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The major problem in seedlings production of jasmin box (Phillyrea latifolia) is the poor and irregular germination due to seed dormancy. The objective of the present study was to evaluate methods of seed pre-treatments to increase germination. The effect of different solutions of KOH and NaOH, wood ash lye, GA3 and cold or warm stratification on germination were evaluated. Sets of four replicates of 25 seeds were soaked for 24 hours in KOH and NaOH solutions of 0.2, 0.5, 1 and 2 %, in wood ash lye solutions of 33, 66, 133, 166, 532 g L-1 and in GA3 solutions of 250, 500, 1000, 2,000, 3,000 mg L-1. A control set of seeds was imbibed in water for 48 hours. All sets went through zero, two, four and six months of cold (2-4 °C) or warm (15 °C) stratification. The seeds were incubated in petri dishes filled with moistened sand, at two alternating temperatures (20/15 and 30/20 °C) with a light period of 16 hours. From the results we conclude that: Chemical pre-treatments with KOH and ash lye and warm stratification increased germination to 96 %. Treatment with water and warm stratification also increased germination to 79 %. Treatment with 250 mg L-1 GA3 and six months warm stratification increased germination to 70 % while higher concentrations had a negative effect. Cold stratification did not break dormancy. Optimum germination temperature in a growth chamber was 15-20 °C, while temperature at 20-30 °C inhibited germination., Un problema en la producción de plantas de labiérnago (Phillyrea latifolia) es la irregular y baja germinación debido al letargo de las semillas. El objetivo del presente estudio fue evaluar tratamientos previos a las semillas para aumentar su capacidad germinativa. Se evaluó el efecto de soluciones de KOH y NaOH (0,2, 0,5, 1 y 2 %), lejía de ceniza de madera (33, 66, 133, 166, 532 g L-1) y GA3 (250, 500, 1.000, 2.000, 3.000 mg L-1) y estratificación en frío o en caliente. Conjuntos de cuatro repeticiones de 25 semillas se sumergieron durante 24 horas en las soluciones. Adicionalmente, se aplicó un tratamiento control conjunto de semillas embebidas 48 horas en agua. Todos los conjuntos pasaron por 0, 2, 4 y 6 meses de estratificación en frío (2-4 °C) o temperatura ambiente (15 °C). Las semillas, en placas de Petri con arena húmeda, se incubaron a dos temperaturas alternantes (20/15 y 30/20 °C) con un periodo de luz de 16 horas. Se concluyó que: los tratamientos con KOH y lejía de ceniza de madera y la estratificación cálida aumentaron significativamente la germinación hasta el 96 %. Tratamientos con agua y estratificación caliente también aumentaron la germinación a 79 %. El tratamiento con 250 mg L-1 GA3 y seis meses estratificación cálida aumentó la germinación hasta el 70 %, pero las concentraciones más altas tuvieron efecto negativo. La temperatura de germinación en la incubadora fue 15-20 °C. La alta temperatura de incubación (20-30 °C) y la estratificación fría (2-4 °C) resultaron en nula germinación.

Physical dormancy ofRobinia pseudoacaciaseeds makes it a challenge for scientists and forest managers to obtain a homogeneous germination for larger seed samples. Water imbibition of the seeds can be achieved through manual piercing of the seed coat, but this method remains time consuming and heterogeneous. We tested several ecologically friendly methods to break seed dormancy, including manual pin puncture, water soaking, oven dry-heating (two temperatures) and sanding. Sanding was performed using an automatic grinder to control shaking duration (three durations) and get a homogeneous scraping of the coat. All methods, except dry-heating, resulted in successful dormancy breaking; water soaking was the least efficient method, attaining 57% germination. Sanding proved to be as efficient as puncturing (97%) but long duration sanding (10 or 15 min) could damage cotyledons, which would impede further development of the plant. Short-time sanding (5 min) proved to be the best method to reach high total germination and healthy (undamaged cotyledon) seedlings, and was successfully applied to 500 seeds. The reference puncture method and the automatic sanding were also tested on seeds of nine Fabaceae species and proved to be efficient for some species. Automated sanding can thus be used as a standard to break physical dormancy of black locust or other Fabaceae seeds to allow further comparative studies of plant populations or genotypes.

Protein synthesis in cotyledons and embryo axes of Norway maple (Acer platanoides L.) was studied in seeds stratified at 3 or 15oC. At 3oC stratification, germination of seeds starts after 9 weeks, at 15oC stratification germination does not occur. The changes of protein synthesis level in both temperatures had two phasic character. In embryo axes (3 and 15oC) protein synthesis grow up, but in cotyledons (3oC) synthesis of proteins decrease. Generally, activity of protein synthesis was higher at 3oC, as like as DNA level was higher. After imbibition, in cold and warm stratification, in embryo axes, many new protein are become visible. We expect, that two from this proteins, determined as A and B my be connected with the releasing from dormancy. In seeds stratified at 15oC, these proteins are occuring in vestigal amount or are completely absent.

Camellia japonica L. is an evergreen shrub whose cultivars are of great ornamental value. In autumn, after flower bud differentiation, dormancy is initiated. As in many other spring flowering woody ornamentals, winter low temperatures promote dormancy release of both flower and vegetative buds. However, warm spells during late autumn and winter can lead to unfulfilled chilling requirements leading to erratic and delayed flowering. We hypothesized that storing plants at no light and low temperature could favor dormancy breaking and lead to early and synchronized flowering in response to forcing conditions in C. japonica ‘Nuccio’s Pearl’. Plants with fully developed floral primordia were stored at dark, 7°C, and RH > 90% for up to 8 weeks. To monitor endodormancy release during the storage, we evaluated the content of abscisic acid (ABA) in flower buds and the expression profiles of five putative genes related to dormancy and cold acclimation metabolism in leaves and flower buds. In addition, the expression of four anthocyanin biosynthesis pathway genes was profiled in flower buds to assess the effect of the treatment on flower pigment biosynthesis. At 0, 4, 6, and 8 weeks of cold treatment, 10 plants were transferred to the greenhouse and forced to flower. Forced plant flower qualities and growth were observed. The ABA content and the expression profiles of two dormancy-related genes (CjARP and CjDEH) suggested that dormancy breaking occurred after 6–8 weeks of cold treatment. Overall, plants treated for 6–8 weeks showed earlier vegetative sprouting, enhanced, and homogeneous flowering with reduced forcing time. Prolonged cold treatments also reduced flower size and longevity, anthocyanin content, and pigment biosynthesis-related gene transcripts. In conclusion, the cold treatment had a promotive effect on dormancy breaking but caused severe drawbacks on flower quality.

Este trabalho foi realizado no ano de 1999, na Estação Experimental Agronômica da Universidade Federal do Rio Grande do Sul, localizada no município de Eldorado do Sul, Estado do Rio Grande do Sul, latitude 30°05'52" S, longitude 51°39'08" W e altitude de 46 metros. Foram testados os efeitos da Cianamida Hidrogenada (C.H.) e Óleo Mineral (O.M.) em mistura, Óleo Mineral (O.M.) e Thidiazuron (TDZ) com Óleo Mineral (O.M.), sobre brotação, frutificação, produção e antecipação de colheita. Os tratamentos foram aplicados quando as plantas estavam no estádio fenológico A. Foram testados os seguintes tratamentos: C.H. 0,5%, 1,0% e 1,5% + O.M 1,0%, O.M. 1,0% e 2,0%, TDZ 200 e 400 ppm + O.M. 2,0% e testemunha (sem pulverização). Os tratamentos não anteciparam a brotação das gemas vegetativas. O tratamento C.H. 1,5% com O.M. 1,0% proporcionou produção suficiente para viabilizar o cultivo do "Chiripá" em condições de inverno ameno, mas não houve diferenças significativas no peso médio dos frutos. O TDZ, nas dosagens testadas, não se mostrou eficiente na quebra de dormência desta cultivar. Não houve efeito na antecipação da colheita. The present work was conducted in 1999, at the Estação Experimental Agronômica of the Universidade Federal do Rio Grande do Sul, located in the county of Eldorado do Sul, Rio Grande do Sul, latitude 30º05'52"S, longitude 51º39'08" W and altitude at 46 meters. Were tested the effects of the Hydrogen Cyanamide (H.C.) and Mineral Oil (M.O.) in mixture, Mineral Oil (M.O.) and Thidiazuron (TDZ) with Mineral Oil (M.O.), on bud break, yield and anticipation of the crop. Trees were spayde at bud stage A. The following treatments were tested: H.C. 0,5%, 1,0% and 1,5% + M.O. 1,0%, M.O. 1,0% and 2,0%, TDZ 200 and 400 ppm + M.O. 2,0% and control (without any spray). The treatments did not result in anticipation of the bud burst. The treatment H.C. 1,5% and M.O. 1,0% provided enough yield to make possible the cultivation of "Chiripá" in mild winters conditions, but there was not significant difference in fruit weight. TDZ, at the tested concentrations, was not efficient to break the dormancy of this cultivar. No effect or crop anticipation was observed.

Con objeto de buscar información para un mejor control de Oxalis latifolia Kunth, se ha estudiado el efecto que presentan la temperatura y la humedad sobre la activación de sus bulbos, tanto en la forma común como en la forma Cornwall de la misma. Los bulbos de la mala hierba se mantuvieron en un refrigerador a +4°C durante 13, 20, 27, 41, 48 y 55 días. Se sacaron tres grupos de 30 bulbos de cada forma en cada fecha de muestreo y se colocaron a 21°C; 15 de ellos se mantuvieron en condiciones de sequía —no se regaron— y otros 15 en condiciones de humedad —añadiendo el agua necesaria—. Los resultados muestran que la activación ocurre durante un período prolongado de tiempo en ambas formas, tanto en seco como en húmedo. También se observó que los bulbos secos se activaron antes que los húmedos y los de la forma común antes que los Cornwall. Se observaron dos patrones de activación: los bulbos secos de la forma común generalmente presentaron una activación que sigue un patrón logarítmico, mientras que sus bulbos humedecidos mostraron una tendencia linear; los bulbos Cornwall se activaron con una tendencia exponencial en la mayoría de los casos. El tiempo medio requerido para la activación después del almacenamiento en frío fue constante en la forma común, sin embargo la activación de Cornwall fue más rápida cuanto más tiempo permanecieron almacenados en frío. The effect of temperature and moisture on the activation of two forms of Oxalis latifolia Kunth bulbs —common and Cornwall— was studied. Gaining knowledge about the conditions needed for their activation may contribute to the control of this weed. Bulbs were kept in a refrigerator at +4°C for 13, 20, 27, 41, 48 and 55 days. At each sampling date, three sets of 30 bulbs of both forms were transferred from 4°C to 21°C; 15 were kept under dry conditions and 15 under wet conditions. For both forms, and under both wet and dry conditions, activation occurred over a prolonged period of time. Dry bulbs were activated earlier than the wet bulbs, and the common form was activated earlier than the Cornwall form. Two different patterns of activation behavior were observed: dry bulbs of the common form usually followed a logarithmic activation pattern, while those subjected to the wet treatment were activated in a linear fashion. Bulbs of the Cornwall form were activated exponentially in the majority of cases. The mean time required for activation after cold storage was constant in the common form, while in the Cornwall form, activation was faster the longer the period of cold storage the bulbs had been previously subject to.

Models concerning the effects of temperature on dormancy release in woody plants were tested using two-year old seedlings of Scots pine ( L.) and Norway spruce ( (L.) H. Karst.). Chilling experiments suggest that the rest period has a distinct end point. Before the attainment of this end point high temperatures do not promote bud development towards dormancy release, and after it further chilling does not affect the subsequent bud development. A new hypothesis of dormancy release is suggested on the basis of a comparison between present and earlier findings. No difference in the proportion of growth commencing seedlings were detected between the forcing temperatures of 17°C and 22°C. The rest break of 50% of Norway spruce and Scots pine seedlings required six and eight weeks of chilling, respectively. Great variation in the chilling requirement was found, especially for Scots pine.Pinus sylvestrisPicea abies

Logical structure of three simulation models and one conceptual model concerning effects of temperature on dormancy release in woody plants was examined. The three basic types of simulation models differed in their underlying assumptions. Contrasting implications of the models were inferred by deduction. With the aid of these implications, the model types can be tested using experiments with continuous and interrupted chilling. Similarly, implications of the conceptual model of rest phases were inferred, by which the model can be tested using experiments with continuous chilling and forcing in multiple temperatures. The possibilities to synthetize the conceptual model with any of the three simulation model types, as well as the biological interpretation of the model variables, were discussed. The PDF includes an abstract in Finnish.

The occurrence of on clear-cut and burned forest soil and its disappearance in 4â6 years after disturbance is attributed to its germination ecology. Initially the seeds are dormant 96â100% and remain dormant in nylon gaze bags in different types of forest humus layers at least 10 years. Dormancy is released in laboratory (1) by treatment of 100 ppm aqueous solution of GA, (2) by heating the dormant seeds to 40â55°C for 1â5 h, and (3) by 1% KNO solution. It is concluded that conditions in clear-cut and burned areas favour germination of seeds in regard to temperature and content of nitrates in contrast to humus of closed vegetation where the seeds remain dormant.Caleopsis bifida33