Influence of cultivation medium on growth of tissue cultured seedlings of Polygonatum cyrtonema / 中草药

Objective: To find a solution to the problems in the growth of tissue cultured seedlings of Polygonatum cyrtonema, such as low seedling survival rate, poor growth, and leaf disease. Method: In this study, tissue cultured seedlings of P. cyrtonema were used as testing plants. Two types of commercially-available cultivation medium commonly used in Fujian Province, as well as six types of cultivation medium mixed using peat soil, pearlite, roseite, sand, fungi residues and plant ash were used as the raw materials; Among them, a customized nutrient solution was added into the T5 and T7 cultivation media. Besides measuring the physicochemical properties of the cultivation media mentioned above, the study focused on the evaluation of their influence on the rate of grown-up seedlings, biological characteristics, growth biomass, strength index and incidence of leaf disease of P. cyrtonema. It also attempted to find the correlation between the physicochemical properties of the cultivation media and the biological characteristics, growth biomass, as well as the strength index of tissue cultured seedlings of P. cyrtonema. Results: The difference in the cultivation media had a great influence on the tissue cultured seedlings of P. cyrtonema in the rate of grown-up seedlings, biological characteristics, growth biomass, strength index and incidence of leaf disease. The difference in bulk density of the cultivation media had a notable negative correlation with the plant height of the tissue cultured seedlings of P. cyrtonema. The difference in the organic content of the cultivation media had a notable positive correlation with the fresh weight and dry weight of the tissue cultured seedlings of P. cyrtonema. Treated with the T5 cultivation medium we prepared, the tissue cultured seedlings of P. cyrtonema were in better growing condition in the rate of grown-up seedlings, morphological index, growth bomass, strength index, and no disease was found on the leaf. Conclusion: The prepared T5 was worth being widely used as the cultivation medium for growth of tissue cultured seedlings of P. cyrtonema.

Post-seminal structure and development of the hemiparasitic plant Escobedia grandiflora (Orobanchaceae)

Escobedia grandiflora(L.f.) Kuntze is a wild hemiparasitic plant with orange roots. Little is known about the development of initial parasitism with the host, despite the significant value of roots for Central and South American communities. Therefore, this study aimed to characterize post-seminal structure and development of E. grandiflorain Pennisetum purpureumhost. To analyze the structure and development of E. grandiflora, seedlings, stems and roots samples were processed and examined underlight, confocal and scanning electron microscopy. Escobedia grandifloraseeds are composed of seed coat, perisperm, and embryo. Emergence of the radicle began eleven days after imbibition. Seedlings showed a root hair collar encircling the axis at the root-hypocotyl junction with elongation of internal cortical cells. Seedlings formed haustoria and successfully reached of the host roots 22 days following root emergence. In the root many starch grains were observed, albeit more scarce in the hypocotyl. After 43 days of root emergence, the seedling stage was finished with the formation of the definitive leaves, and star of the plant stage. After 64 days, root ramification, amount of starch, and orange pigmentation increased with formation of haustoria. The developmental pattern of E. grandiflora plants was slow, but the roots grew faster than the stem. Escobedia grandifloraseeds were not endospermic and have limited nutritional value. After root emergence, the young seedling must develop roots and starch storage towards to haustorium formation and attachment to host roots.

Screening of Rice Genotypes for Thermotolerance BY TIR Technique.

Production of rice--the world's most important crop for ensuring food security and addressing poverty will be defeated as temperatures increase in rice-growing areas with continued climate change. Climate change needs us to look at various alternatives for more drought tolerant and tougher strains and to develop a technique to screen a large number of genotypes for high temperature tolerance. Adapting temperature induction response (TIR) technique 100 rice genotypes were screened for thermotolerance. Significant variation for acquired thermotolerance was observed in 100 rice lines. From the 100 genotypes 30 were exhibits themotolerance to induced high temperature.

Factors affecting establishment success of the endangered Caribbean cactus Harrisia portoricensis (Cactaceae)

Early plant stages may be the most vulnerable within the life cycle of plants especially in arid ecosystems. Interference from exotic species may exacerbate this condition. We evaluated germination, seedling survival and growth in the endangered Caribbean cactus Harrisia portoricensis, as a function of sunlight exposure (i.e., growing under open and shaded areas), different shade providers (i.e., growing under two native shrubs and one exotic grass species), two levels of predation (i.e., exclusion and non-exclusion) and variable microenvironmental conditions (i.e., temperature, PAR, humidity). Field experiments demonstrated that suitable conditions for germination and establishment of H. portoricensis seedling are optimal in shaded areas beneath the canopy of established species, but experiments also demonstrated that the identity of the shade provider can have a significant influence on the outcome of these processes. Harrisia portoricensis seedlings had higher probabilities of survival and grew better (i.e., larger diameters) when they were transplanted beneath the canopy of native shrubs, than beneath the exotic grass species, where temperature and solar radiation values were on average much higher than those obtained under the canopies of native shrubs. We also detected that exclusión from potential predators did not increase seedling survival. Our combined results for H. portoricensis suggested that the modification of microenvironmental conditions by the exotic grass may lower the probability of recruitment and establishment of this endangered cactus species. Rev. Biol. Trop. 60 (2): 867-879. Epub 2012 June 01.

Las etapas iniciales de las plantas parecen ser las más vulnerables de su ciclo de vida, especialmente en ecosistemas áridos. Interferencias de especies exóticas pueden exacerbar esta condición. Evaluamos la germinación, supervivencia y crecimiento de plántulas del cactus en peligro de extinción Harrisia portoricensis, en función de la exposición a la luz solar, diferentes proveedores de sombra, exclusión de potenciales depredadores y condiciones micro-ambientales variables. Los experimentos demostraron que las condiciones adecuadas para la germinación y el establecimiento de plántulas de H. portoricensis son óptimas en áreas de sombra, bajo el dosel de especies establecidas, pero también demostraron que la identidad de los proveedores de sombra puede tener una influencia significativa sobre los resultados de estos procesos y que la exclusión de depredadores no aumentó la probabilidad de supervivencia de las plántulas. Las plántulas de H. portoricensis tuvieron mayores probabilidades de supervivencia y crecieron mejor cuando fueron transplantadas bajo la sombra de los arbustos nativos que bajo la sombra del pasto exótico, donde la temperatura y la radiación solar fueron en promedio mucho mayores que las obtenidas bajo la sombra de los arbustos nativos. Nuestros resultados sugieren que las modificaciones de las condiciones micro-ambientales por este pasto exótico pueden disminuir la probabilidad de reclutamiento y establecimiento de esta especie en peligro.

Phenology, seed dispersal and difficulties in natural recruitment of the canopy tree Pachira quinata (Malvaceae)

Life history and recruitment information of tropical trees in natural populations is scarce even for important commercial species. This study focused on a widely exploited Neotropical canopy species, Pachiraquinata (Malvaceae), at the southernmost, wettest limit of its natural distribution, in the Colombian Amazonia. We studied phenological patterns, seed production and natural densities; assessed the importance of seed dispersal and density-dependent effects on recruitment, using field experiments. At this seasonal forest P. quinata was overrepresented by large adult trees and had very low recruitment caused by the combination of low fruit production, high seed predation and very high seedling mortality under continuous canopies mostly due to damping off pathogens. There was no evidence of negative distance or density effects on recruitment, but a clear requirement of canopy gaps for seedling survival and growth, where pathogen incidence was drastically reduced. In spite of the strong dependence on light for survival of seedlings, seeds germinated readily in the dark. At the study site, the population of P. quinata appeared to be declining, likely because recruitment depended on the rare combination of large gap formation with the presence of reproductive trees nearby. The recruitment biology of this species makes it very vulnerable to any type of logging in natural populations. Rev. Biol. Trop. 59 (2): 921-933. Epub 2011 June 01.

Información acerca de la historia de vida y reclutamiento de poblaciones naturales de árboles tropicales es escasa, incluso para especies de alto interés comercial. Este estudio se centró en una especie de dosel altamente explotada, Pachira quinata (Malvaceae), en la zona más húmeda de su distribución geográfica, en la Amazoní a colombiana. Estudiamos sus patrones fenológicos, producción de semillas y densidades naturales, además de la importancia de la dispersión de semillas y efectos denso-dependientes en el reclutamiento natural, todo lo anterior se logró con el uso de experimentos y observaciones en el campo. En este bosque estacional, la población de P. quinata estaba dominada por grandes árboles adultos y el reclutamiento era extremadamente bajo, como consecuencia de la baja producción de frutos, alta depredación de semillas y muy alta mortalidad de plántulas bajo el bosque por infección de patógenos. No encontramos evidencia de efectos de distancia al árbol parental o densidad de semillas en el reclutamiento, pero si hallamos un evidente requerimiento de claros de luz para la supervivencia y el crecimiento de plántulas, donde la mortalidad por patógenos se reduce drásticamente. Sin embargo, a pesar de la dependencia de la luz para la supervivencia, las semillas germinan en la oscuridad. En la zona de estudio, la población de P. quinata parece estar en claro declive, probablemente porque el reclutamiento depende de la coincidencia de la formación de grandes claros con la presencia cercana de árboles reproductivos. Los requerimientos de reclutamiento de esta especie la hacen muy vulnerable a cualquier actividad extractiva de árboles adultos en poblaciones naturales.

Influence of acorn size and storage duration on moisture content, germination and survival of Quercus petraea (Mattuschka)

This study was conducted to evaluate how acorn size (small, medium and large) and acorn storage duration (0, 5 and 17 months) influenced Quercus petraea (Mattuschka) moisture content and germination. Acorn size and storage duration did not significantly affect acorn moisture content, but they significantly affected acorn germination performance. When averaged for three acorn sizes, loss of germination performance occurred after 17 months of storage even when the moisture content did not reduce significantly and remain at the initial level (32.6%). Maximum germination percentage was observed in large and medium size classes before storage (93 and 95%, respectively) and after 5-month storage (94 and 93%, respectively), but after 17-month storage medium acorn size class exhibited the highest germination (68%). Small seed size class exhibited the lowest germination percentage and rate in each acorn storage duration. Acorn size also significantly affected seedling emergence and survival in the nursery, and seedling emergence and survival was the lowest in small seed size class (85 and 80%, respectively). Although seedling survival of one-year seedlings in the nursery increased up to large seed size class, maximum survival in nursery conditions was observed in large and medium size classes (89 and 91%, respectively). Thus, acorn size grading in Q. petraea may result in higher germination performance within in a seedbed.

Crecimiento, supervivencia y herbivoría de plántulas de Brosimum alicastrum (Moraceae), una especie del sotobosque neotropical

Growth, survival and herbivory of seedlings in Brosimum alicastrum (Moraceae), a species from the Neotropical undergrowth. Growth responses, survival, and herbivory, on seedlings of Brosimum alicastrum were studied in a neotropical Mexican forest. We selected 122 seedlings and divided them into three groups assigned to defoliation treatments: control or 0 (n=21), 50 (n=51) and 90% (n=50). Every 4 months during two years we measured seedling growth (in terms of relative growth rate in biomass, leaf area growth, produced leaves and height growth) and survival. In addition, we evaluated every 12 months pathogen damage and insect herbivory using a 2 mm-2 grid. Separately, we estimated mammal herbivory in 3-month old seedlings that were selected within a plot of 500 m x 10 m (N=1095). Pathogen damage and insect herbivory were evaluated within the same plot in 113 seedlings. We found that 50 % defoliated seedlings showed compensatory responses in all growth parameters. Relative growth rate and height growth also had a compensatory response in seedlings at 90% defoliation. Relative growth rate and leaf area growth gradually decreased with time although height growth seedling showed an opposite pattern. Leaves produced were not affected by time. Estimated seedling survival probability increased with defoliation to a maximum of 97%, decreasing at 24 month to 37%. Mammal herbivory was more frequent and severe than herbivory caused by pathogens and insects. In some cases, mammal herbivory produced total defoliation. Compensatory growth in leaf area growth, produced leaves and height growth seedling suggest a synergic compensatory mechanism expressed in a whole-plant growth biomass (relative growth rate). Compensation and survival results suggest trade-offs at the leaf level, such as leaf area growth and produced leaves versus chemical defenses, respectively. Rev. Biol. Trop. 56 (4): 2055-2067. Epub 2008 December 12.

Se estudiaron las respuestas de crecimiento, supervivencia y los diferentes tipos de herbivoría sobre plántulas de B. alicastrum en una selva neotropical de México. Se seleccionaron 122 plántulas de una población las cuales se asignaron a tres tratamientos de defoliación: control o 0% (n=21), 50% (n=51) y 90% (n=50). Cada 4 meses durante dos años se midió su crecimiento (en términos de la tasa relativa de crecimiento en biomasa, área foliar, hojas producidas y altura) y supervivencia. Además cada 12 meses, mediante el uso de una cuadricula de 2mm-2, se evaluó la herbivoría causada por patógenos e insectos. También dentro de una parcela de 500 m largo x 10 m de ancho se evaluó en 1095 plántulas de 3 meses de edad la herbivoría por mamíferos. En la misma parcela pero en 113 plántulas se estimó la herbivoría por patógenos e insectos. Las plántulas defoliadas al 50% compensaron su crecimiento en todas las estructuras medidas, pero sólo la tasa relativa de crecimiento y altura lo hicieron con la defoliación al 90%. La tasa relativa de crecimiento y el área foliar disminuyeron gradualmente con el tiempo, contrario a la altura con un patrón opuesto. El número de hojas producidas no se afectó por el tiempo. La probabilidad estimada de supervivencia incrementó hasta un 95% con la defoliación y disminuyó hasta un 37% a los 24 meses. La herbivoría por mamíferos fue el más incidente y severo, en algunos casos hasta un 100% de defoliación. En tanto la causada por patógenos e insectos fue secundaria. El crecimiento compensatorio en área foliar, producción de hojas y altura sugieren un mecanismo compensatorio sinérgico expresado a nivel del crecimiento individual de la planta (tasa de crecimiento en biomasa). Al mismo tiempo junto con la supervivencia sugiere un posible compromiso entre las respuestas de crecimiento a nivel de la hoja - área foliar y hojas producidas - versus producción de defensas químicas.