Nutrient contents and production of rocket as affected by nitrogen concentrations in the nutritive solution

Abstract

Empiricism in the use of nutrient solutions is frequent. Several times the same nutrient solution is used to grow different species based only on morphological similarities. This practice may lead to nutritional imbalances, affecting not only the production but also the quality of the product due to an accumulation of nitrate. An experiment under hydroponic conditions -the NFT system -was conducted with the aim of evaluating the effect of the concentration of nitrogen in the nutrient solution on the production and on the nutrient and nitrate contents of rocket (Eruca sativa) salad leaves. The experiment was carried out in spring 2003, in a randomized block design and in a 4 × 3 factorial design, with four replicates. Four nitrogen concentrations in the nutrient solution (60.8; 121.6; 182.5; 243.5 mg L -1 ) and three rocket salad cultivars (Cultivada, Folha Larga and Selvática) were evaluated. Cv. Cultivada produced the tallest plants and the highest leaf fresh fitomass, not differing from cv. 'Folha Larga' in the number of leaves, leaf nitrate content, root dry fitomass and root fresh fitomass. An increment in NO 3 -, N, Ca and P and a reduction in Mg, K and S occurred when the concentration of N in the nutrient solution was increased. Cultivation of cv. Cultivada at the concentration of 93 mg L -1 is the most recommended as it provides the highest yield and low nitrate content. Key words: Eruca sativa, Diplotaxis tenuifolia, hydroponic system, cultivar, mineral nutrition TEORES DE NUTRIENTES E PRODUÇÃO DE RÚCULA EM FUNÇÃO DAS CONCENTRAÇÕES DE NITROGÊNIO EM SOLUÇÃO NUTRITIVARESUMO: O empirismo no uso das soluções nutritivas é freqüente. Muitas vezes a mesma solução nutritiva é usada para diferentes espécies baseando-se apenas em semelhanças morfológicas. No entanto esta situação pode proporcionar desequilíbrio nutricional prejudicando tanto a produção quanto a qualidade do produto face o acúmulo de nitrato. Foi conduzido um trabalho em sistema hidropônico -NFT, com o objetivo de avaliar o efeito da concentração de nitrogênio na solução nutritiva na produção, nos teores de nutrientes e de nitrato em folhas de rúcula (Eruca sativa). O trabalho foi conduzido na primavera de 2003. Foram avaliadas quatro concentrações de nitrogênio na solução nutritiva (60,8; 121,6; 182,5; 243,5 mg L -1 ) e três cultivares de rúcula (Cultivada, Folha Larga e Selvática), sob delineamento de blocos ao acaso, fatorial 4 × 3, com quatro repetições. A cv. Cultivada apresentou maior estatura e fitomassa fresca de folhas, não diferindo da 'Folha Larga' quanto a número de folhas, teor de nitrato nas folhas e fitomassa seca e fresca da raiz. Houve incremento de NO 3 -, N, Ca e P e diminuição de Mg, K e S com o aumento da concentração de N na solução nutritiva. O cultivo da cv. Cultivada na concentração de 93 mg L -1 é a mais recomendada em função da maior produtividade e baixo teor de nitrato.

Genetic variability for mineral concentration of Eruca sativa L. and Diplotaxis tenuifolia L. accessions

“…In this study, Mg concentration varied among genotypes with an average concentration of 0.57 mg g -1 . Kawashima and Valente-Soares (2003) reported that E. sativa Mg concentration was 0.30 mg g -1 , and Cavarianni et al (2008) 0.43-0.46 mg g -1 which are very similar to our findings. Mineral concentrations can differ across tissues within a single plant, across genotypes of a given species, or more broadly across species (Arzani et al 2007).…”

Desempenho de cultivares de rúcula sob soluções nutritivas com diferentes salinidades.

“…Estes resultados divergem dos obtidos por Cavarianni et al (2008), que observaram maior altura para a cultivar Cultivada. No entanto, Linhares et al (2011) trabalhando com essas cultivares na região de Mossoró, em condições de campo, não observaram diferença significativa para altura das plantas.…”

Productivity, nutritional and functional qualities of perennial wall-rocket: Effects of pre-harvest factors

“…Alberici et al (2008) found that the leaf nitrate content of rocket was affected neither by the crop season nor by nutrient solution EC (2,800 mg kg -1 FW on average). When the nutrient film technique was used, leaf nitrate concentration was highest (2,410 mg kg -1 FW) under 244 mg N L -1 and 2.5 dS m -1 EC (Cavarianni et al, 2008). The cultivar 'Selvática' showed the highest nitrate content (1,859 mg NO 3 kg -1 FW) in comparison with 'Folha Larga' and 'Cultivada' (1,035 mg NO 3 kg -1 FW on average).…”

“…Using the nutrient film technique, the highest perennial wall-rocket yield (12.5 t ha -1 ) was obtained with 122 mg dm -3 N and with an electrical conductivity (EC) of 2.2 dS m -1 (Cavarianni et al, 2008); moreover, the cultivar 'Cultivada' produced the highest yield (16.9 t ha -1 ), followed by 'Folha Larga' and finally 'Selvática' (12.3 and 2.9 t ha -1 , respectively). Bonasia et al (2017) reported that in the autumnwinter cycle the increase in nutrient solution concentration from 2.5 to 3.5 dS m -1 EC caused a significant reduction in leaf fresh yield (-18.7%), whereas in the winter-spring growing cycle, increasing the EC of the nutrient solution from 3.5 to 4.5 dS m -1 resulted in a milder reduction in fresh leaf yield (-10.3%).…”