Sunflower has been mentioned in the literature as a plant that requires large amounts of boron (B) to achieve a successful crop. This study aimed at evaluating the influence of sunflower fertilization with boron on the soil nutrient concentration, index leaf, seed yield, fatty acids’ composition of sunflower oil, and oil content. Cultivar M734 was selected for boron fertilization at 0, 3, 6, 9, and 12 kg ha−1 rates. The maximum economic return was obtained with 3.13 kg ha−1. Neither oil content nor fatty acid composition was affected by boron. With proper irrigation, the M734 cultivar was able to absorb boron in the 0 − 40-cm layer, ultimately producing about 3000 kg ha−1 of seeds in soils with only 0.30 mg kg−1 of boron. Based on these results, it is suggested that the boron fertilization program be expanded to include the soil strata at 0−20 cm and 20−40 cm.

Influence of Boron on Sunflower Yield and Nutritional Status

The objective of this study was to evaluate the effect of Ca and Mg silicate and B on the gas exchange, leaf water potential and chlorophyll fluorescence parameters in the sunflower variety Embrapa 122 -V2000 under water stress conditions. The trial was conducted in Red Yellow Latosol with very clayey texture, with contrasting levels of Si and B and subjected to water deficit. The experimental design was randomized blocks in a 24 factorial arrangement, with five replicates. Treatments consisted of the combination of two acidity corrective agents (calcium magnesium silicate and dolomitic limestone), two levels of base saturation (30 and 70%), two levels of B (0.18 mg dm-3 - value available in the soil and 1.20 mg dm-3) and two water regimes (with and without water stress from the beginning of flowering). It can be concluded that the supply of Si and B can reduce the damage to sunflower caused by water stress.

/pdf/silicon-and-boron-mitigate-the-effects-of-water-deficit-on-11kp0d3nqm.pdf

Silicon and boron mitigate the effects of water deficit on sunflower

The objectives of this study were: to evaluate the leaching potential of B in a Latossolo Vermelho-Amarelo (Oxisol) as a function of sources and doses of this micronutrient; among the sources tested (boric acid, ulexite and the commercial source H2 Boro), to determine the one with the lowest leaching potential; to evaluate leaching losses at different doses in each soil layer evaluated; and to identify chemical and physical variables of soils that influence B leaching. For that, two experiments were conducted in a greenhouse. The first one tested B leaching in the soil, with the three sources under study and five doses of B (0; 12; 24; 36; and 48 kg ha -1 ), whereas the second experiment evaluated the influence of soil physical and chemical attributes on B leaching using soils randomly collected in 22 localities in southeastern Goias, Brazil. Regardless of the dose applied, ulexite led to the lowest soluble B content in the profile of the analyzed soils and also in the leachate. Boric acid was the only source that showed a different behavior in relation to B content in the different soil layers and in the leachate. In the soil layer from 21 to 30 cm, ulexite is the source with the lowest soluble B content. The behaviors of the more soluble sources, in this case boric acid and H2 Boro (H2 Agrosciences - Monoethanolamine borate), regardless of the dose, are very similar, being highly leachable in the profile of the Oxisol used. Soils with clayey texture and higher values of H+Al and CEC were able to retain higher B contents in the upper portion their profiles (layers from 0 to 10 cm and 11 to 20 cm), but soils with sandy texture and higher values of sum of bases showed greater B losses by leaching.

/pdf/boron-dynamics-in-agricultural-soils-of-the-cerrado-study-on-2t0iuqwp8p.pdf

Boron Dynamics in Agricultural Soils of the Cerrado: Study on Sources, Doses and Leaching

SILVA, Fred Denilson Barbosa da, D.Sc., Universidade Federal de Viçosa, September, 2012. Boron, cultivar and growing conditions does affects the productivity of achenes and sunflower oil? Adviser: Paulo Geraldo Berger. Co-advisers: Luiz Antônio dos Santos Dias, Leonardo Angelo de Aquino and Denise Cunha Fernandes dos Santos Dias. 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 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 BR122/V2000, M-734 and MG-02. In this experiment, the doses were 0 and 6 kg ha 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 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 of B, respectively. The critical level of B in the index leaf with the highest economic efficiency dose was 32.4 mg kg 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.

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

O girassol apresenta caracteristicas favoraveis ao sistema de semeadura direta, se enquadrando em uma rotacao de culturas. Contudo, e sensivel a deficiencia de boro, caracteristica predominante em grande parte dos solos tropicais. Objetivou-se avaliar o efeito de doses de fertilizantes boratados aplicados no sulco de semeadura e pulverizacao foliar, sobre o crescimento das plantas, rendimento e tamanho de graos de girassol. Conduziu-se o experimento em casa de vegetacao, sendo que os tratamentos constituiram-se de quatro doses de borax (0; 1; 2 e 3 kg ha-1 de B) aplicadas no solo e quatro doses de acido borico (0; 0,5; 1 e 2 kg ha-1 de B na calda de pulverizacao) aplicadas via foliar. Duas plantas por vaso foram conduzidas ate o estagio de maturacao fisiologica dos graos, ocasiao em que foram coletados os caules, folhas e capitulos, que tiveram as materias secas determinadas, alem da contagem e \npesagem de graos miudos e graudos. O B aplicado no sulco de semeadura incrementou a producao de fitomassa total e a producao de graos de girassol. No entanto, quando em interacao com doses elevadas de B foliar, essas variaveis foram prejudicadas. O tamanho dos graos de girassol foi aumentado com a adubacao boratada foliar, quando nao se aplicou B no solo ou com somente 1 kg ha-1 de B no sulco de semeadura. Em contrapartida, quando se adicionou doses de 2 e 3 kg ha-1 de B na instalacao da cultura, altas doses de B pulverizadas nas folhas comprometeram a formacao de graos.___ABSTRACT: Sunflower crop is a good option to no-tillage system; however, it is sensible to low B availability, what is common in tropical soils. The objective of this study was to evaluate the crop development, grain yield and grain size as affected by B fertilizer doses applied in the sowing and by leaf application. The experiment was conducted in controlled conditions, with four Borax doses (0; 1; 2 e 3 kg B ha-1) in the sowing interacting with four Boric Acid doses (0; 0,5; 1 e 2 kg B ha-1) by leaf application. The plants were managed until grain physiological maturity, when stems, leaves and capitula were sampled, besides the counting and weighing of two grain classes separated by size. The B fertilizer applied in the sowing lines increased total dry matter phytomass and grain yield. However, when interacting with high doses of B by leaf application, these values decreased. Grain size was increased with leaf fertilization, when B was not applied in the soil or with only 1 kg B ha-1 in the sowing line. On the other hand, when B was applied from 2 to 3 kg ha-1 in the crop sowing, high doses of leaf fertilizer affected grain filling.

H. Grassi Filho

Papers

Grain development and phytomass production of sunflower as affected by boron fertilization.