ISHS II International Symposium on Edible Alliaceae REMOVAL OF N, P, K AND CA BY AN ONION CROP (Allium cepa L.) IN A SILTY-CLAY SOIL, IN A SEMIARID REGION OF VENEZUELA

Aim of study: The objective of this study was to present statistical information pertaining to recurrent inconsistencies found in the literature of the last 25 years that involve calculation of the GR and the errors that this may entail when interpreting the seed vigor of different botanical materials.Materiales y métodos: After filtering articles that did not present numerical results or in which the application of Maguire's formula was not clearly indicated, a total of 124 papers were ultimately used in this study.Main results: Germination rate (GR) represents the potential of seeds to germinate and, along with germination percentage (GP), are the two most important measurements when evaluating seed quality. The correct calculation of GR allows the seeds classification according to their vigor and capacity to produce healthy seedlings, so it is very important to rely on the adequate mathematical formula for this purpose. According to the formula developed by Maguire, this parameter is calculated by the sum of values obtained when dividing the GP at different times (i.e. daily) by the total time elapsed since the start of the test. We have found from the relevant literature that different authors have been using different ways of applying the formula, which makes it difficult to directly compare the results.Research highlights: A total of 54.8 % of the papers reviewed, belonging mainly to the theme of forestry, presented objectionable application of the formula. Publication of this warning may help to reduce the occurrence of this situation in the future.Keywords. Germination percentage, germination speed, Maguire’s formula, seed vigor.

Background Ormosia macrocalyx is a tropical forest tree classified as endangered. Its seeds experience problems of dispersion and apparent physical dormancy due to their hard seed coating. Hypotheses 1) The stages of dehiscence of the fruits of Ormosia macrocalyx influence the germinative behavior of its seeds. 2) Pregerminative treatments will improve the germination process of the seeds stored under refrigeration. Study species Ormosia macrocalyx Ducker. Study site and period Villahermosa, Tabasco, Mexico from October 2012 to October 2014. Methods Two completely randomized experiments were conducted in order to analyze the germination process by 1) evaluating germination in seeds from fruit at three stages of dehiscence (closed, semi-open, and open fruit) and 2) applying four treatments, including three pregerminative treatments (water soaking for 24 h, mechanical scarification and scarification+1 % gibberellic acid) plus an untreated control, to seeds stored under refrigeration for 17 months. Results Differences were found in germination rate (GR), corrected germination rate (CGR) and time to attain 50 % germination (T50) among treatments in the first experiment, with the seeds from open fruits presenting the lowest response (3.31 % day-1 for GR and CGR, and 15.8 days for T50), although all treatments showed similar times for the initiation of germination (GI) and final germination percentage (GP). In the second experiment, the effect of scarification was greater than both the control and soaking treatments. Scarification treatment values were 68.0 % (GP), 12.0 days (GI), 4.53 % day-1 (GR), 6.65 (CGR) and 14.5 days (T50). Addition of gibberellic acid did not produce any further advantage over scarification alone. Conclusions Seeds from open fruits have lower germination rates, although the final GP is not affected. Stored seeds present physical dormancy but lose viability with storage and, when collected after remaining attached to the tree for undefined periods, scarification can greatly improve their germination rate.

Annona reticulata es una especie nativa del Neotrópico, poco domesticada, común en huertos familiares y su fruto es de sabor agradable. Como una estrategia de conservación del germoplasma, y considerando que determinados tratamientos pregerminativos pueden favorecer su capacidad de germinación, se plantearon dos objetivos: la caracterización morfológica de frutos y semillas, y el estudio de la respuesta a varios tratamientos pregerminativos. Las muestras provienen de Tabasco, México. Se midieron frutos y semillas. Las semillas se sometieron a seis tratamientos pregerminativos: Testigo (T1), escarificación mecánica (T2), remojo en ácido giberélico (AG3 100 mg L-1 por 3 h) (T3), remojo en AG3 (100 mg L-1 por 6 h) (T4), remojo en AG3 a 200 mg L-1 por 3 h (T5), y escarificación mecánica + remojo en AG3 (100 mg L-1 por 24 h) (T6). Se determinó el porcentaje total de germinación (PG) y la tasa de germinación (TG) en un ensayo completamente al azar con cinco repeticiones. El peso promedio del fruto fue de 422,2 g, con 113,8 semillas, de los cuales el 69,22 % estuvo representado por el peso de la pulpa. La germinación criptocotilar epígea inició el día 17 y alcanzó su máximo (76,6 %) el día 31. La escarificación mecánica (T2) promovió los mayores valores de PG y TG, mientras que el uso del AG3 afectó la germinación y produjo los menores valores a medida que se incrementaron las concentraciones y tiempos de remojo del producto.

ISHS International Symposium on Irrigation of Horticultural Crops THE INFLUENCE OF SOIL MOISTURE ON THE VEGETATIVE AND REPRODUCTIVE GROWTH OF ORANGE TREES UNDER TROPICAL CONDITIONS

Annona reticulata is an important native American species recognized since pre-Columbian times. Although rarely cultivated, it has become a major source of natural medicine, among other applications of global importance. To obtain general and up-to-date information on the different aspects of this species, a comprehensive bibliographic review was conducted using digital sources such as Web of Science and Google Scholar, as well as reviews in physical and virtual herbaria to obtain georeferenced data and determine their current and potential eco-geographic distribution (Global Biodiversity Information Facility, Universidad Juárez Autónoma de Tabasco, Herbario Nacional de México, and Instituto de Ecología). The morphological varieties were identified and characterized through fruit collections in the Sierra Subregion, in Tabasco, Mexico. The literature review focused on the botanical description, anatomy, physiology, propagation, and associated diseases and pests of the plant, as well as its economic importance. High-level information was recorded regarding phytochemical aspects and application in medicine outside Mexico. It was determined that there is little specific data on the plant's anatomy, physiology, and post-harvest physiological factors. Moreover, in some topics, the existing information is obsolete: this is the case for themes of agronomic and phytosanitary management, as well as studies of phylogenetics and molecular markers for conservation and breeding. Its status as a native species suggests a need for conservation. However, for preservation in germplasm banks, it is essential to determine the plant tolerance to desiccation and low temperatures.