Effects of brassinosteroids and gibberellin on water uptake and performance of soya bean seeds under different temperatures

Low temperature has negative effects on seed performance and seedling growth in soya bean, reducing stand establishment. It was hypothesised, that seed treatment with plant hormones could improve seed imbibition and performance at low temperature. Therefore, the effects of 24-epibrassinolide (EBL) and gibberellic acid (GA3) on soya bean seed germination were studied. Seeds of 'CM60' and 'CM0701-24' were imbibed with 0.25 or 0.50 ppm EBL, 50 or 100 ppm GA3, or distilled water at 10, 15, 20 and 25°C. The seed imbibition patterns of the two soya bean varieties followed a similar trend. Low temperature delayed seed imbibition resulting in longer time to reach the end of phases 1 and 2 of seed germination as compared with high temperature. Soya bean seeds treated with 50 or 100 ppm GA3 showed increased germination index, shoot and root length and reduced mean germination time. Thus, 50-100 ppm GA3 could be used as a pre-soaking seed treatment to improve soya bean seed and seedling performance under low temperature.

GERMINATIVE PERFORMANCE OF MULUNGÚ SEEDS (Ormosia grossa Rudd) AFTER DORMANCY OVERCOMING

ABSTRACT Ormosia grossa Rudd is an Amazonian species that presents bicolor seeds, allowing its exploration for handicraft and decoration making. This paper aimed to analyze the influence of different methods to overcome dormancy on the germinative performance of Ormosia grossa seeds. To conduct the experiment, the following treatments were established: T1= scarification with 80-grit sandpaper and water immersion at room temperature for 24 hours; T2= puncturing and water immersion at room temperature for 24 hours; T3= scarification with 80-grit sandpaper; T4= puncturing; T5= immersion in water heated to 80 ºC for five minutes, and T6= Control - seeds without any treatment. The seeds germinate slowly and irregularly. Depending on the treatment, germination started between 10 and 32 days and, if there is no adequate pre-germinative treatment to overcome dormancy, it can exceed such time. The phytomass performance and seedling lengths were superior in the T1 and T2 treatments. The scarification by abrasiveness and puncturing treatments are efficient to overcome dormancy, thus increasing the speed (3.76 and 3.12) and germination percentage (98% and 96%) after ten days. The control was 0.01 (IVG), and germination of 37%. Therefore, it is recommended the method of scarification with sandpaper followed by seed imbibition in water at room temperature for 24 hours, as it provides the best seedling performance and germination.

Tratamientos pregerminativos para semillas de Prunus cercocarpifolia Villarreal (Rosales, Rosaceae), especie endémica de la Sierra Zapalinamé, Coahuila, México

Prunus cercocarpifolia Villarreal (Rosaceae) is an endemic shrub species restricted to the Sierra Zapalinamé in southeastern Coahuila, Mexico. It is a refuge and food source for native fauna, but their populations have been affected by human activities. In this study, we evaluated 11 pregerminative treatments in seeds of this species. These treatments consisted of the imbibition in water and stratification at different times and temperatures. The treated seeds were sown, and we assessed the percentage of germinated, dark, and non-germinated seeds, as well as the pro- portion of normal and abnormal seedlings. The seed imbibition with endocarp for 48 h at 30°C reached the highest germination percentage (89%), with all seeds being germinated, and 58% of normal seedlings produced. With the stratification for 8 days at 5°C, all seeds were germinated and a 64% of normal seedlings was achieved. Implementing these treatments on nursery production can contribute to the conservation of this endemic species of northeastern Mexico

In Vitro Germination and Initial Seedling Development of Krantz Aloe by Smoke-saturated Water and Seed Imbibition

Krantz aloe (Aloe arborescens) is one of two aloe species currently used for the extraction of active ingredients that can be useful in the cosmetic and pharmaceutical industries. However, krantz aloe plants have been frequently collected from the wild, which is threatening wild populations. In vitro tissue culture would allow the growth of krantz aloe under controlled conditions, optimizing the production of active ingredients without risk to wild populations. The establishment of cultures from krantz aloe plant explants has proved difficult as a result of the long response times of the explants and their release of polyphenols. Krantz aloe seeds are not commonly used as a means of propagation because of their low germination percentages. The objective of this study was to evaluate the effects of seed imbibition (SI) with water and the addition of smoke-saturated water (SSW) to the culture medium on the in vitro germination and initial seedling development of krantz aloe. Seeds were germinated in vitro in axenic conditions. The treatments used were the addition of 10% SSW to the culture media, SI, and a combination of both (10% SSW + SI). Daily germination was recorded and gross morphology was measured after 1 month of culture establishment. The maximum germination percentage (GP) was achieved when 10% SSW was in the medium (97.2%), followed by the combined application of 10% SSW + SI (96.6%), both of which were almost 30% greater and significantly different from that of the control (69.4%). SI had an 83.3% GP. No significant differences were observed among treatments in any of the observed development parameters (leaf and root length and number). Taken together, these findings show that the use of SSW improves the in vitro germination of krantz aloe without affecting seedling development, indicating preliminarily that SSW represents a useful in vitro germination promoter for this species.

Evaluation of pre-germination treatments on four native species of the High Andean forest

High Andean forests are strategic ecosystems with high diversity of native and endemic plants; however, these natural ecosystems are affected by agricultural expansion. Knowledge on the propagation of native plants is essential to restore these environments. This research aimed to evaluate germination in the following native species: Viburnum triphyllum Kunt. (Caprifoliaceae), Oreopanax floribundum Kunth, (Araliaceae), Weinmannia tomentosa L.f. (Cunoniaceae), and Tournefortia fuliginosa Benth. (Boraginaceae) in Botana experimental farm of Universidad de Nariño. This study was conducted between October (2016) and February (2017). For each species, an unrestricted randomized split-plot design was established. The main plot included the substrates (S), and the sub-plots included the different pre-germination treatments (PM) with three repetitions. The results showed statistically differences in germination percentage among pre-germination treatments for O. floribundum. The highest germination percentage (42%) for this species was achieved with seed imbibition for 48 hours at 22°C. Moreover, W. tomentosa showed statistical differences for S and PM, with a germination percentage of 74% with imbibition for 48 h at 22°C and sand substrate. T. fuliginosa did not show relevant differences; however, it had a germination percentage of 47%. V. triphyllum did not germinate; therefore, further evaluations of pre-germination treatments should be required.