Nutritive solution application discharge, lettuce nitrate content on hydroponic cultivation and sensorial acceptability

O presente estudo buscou avaliar influÃncia das vazÃes de aplicaÃÃo da soluÃÃo nutritiva na produÃÃo e acÃmulo de nitrato em folha de alface (Lactuca sativa L) cultivado sob sistema hidropÃnico do tipo NFT e aceitabilidade sensorial entre os sistemas de cultivo: hidropÃnico, convencional e orgÃnico. O delineamento estatÃstico foi o inteiramente casualizado com trÃs tratamentos e oito repetiÃÃes. Os tratamentos foram compostos de uma soluÃÃo nutritiva em trÃs vazÃes de aplicaÃÃo (0,5, 1,0 e 1,5 L.min-1). No perÃodo de 14/06/06 a 12/07/06 em Cascavel Estado do ParanÃ. A colheita foi realizada aos 28 dias pÃs-transplante. Os dados foram analisados estatisticamente, utilizando-se anÃlise de variÃncia (Teste F) e teste de Tukey (5%). As caracterÃsticas avaliadas foram: biomassa fresca e seca total, da parte aÃrea, da raiz, do caule. NÃmero de folhas: total, aproveitÃveis e nÃo aproveitÃveis. DiÃmetro e comprimento do caule. A vazÃo que proporcionou os melhores resultados foi a de 1,5 L.min-1. Em relaÃÃo ao teor de nitrato nÃo ocorreram diferenÃas significativas, ao nÃvel de 5% de significÃncia. As condiÃÃes organolÃpticas foram analisadas pela escala hedÃnica de nove pontos. As amostras eram provenientes de trÃs sistemas de cultivo: hidropÃnico, convencional e orgÃnico e os tratamentos foram os sistemas de cultivos e as repetiÃÃes foram porÃÃes de, aproximadamente, 20 g de alface de cada um dos sistemas. Pelos resultados encontrados pode-se concluir anÃlise de variÃncia pelo teste de Tukey a 5%, apontando diferenÃas significativas entre os parÃmetros analisados como: aparÃncia, sabor, textura, cor e qualidade global, nÃo apresentando diferenÃas significativas quanto ao atributo aroma. O sistema orgÃnico apresentou a melhor mÃdia, considerando a qualidade global 7,6, aproximando-se da categoria gostei muito. O cultivo hidropÃnico apresentou mÃdia 7,5, aproximando-se, tambÃm, da categoria gostei muito. Apresentou-se sempre como melhor a produÃÃo orgÃnica, seguida da hidropÃnica, em que nÃo ocorreram diferenÃas significativas na maioria dos atributos entre os dois cultivos, porÃm ocorreram diferenÃas significativas, para o cultivo convencional, ficando sempre em Ãltimo lugar na preferÃncia dos consumidores.This study objective was to evaluate letuce (Lactuca sativa L cv. Vera) production and nitrate acumulation on its foliage under an environment protected by the Nutrient Film Technique (NFT) hidroponic system due to discharge of nutritive solution aplication and sensorial acceptability among conventional, organic, and hidroponic systems. Treatment was made of nutritive solutions combinned with three discharge aplications on the cultivated channels. Nutrient Solution was prepered according to FURLANI et al. (1999) which presents electric conductivity of 1.2 ms.cm. Aplication discharge were 0,5, 1,0 e 1,5 L.min-1. To evaluate the effect of treatments in the developing of the culture, data was submited to variance analisys (F test), and the results were evaluated through Tukeyâs average test (5%). Statistical delineament was casual with three treatments and eight repetitions. Each experimental unit comprised of eight heads of lettuce totaling 192 analized plants. Total fresh biomass, aereal fresh biomass, root fresh biomass, trunk fresh biomass, total dry biomass, aereal dry biomass, root dry biomass, and trunk dry mass were the evaluated caracteristic. It was concluded that the best discharge was 1.5 L.min-1, followed by 1.0 L.min-1 and last 0.5 L.min-1. As for nitrate ammount, analisys was done through spectrophotometry with samples of a plant for each analisys, and then avarege was taken between both analyses. There was no important differences to the level of 5% of significance. Organoleptic conditions were analized by the hedonic scale. Samplings originated from three cultivation systems: hidrophoinoc conventional and organic. Treatment was the three diferent culture systems, and repetirions were portions of aproximatly 20g of letuce from each system. Sensorial analysis results were interpreted through a variance analysis and an average comparison by the Tukey test showing the significant differences between the analyzed parameters such as appearance, flavor, texture, color, and global quality, but it did not present significant difference on the scent attribute. The organic system showed the best average considering global quality of 7.6, approximating the category âLiked a lot.â The hydroponic cultivar showed an average of 7.5, which also approximate the category âLiked a lot.â The organic method showed to be the best followed by the hydroponic method, where there were no significant difference in most attributes between the two cultivars, however, there were important differences to the 5% level of significance placing soil cultivation in last on consumer preference âScent.