Boro, cultivar e local de cultivo afetam a produtividade de aquênios e óleo de girassol?

• Autor(a) principal: Silva, Fred Denilson Barbosa da
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1192
• topic: Helianthus Annuus; Nutrição de plantas; Qualidade do óleo; Helianthus Annuus; Plant nutrition; Quality of oil; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

In sunflower cultivation, fertilization with boron (B) has been critical in the productivity of grain and oil. The choice of cultivar and sowing season is essential for attaining high yields of achenes with oil of better quality. This study aimed to evaluate the nutritional status, productivity of achenes and oil content of three sunflower cultivars as variable doses of B and two gowing sites (Januária-MG and Coimbra-MG). Four experiments were conducted. In the first experiment, were applied the doses of 0, 3, 6, 9 and 12 kg ha-1 of B. The cultivar used was the M-734. The experimental design was a randomized block with four replications. Other experiments were conducted in Coimbra-MG and Januária-MG. In Coimbra, the first experiment was carried out from March to August (Coimbra, March 2010)and the other from May to September (Coimbra, May 2010). In Januária, the experiment was carried out from March to July (Januária, March 2010). The cultivars used were BR-122/V2000, M-734 and MG-02. In this experiment, the doses were 0 and 6 kg ha-1 of B. The experimental design was a randomized block with four replications. The factorial was 3 cultivars x 2 doses of boron within three growing conditions. Nitrogen, P, K, Ca, Mg, S and B, Fe, Mn, Zn and Cu content were evaluated in the leaf, achene and oil, the fatty acid composition of the lipid fraction and protein content. The productivity and mass of a thousand achene and oil yield were determined. The regression analysis was used in the experiment which has determined the critical content of B in the soil and leaf. When appropriate, the Tukey test was applied in the work that assessed the effect of cultivars and B doses in three environments. The highest doses of technical and economic efficiency were 6.29 and 3.13 kg ha-1 of B, respectively. The critical level of B at 0-20 cm and 20-40 cm of soil for optimum economic efficiency through the application of B was 0.44 and 0.43 mg dm-3 of B, respectively. The critical level of B in the index leaf with the highest economic efficiency dose was 32.4 mg kg-1 of B. The doses of B did not affect the oil content, neither the fatty acid composition of palmitic, stearic, oleic and linoleic. Boron fertilization increased K content in the index leaf in Coimbra cultivation with sowing in March and May, regardless of cultivar. Cultivar BR-122/V2000 showed higher P content in the leaf when cultivated in the presence of B fertilization. Mean levels of nutrients in the leaf in three experiments followed the descending sequence for macronutrient K> N> Ca> Mg> P> S and micronutrient Mn> Zn> B = Fe> Cu. The cultivars M-734 and MG-02 showed higher productivity of achenes in Januária. In Coimbra cultivations, cultivars showed similar productivities. In this location, sowing in May reduced the productivity of achenes' cultivars. The cultivar BR122-V2000 increased protein content without compromising the oil content when the air temperature was higher in the maturity phase. This cultivar relied on higher air temperature to synthesize more oleic fatty acid. The cultivar M-734 synthesized higher content of palmitic when the air temperature was lower. The synthesis of oleic and linoleic fatty acid in cultivar MG-02 did not vary with growing conditions. The synthesis of stearic fatty acid of the cultivars did not vary with changes in air temperature. The cultivation in Januária with sowing in March increased the content of oleic fatty acid. The highest percentage of linoleic acid was observed in Coimbra, sowed in March.