Doroteu Honório Guedes Filho

Cultivo de girassol em sistema hidropônico sob diferentes níveis de salinidade

Hydroponic systems have constituted an alternative for combating the adverse natural factors of agricultural production in the semi-arid regions of Brazil, such as shallow rocky and infertile soils, and the scarcity of good quality water resources (high salt content). This work studied the yield of the sunflower (variety EMBRAPA 122/V-2000) destined for achene and fodder (phytomass) production, grown hydroponically, using coconut fiber as substrate and irrigated with brackish water of varying salinities. The experimental layout used was completely randomized into a 5 x 2 factorial design with three replications, five levels of water salinity and two planting density - with one or two plants per pot being studied. The irrigation water was composed of 50% standard nutrient solution and 50% municipal water supply, with added levels of NaCl, resulting in an eletrical conductivity (ECw) of 1.7; 4.3; 6.0; 9.0 and 11.5 dS m-1. The differential density of the sunflower plants positively affected the yield components of grain and biomass, showing greater viability when using two plants per pot.

Crescimento de cultivares de girassol ornamental influenciado por doses de silício no solo

Few experimental studies have been carried out to analyze growth of the ornamental sunflower under protected environment conditions. Thus, the aim of this study was to evaluate effects of different silicon doses on the growth of two cultivars of ornamental sunflower. The experiment was conducted in a greenhouse, from September to December 2010. The treatments were arranged in a completely randomized design with three replications in a 5 x 2 factorial scheme, referring to doses 0; 2; 4; 6 and 8 g of Si per pot and cultivars of ornamental sunflower Jardim Amarelo Alto and Sol Vermelho. Each experimental unit consisted of a plastic pot with a capacity of 10 L, with 5.33 L of soil. All experimental units were fertilized with N:P2O5:K2O in a dose of 60-80-80 kg ha-1. Doses of silicon significantly increased the external capitulum diameter and the total opening of flower bud (days) sunflower plant. The cultivar Sol Vermelho showed better response to the application of silicon compared to Jardim Amarelo Alto.

Substratos e diferentes concentrações da solução nutritiva preparada em água residuária no crescimento do girassol

A utilizacao da agua residuaria no preparo da solucao nutritiva em cultivos semi-hidroponicos, tanto incrementa a oferta de agua em regioes de escassez quanto recicla os nutrientes nela contidos disponibilizando-os as plantas. Considerando estes aspectos, buscou-se com o presente trabalho, analisar o crescimento e desenvolvimento de plantas de girassol para fins ornamentais, cultivadas em sistema semi-hidroponico, utilizando agua residuaria no preparo de solucoes nutritivas com concentracoes nutricionais crescentes (55; 70; 85 e 100%) a base de NPK, e diferentes substratos de cultivo (fibra de coco, areia lavada e bagaco de cana de acucar). Os tratamentos foram distribuidos em um delineamento inteiramente casualizado, analisado em esquema fatorial 4x3, com tres repeticoes, totalizando 36 unidades experimentais. Concluiu-se que mesmo com a reducao da concentracao de NPK da solucao nutritiva para 55%, o crescimento de plantas de girassol para fins ornamentais permanece dentro do padrao comercial, desde que seja utilizado agua residuaria no preparo da solucao nutritiva e fibra de coco ou areia lavada como substrato de cultivo.

Eficiência do uso da água para girassol cultivado em sistema hidropônico sob estresse salino

In order to identify alternatives for the use of saline water in agricultural production, the effects of the use of brackish water in the preparation of the nutrient solution for the cultivation of sunflower (cv. EMBRAPA 122-V2000) were studied in hydroponic system on consumption and efficiency of water use for the production of achenes and biomass. A completely randomized design was used, analyzed in a 5x2 factorial scheme with three replications. The factors studied were five levels of salinity of nutrient solution (1.7 - control; 4.3; 6.0; 9.0; and 11.5dS m-1) and two plant densities - one or two plants per vessel. It was concluded that the water consumption of sunflower is a variable sensitive to the salinity of the nutrient solution, especially after the fourth week of crop, and that the efficiency of water use in the production of achenes and biomass of sunflower is greater when the plant density increases from one to two plants per vessel, even under saline stress.

IRRIGAÇÃO COM ÁGUA SALINA E ADUBAÇÃO NITROGENADA NOS COMPONENTES DE PRODUÇÃO E RENDIMENTO DO GIRASSOL

Due to the quantitative and qualitative limitation of water resources, saline water irrigation and nitrogen (N) fertilisation can contribute positively to the expansion of sunflower cultivation in the semiarid region of Northeast Brazil. Thus, this study aimed to evaluate production components and yield of sunflower, cv. „Embrapa 122-V2000‟, irrigated with waters of different salinity levels (electrical conductivity – ECw) and fertilised with varying amounts of N in a field experiment in an eutrophic Quartzarenic Neosol from November 2012 to February 2013. The experiment was performed in a completely randomised block design in split plots, in a 5 x 4 factorial scheme, which corresponded to five ECw levels (0.15, 1.5, 2.5, 3.5 and 4.5 dS m) and four N levels (60, 80, 100 and 120 kg ha), with three replicates and 30 plants per plot. The interaction between water salinity levels and N did not have significant effects on the studied variables; irrigation water salinity had isolated negative effects on the total number of achenes, number of viable achenes, productivity and oil yield of achenes. The increase in N levels stimulated the total number and the number of viable achenes, the mass of 1,000 achenes, capitulum diameter and productivity of achenes of sunflower, cv. „Embrapa 122-V2000‟, but had no effect on the oil content of achenes. N levels of up to 100 kg ha promoted adequate oil content in the achenes of sunflower, cv „Embrapa 122-V2000‟.

Substrates and time intervals of renewal of wastewater in production and post-harvest of the ornamental sunflower

A producao de flores em sistema semi-hidroponico e uma alternativa rentavel para geracao de renda em comunidades de agricultores familiares do semiarido brasileiro, isto porque este sistema de cultivo equaciona aspectos ligados ao clima, a agua e ao solo desta regiao, favorecendo a producao das culturas. Neste trabalho estudou-se a utilizacao da agua residuaria como fonte de agua e nutrientes renovado em quatro intervalos de tempo (diariamente, a cada dois, tres e quatro dias) e tres substratos de cultivo (fibra de coco, areia e bagaco de cana de acucar) na producao e pos-colheita de flores de girassol; estes tratamentos foram distribuidos em um delineamento inteiramente casualizado, analisado em esquema fatorial 4 x 3, com tres repeticoes, totalizando 36 unidades experimentais. Verificou-se que as plantas sob renovacao da agua residuaria a cada quatro dias apresentaram caracteristicas compativeis com o padrao comercial para flores de girassol, desde que cultivadas em fibra de coco ou areia.