Effects of the concentration of nutrient solution on lettuce growth in hydroponics-NFT system

Nitrogen compounds and soluble sugars in tissues of organic, hydroponic, and conventional lettuce

No abstract

Ao Deus todo poderoso e criador das nossas vidas, pela presença constante no meu coração, por guiar meus passos neste caminho, tão árduo e pela família maravilhosa que me concedeu. OFEREÇO Aos meus pais, Walter e Juracy, uma dádiva de Deus para minha vida, pela fé e esperança com que acreditaram na realização deste grande sonho, por toda demonstração incondicional de amor e carinho. Aos meus irmãos, Reginaldo, Edcarlos e Kênia Cíntia, mesmo que distantes pelo incentivo e companheirismo em todos os momentos. Aos meus avós, carinhosamente chamados de "Dindinho e Dindinha" grandes motivadores da minha carreira profissional. A minha tia, Edna, pela ajuda nos momentos mais difíceis, nunca mediu esforço para colaborar com minha formação acadêmica. A Karina Batista pelo carinho, compreensão e presença continua nesta fase da vida. DEDICO A uma grande amiga Alline Campos, pelas as palavras de incentivo e motivação.

2 Calcium (Ca) and boron (B) have been reported as the major macro-and micronutrient required for castor bean plant yield. The objective of this study was to determine the Ca:B ratios (in the growth media and plant tissue) for fruit yield and shoot dry weight of the castor bean (Ricinus communis L.), grown in a nutrient solution, and to evaluate Ca and B supply on concentration and total uptake of Ca, potassium (K), magnesium (Mg), and B, as well on the seed oil content. The treatments were arranged in a 3 × 3 factorial fashion, consisting of three rates of Ca (40, 80, and 160 mg L −1 ) and three of B (0.32, 0.96, and 1.60 mg L −1 ). Calcium and B rates increased the shoot and root dry weight and fruit yield at a Ca:B ratio in the nutrient solution of 166 and 100, respectively. Symptoms of B deficiency were observed in plants supplied with 0.32 mg B L −1 , regardless of the Ca concentration in the nutrient solution. Plants which showed visual symptoms of Ca deficiency cultivated with 40 mg Ca L −1 presented concentration of Ca in plant tissue up to 10 g kg −1 . The concentration and total Ca and B uptake increased with the rates of them. Notwithstanding, the shoot Ca accumulation was improved by B rates. In addition, there were no decreases in K and Mg uptake due to Ca rates. Furthermore, addition of 80 mg L −1 of Ca and 1.60 mg L −1 of B in the growth media increased the seed oil content. The Ca:B ratio in the diagnostic leaf associated with the highest plant dry weight (shoot and root) and fruit yield, was 500 (16 to 20 g kg −1 of Ca, and for 30 to 40 mg kg −1 of B).