Agronomic and sensory evaluation of lettuce in hydroponic system

Lettuce is the most important leafy vegetable in Brazil. Hydroponic lettuce cultivation has grown due to the viability of harvesting throughout the year. In this context, this study aimed to evaluate the agronomic characteristics, color, and preference of curly lettuce in the NFT hydroponic system. Six lineages (6601-1A, 6601-2L, 7016-6A, 7119-1B, 7223-1A, and 7224-4A) and two commercial cultivars (Brida and Vanda) of lettuce were used, in a completely randomized blocks design with four replications. Shoot length, root length, stem length, number of leaves, stem diameter, plant diameter, shoot fresh mass, root fresh mass, chlorophyll content, instrumental color, and sensory characteristics were evaluated. As for agronomic evaluation, the bolting of 6601-2L lettuce was relevant in different attributes. The Vanda lettuce and the lineage 7016-6A presented best performances for shoot fresh mass (399.44 and 378.63 g, respectively), while the lineages 7119-1B and 6601-2L present the worst performance (279.50 and 273.13 g, respectively). There was variation in chlorophyll content and luminosity, however, the evaluators did not notice differences between lettuces for brightness or green color, as well as for crunchy texture. Lettuces 6601-2L, 7224-4A, 6601-1A, Brida, 7223-1A, and 7119-1B were preferred. The variation among plants may be due to different situations, such as harvesting times and bolting, and a direct relationship between agronomic properties and preference among lettuces has not been established yet.

Effect of phosphorus on arsenic uptake and metabolism in rice cultivars differing in phosphorus use efficiency and response

ABSTRACT A hydroponic experiment was carried out to investigate the effect of phosphorus (P) nutrition on arsenic (As) uptake and translocation within the seedlings of rice cultivars. The experiment occurred in three stages: I 5 days of acclimatization (nutritive solution); II 10 days under P (0.0 and 0.09 mM) and As (0.0 and 100 mM) treatments; III 5 days under recovery. The As exposure had significant effect reducing dry weights of shoots or roots, resulted in elevated concentrations of As in shoot tissues. BR-IRGA 409 showed the highest susceptibility to As in biomass production and root system parameters regardless the P level. This cultivar showed contrasting responses of As translocation to shoot tissue dependent on P levels, with the highest As concentration under low P and lowest under normal P levels. P nutrition was most striking on plants recovery for all cultivars under As exposure. Clearer separation of cultivars for phosphorus use efficiency (PUE) occurred at lower shoot P contents, that was, at higher levels of P deficiency stress. IRGA 424 showed higher PUE as compared to the others cultivars. Our results go some way to understanding the role of P nutrition in controlling the effects of As in rice shoots.

La irrigación con levaduras incrementa el contenido nutricional del forraje verde hidropónico de maíz / Yeast irrigation enhances the nutritional content in hydroponic green maize fodder

El objetivo del presente estudio fue evaluar el efecto de la irrigación con las levaduras Debaryomyces hansenii var. Fabry, Yarowia lipolytica YIBCS002, Yarowia lipolytica var. BCS y Candida pseudointermedia sobre el contenido nutricional final del forraje verde hidropónico de maíz (Zea mays L. ), al ser efectuada en diferentes etapas de crecimiento de aquel (fase semilla-plántula o fase plántula-planta 20 cm), o bien durante todo el cultivo. Todas las levaduras incrementaron el contenido de proteína cruda, lípidos, cenizas, humedad y energía bruta, independientemente de la etapa de crecimiento del forraje en las que fueron aplicadas. El porcentaje de electrólitos (Na, K, Cl, sulfatos, Ca y Mg) varió en función de la levadura aplicada; D. hansenii incrementó todos los electrólitos, excepto el P. Se concluye que la adición de levaduras del género Debaryomyces, Candida y Yarowia en la solución de riego de sistemas hidropónicos mejora el contenido de nutrientes del forraje verde. Esta práctica puede contribuir a la generación de cultivos de valor comercial en espacios limitados

The objective of this study was to evaluate the effect of irrigation with yeasts (Debaryomyces hansenii var. Fabry, Yarowia lipolytica YIBCS002, Yarowia lipolytica var. BCS and Candida pseudointermedia) on the final nutritional content of hydroponic green maize fodder (Zea Zea mays L.), applied at different fodder growth stages (1. seed-seedling stage, 2. seedling-plant 20 cm, 3. during all the culture). Irrespective of the fodder growth stages at which they were applied, all yeasts tested enhanced the content of raw protein, lipids, ash, moisture and energy. The percentage of electrolytes (Na, K, Cl, sulphates, Ca and Mg) showed different responses depending on the kind of yeast applied; D. hansenii exhibited the highest increment in all electrolytes, except for phosphorous. We conclude that the addition of yeasts belonging to the genera Debaryomyces, Candida and Yarowia to the irrigation solution of hydroponic systems enhances the nutrient content of green fodder. This kind of irrigation can be applied to generate high commercial value cultures in limited spaces.

Phosphorus amendment competitively prevents chromium uptake and mitigates its toxicity in Spinacea oleracea L.

In this study, we assessed the role of phosphorus in preventing chromium uptake by plants. Two-factor complete randomized pot experiment (5x5 pattern) was conducted hydroponically with Spinacea oleracea L. (spinach), for 28 days in green house. Five concentrations of Cr (2.0, 3.5, 5.0, 6.5 and 8.0 mM), each amended with five concentrations of phosphorus (25, 50, 75, 100 and 125 mM) were supplied. With the phosphorus amendment in the growth medium, accumulation of chromium decreased up to 55% in root and 50% in shoot tissues. A 1.8-fold enhancement in total chlorophyll and 2-fold increase in the biomass of root and shoot were observed due to phosphorus amendment. Levels of superoxide dismutase, catalase, peroxidase and malondialdehyde were reduced by 27, 11.7, 38.1 and 45.5% in root tissues; and 27, 17.4, 32.3 and 35.1%, in shoot tissues, respectively. In conclusion, the phosphorus amendment has been shown not only to moderate the Cr-toxicity in S. oleracea but also enrich chlorophyll content as well as the biomass.

In vitro propagation of the Garden Heliotrope, Valeriana officinalis L.: Influence of pre-chilling and light on seed germination.

Valeriana officinalis is an important medicinal herb commonly found in Kashmir valley. This study forms an important preliminary step for in-vitro micro propagation of V. officinalis from breaking the seed dormancy, inducing rapid seed germination and its subsequent micro propagation. We investigated the influence of pretreatment of V. officinalis seeds with reduced temperature and light on seed germination and in-vitro propagation. Culture of explants from cultivated seeds have demonstrated its potential for in vitro propagation and plantlet regeneration. Individual as well as combinations of treatments such as temperature and light availability influenced the germination of seeds variedly. Unchilled seeds of V. officinalis were given dip in GA3 (200 ppm) for 24, 48 and 120 h. Seeds treated with GA3 for 24 h and kept in darkness showed the best results, i.e. 48%. Seeds pretreated with GA3 for 120 h and incubated in dark showed 40% germination. Pre-chilling up to 72 h and kept in light showed maximum germination of 60% followed by 40% kept in darkness. Pre-chilling for 48 h resulted in 40 and 25% seed germination in light and darkness, respectively. GA3 pre-treatment for 72 h and 24 h pre chilling were most effective in inducing seed germination. Maximum shoot response was obtained on MS enriched with BAP (1mg/L) + IAA (0.1mg/L) combinations using shoot tips as explants. Multiple shoot regeneration from shoot apices was recorded on BAP (1mg/L) and BAP (1mg/L) + IAA (0.1mg/L).

Recipientes e substratos na produção de mudas e no cultivo hidropônico de tomilho (Thymus vulgaris L. ) / Containers and substrates on seedling production and hydroponic cultivation of thyme (Thymus vulgaris L. )

Bandejas com diferente número de células (128, 200 e 288) e dois substratos (fibra de casca de coco e casca de pinus) foram avaliados para a produção de mudas de tomilho e sobre o desempenho das plantas em sistema hidropônico. Para ambos os experimentos, o delineamento foi em blocos ao acaso. As mudas provenientes de estaquia foram avaliadas aos 30 dias quanto ao comprimento e massa seca de raízes. Aos 40 dias após o transplante das mudas, as plantas cultivadas em sistema hidropônico foram avaliadas quanto à massa fresca da parte aérea, massa seca da parte aérea e massa seca das raízes. A maior massa seca de raízes foi obtida para as mudas cultivadas em substrato à base de casca de fibra de coco. As mudas com maior comprimento de raízes foram obtidas nas bandejas com 128 e 200 células. As plantas de tomilho provenientes de mudas produzidas em bandejas de 128 células apresentaram maior massa fresca da parte aérea, massa seca da parte aérea e massa seca das raízes.

Trays with different number of cells (128, 200 and 288) and two substrates (coir and pine bark-based) were studied for thyme seedling production and plant development in hydroponic system. In both experiments, experimental design was in randomized blocks. Seedlings from cuttings were evaluated at 30 days as to root length and dry matter. At 40 days after transplanting, plants grown in hydroponic system were evaluated for shoot fresh matter, shoot dry matter and root dry matter. The highest root dry matter was detected in seedlings grown in coir-based substrate. Seedlings that presented the greatest root length were obtained by using trays with 128 and 200 cells. Thyme plants from seedlings produced in trays with 128 cells had higher shoot fresh matter, shoot dry matter and root dry matter.