Abstract
The objective of this work was to evaluate the response of sunflower cultivars submitted to increasing levels of phosphate fertilization in two crops. The experimental design was a randomized complete block design with four replicates in subdivided plots, where five doses of simple superphosphate (0, 50, 100, 150, and 200 kg ha-1 P2O5) were allocated to the plots and three sunflower cultivars (Aguará 06, Altis 99, and Embrapa 122-V2000) were assigned to the subplots. The variables evaluated were the P content in the diagnostic leaf, number of achenes per capitulum, achene yield (kg ha-1), oil content (%) and oil yield. The phosphorus doses increased the components of production. The dose that provided the best sunflower performance varied for the different cultivars. Among the doses studied, fertilization with 100 kg ha-1 P2O5 in the 2016 agricultural crop and 150 kg ha-1 P2O5 in the 2017 agricultural crop provided the best conditions for sunflower cultivation. The cultivar Aguará 06 produced more achenes and oil than the other cultivars analyzed in the agricultural crops.
Highlights
Sunflower (Helianthus annuus L.) is an oleaginous species of great importance in the world; has important agronomic characteristics, broad phenotypic plasticity, several purposes, and a high content and quality of oil in its achenes; and is considered one of the four main oleaginous crops with the highest index of expansion in the world (Araújo, Chaves, Guerra, Véras, & Oliveira, 2014).In the state of Rio Grande do Norte, sunflower production has been widespread in recent years, mainly in the western region of the state, where sunflower is cultivated in rainfed and irrigated systems in crop rotation, to meet the demand of the National Production Program and Biodiesel Use - PNPB (Cavalcante Júnior et al, 2013)
According to the results of the joint analysis of the variables evaluated as a function of the agricultural crops, of the doses of P and of the cultivars of sunflower, triple interactions were observed for all characteristics evaluated
The highest accumulation of P was obtained at 200 kg ha-1 P2O5, with maximum values of 5 g kg-1 (Embrapa BRS 122-V2000) and 4 g kg-1 (Altis 99), except for Aguará 06, which obtained a maximum concentration of 4 g kg-1 at the dose of 182 kg ha-1 P2O5 in the 2016 agricultural crop (Figure 2A)
Summary
Sunflower (Helianthus annuus L.) is an oleaginous species of great importance in the world; has important agronomic characteristics, broad phenotypic plasticity, several purposes, and a high content and quality of oil in its achenes; and is considered one of the four main oleaginous crops with the highest index of expansion in the world (Araújo, Chaves, Guerra, Véras, & Oliveira, 2014).In the state of Rio Grande do Norte, sunflower production has been widespread in recent years, mainly in the western region of the state, where sunflower is cultivated in rainfed and irrigated systems in crop rotation, to meet the demand of the National Production Program and Biodiesel Use - PNPB (Cavalcante Júnior et al, 2013). Sunflower (Helianthus annuus L.) is an oleaginous species of great importance in the world; has important agronomic characteristics, broad phenotypic plasticity, several purposes, and a high content and quality of oil in its achenes; and is considered one of the four main oleaginous crops with the highest index of expansion in the world (Araújo, Chaves, Guerra, Véras, & Oliveira, 2014). The selection of cultivars is one of the main concerns in a production system, mainly due to the genotype and environment interaction, which necessitates tests in different agricultural years to determine the agronomic behavior of the genotypes and their adaptation to the different local conditions (Tarsitano, Laforga, Proença, & Rapassi, 2016). P deficiency in the plants, mainly at the beginning of the vegetative cycle, results in slower growth, a delay in flowering, a smaller number of achene that reach the filling stage, and a lower oil content (Prado & Leal, 2006)
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