plant emergence and, mainly, from the beginning of the formation of the capitulum to the beginning of flowering, followed by the formation and filling of grains”, emphasizes Farias.

Another factor considered as one of the parameters in Zarc was the association of climatic conditions with phytosanitary risk, since the climate may or may not favor the development of important diseases that are difficult to control. White rot, caused by the fungus Sclerotinia sclerotiorum, for example, is associated with cold, damp conditions. On the other hand, alternaria spot, caused by the fungus Alternaria helianthi, is due to high temperatures and excessive rainfall. “Our study also sought to delimit the areas and identify the periods of lower climatic risk for the occurrence of phytosanitary problems and, thus, favor the exploitation of the sunflower crop in Brazil”, he highlights.

Zarc is based on historical series of approximately 30 years, obtained from networks of ground, meteorological and rainfall stations, conventional and automatic, in addition to state networks maintained by institutions or public companies. There are about 3,500 data points distributed throughout the national territory, from the base generated by interpolation from 735 meteorological stations.

Sunflower can be cultivated from Rio Grande do Sul to Roraima. The National Supply Company (Conab) estimates that the cultivated area in Brazil in 2021 will be 31.5 thousand ha, with 70% in the state of Goiás (about 20 thousand ha), followed by Mato Grosso (8,500 ha). ha), Rio Grande do Sul (1.5 thousand ha), Minas Gerais (800 ha) and Distrito Federal (700 ha).

Despite the different uses of sunflower and the crop's potential as a component of diversified and profitable production systems, Farias explains that the variability in water availability is the main limitation to the expression of sunflower yield potential in Brazil.

By: Eliza Maliszewski | Agrolink

This text was automatically translated from Portuguese.