Current technology of pineapple micro-propagation has problems with the plants transition to field, these problems are associated to drastic changes of environmental conditions linked to poor hardening plant for such transit. A possibility of preparation is the induction of defense mechanisms to drought stress and get modulating CAM, so that the object of this paper was study plants grown for 30 days in two water status (well-watered plants and non-watered plants) after 30 days both groups were full-watered during 15 days. Measurements were made on D-leaf, in which were determinates the gas exchange, water-efficiency use (WEU), night CO2 uptake percentage, chlorophyll content, organic acids levels, succulence index (IS) and superoxide dismutase activity (SOD) (EC 1.15.1.1). After 15 days of drought, plants had the best response to field transfer, with increase in CAM expression, supported by the decline in total chlorophyll content and increases in the night CO2 uptake percentage, WEU, SI, and SOD activity. After 30 days of drought plants had a CAM strong response, with 100 % of CO2 uptake during night, but its rapid recovery with the establishment of irrigation to saturation of the substrate, showing high drought tolerance and great metabolic plasticity

La tecnología actual de micropropagación de piña presenta problemas con la transición de las plantas al campo, dichos problemas se asocian al drástico cambio de las condiciones ambientales unido al pobre endurecimiento de las plantas para su tránsito. Una posibilidad de su preparación es la inducción de mecanismos defensivos mediante el déficit hídrico y consigo la modulación de CAM (Metabolismo Ácido de las Crasuláceas, siglas en inglés) por lo que en este trabajo se estudiaron plantas crecidas durante 30 días en dos regímenes hídricos (plantas con riego y sin riego), después de este momento ambos grupos se regaron hasta la saturación del sustrato durante 15 días. Las determinaciones se realizaron en la hoja “D” con frecuencia quincenal. Se determinó el intercambio gaseoso, eficiencia en el uso del agua (EUA), porcentaje de captación de CO2 en la noche, contenido de clorofilas, niveles de ácidos orgánicos, índice de suculencia (IS) y actividad de superóxido dismutasa (SOD) (EC 1.15.1.1). A los 15 días las plantas sin riego tuvieron la mejor respuesta para su traslado a campo, con el aumento de la expresión de CAM, sustentado por la disminución del contenido de clorofilas totales y por el incremento del porcentaje de asimilación de CO2 durante la noche, EUA, IS y actividad SOD. A los 30 días las plantas sin riego tuvieron una respuesta CAM de mayor intensidad, con el 100 % de captación de CO2 durante la noche, pero su rápida recuperación con el establecimiento del riego hasta la saturación del sustrato, lo cual demostró alta tolerancia a la sequía y elevada plasticidad metabólica

Pineapple (Anana comosus (L.) Merr.) is a species of high commercial demand, MD-2 is among the most promising varieties, which has captured the consumer appeal in recent years. For this reason micro-propagation techniques are used to achieve plants with better agronomic traits and seed production of excellent quality. In Cuba, although there have been some attempts to introduce the plantlets under production conditions of State Entities and Agricultural Enterprise, for various reasons the goal has not successfully been achieved. For this reason, we began working introducing vitroplants of pineapple MD-2 in collaboration with selected farmers and their families with a view to establishing agro-technics that allow to have an alternative planting material, procedures, necessary for productive reanimation pineapple cultivation and develop the technological basis to ensure continuous generation of planting material needed to maintain varietal biodiversity strategies and according to market demand. The results achieved to date demonstrate higher survival rates in vitro plants (90 %) during the first three months of field evaluation. The agrotechnic management established, allowed the increase of all variables evaluated in vitro plants (No. of leaves, No. of roots, length of major root and ¨D¨ leaf width, fresh mass and length of plant) tested in field conditions. It was also shown by bromatology analyzes, done to the fruits that they comply with such attributes internationally for pineapple MD-2 and that the agrotechnics applied to this crop influenced the results achieved

La piña (Anana comosus (L.) Merr.) es una especie de gran demanda comercial, entre las variedades más promisorias se encuentra la MD-2 la cual ha acaparado la atracción del consumidor en los últimos años. Por esta razón se emplean las técnicas de micropropagación para lograr plantas con mejores caracteres agronómicos y producir semillas de excelente calidad. En Cuba, aunque se han realizado algunos intentos de introducir las vitroplantas bajo las condiciones de producción de Entidades Estatales y Empresas Agrícolas, por diversas causas no se ha logrado satisfactoriamente este objetivo. Por esta razón, se comenzó a trabajar la introducción de vitroplantas de piña MD-2 con la colaboración de campesinos seleccionados y sus familiares, con vista a establecer procedimientos agro-técnicos que permitan contar con un material de siembra alternativo, necesario para la reanimación productiva del cultivo de la piña y así desarrollar las bases tecnológicas para garantizar la generación continua del material de siembra necesario para mantener las estrategias varietales, acorde a la biodiversidad y exigencia del mercado. Los resultados alcanzados hasta la fecha demuestran que se logran altos porcentajes de supervivencia en las vitroplantas (90 %) durante los primeros tres meses de evaluación en campo. El manejo agro-técnico que se estableció, permitió el incremento de todas las variables evaluadas en las vitroplantas (número de hojas, número de raíces, longitud de la raíz mayor, longitud y ancho de la hoja ¨D¨, masa fresca y longitud de la planta) en las condiciones de campo ensayadas. También se pudo demostrar, por análisis bromatológicos realizados a los frutos, que éstos cumplen con las características descritas internacionalmente para la piña MD-2 y que las atenciones agrotécnicas realizadas al cultivo influyeron en los resultados

Os países produtores do abacaxi precisam de mudas de boa qualidade para a introdução de novas culturas nas áreas de cultivo. Os protocolos de pesquisa podem aumentar a oferta de mudas de alta qualidade e acelerar a introdução de novas culturas do abacaxi. O estudo apresentado teve como objetivo avaliar as alterações morfofisiológicas de mudas de abacaxi [Ananas comosus (L.) Merr. 'MD-2'], durante a fase de aclimatação. As plantas foram aclimatizadas baseadas em um regímen de 80% de humidade relativa, uma temperatura de 25°C e um fluxo médio de fótones fotossinteticamente ativos de 400-500 µmol m-2 s-1, durante 45 dias em condições naturais de iluminação. As medições todas (comprimento da planta, número de folhas, comprimento, largura da folha maior 'D', taxa fossintetica e taxa transpiratória total) foram feitas no final da fase do enraizamento in vitro a coincidir com a aclimatização no período de 0, 15, 30 e 45 dias após aclimatização. Depois de 30 dias, a atividade fotossintética variou entre 5,72 e 9,36 µmol CO2 m-2 s-1, enquanto a transpiração total variou de 6,0 a 1,42 mmol H2O m-2 s-1. Durante os primeiros 30 dias, não foram registradas diferenças significativas entre o e comprimento da planta, número de folhas e comprimento e largura da folha maior 'D'. No entanto, após 45 dias a massa fresca da planta (g), comprimento e largura da lâmina 'D' (cm) e o número de raízes aumentarem significativamente, enquanto a transpiração (mmol H2O m-2 s-1) foi reduzida. As clorofilas a e b (µg g-1 mf) diminuíram e mostraram diferenças pequenas, mas significativas. O aumento da atividade fotossintética após 30 dias mostrou que o aumento da intensidade luminosa e redução da umidade relativa não são fatores inibidores desta atividade durante a aclimatização.

Pineapple producing countries lack good quality propagation material to expand cultivars into new areas. Previously, research protocols may increase the offer of high quality plantlets and speed the introduction of new pineapple cultivars. The present work is to evaluate the morpho-physiological changes in plantlets of pineapple [Ananas comosus (L.) Merr. 'MD-2'] during the acclimatization phase. Plantlets were acclimatized under 80% relative humidity, 25.5 °C temperature and photosynthetic photon flux of 400-500 µmol m-2 s-1 as average for 45 d under natural photoperiods. All measurements (plant length, number of leaves and roots, fresh weight, width and length of leaf 'D', net photosynthesis and total transpiration rate) were carried out at the end of in vitro rooting phase coincident with 0 d of acclimatization and at 15, 30 and 45 d thereafter. Photosynthetic activity of in vitro plantlets did not increase during the first 30 d of the acclimatization phase. After 30 d, photosynthetic activity ranged from 5.72 to 9.36 µmol CO2 m-2 s-1 while total transpiration ranged from 6.0 to 1.42 mmol H2O m-2 s-1. During the first 30 days there were no significant differences in number of leaves, length or width of the longest ('D') leaf (cm) or plant length (cm). However, after 45 days plant fresh weight (g), length and width of the 'D' leaf (cm) and root number all increased significantly, while transpiration (mmol H2O m-2 s-1) declined. There were small but significant decreases in chlorophyll a and b (µg g-1 mf.). Increased photosynthetic activity after 30 d shows that the increase in light intensity and the reduction of relative humidity during acclimatization did not constitute inhibitory factors.