In vitro propagation of the neotropical giant bamboo, Guadua angustifolia Kunth, through axillary shoot proliferation

Guadua angustifolia Kunth was successfully propagated in vitro from axillary buds. Culture initiation, bud sprouting, shoot and plant multiplication, rooting and acclimatization, were evaluated. Best results were obtained using explants from greenhouse-cultivated plants, following a disinfection procedure that comprised the sequential use of an alkaline detergent, a mixture of the fungicide Benomyl and the bactericide Agri-mycin, followed by immersion in sodium hypochlorite (1.5% w/v) for 10 min, and culturing on Murashige and Skoog medium containing 2 ml l−1 of Plant Preservative Mixture®. Highest bud sprouting in original explants was observed when 3 mg l−1 N6-benzylaminopurine (BAP) was incorporated into the culture medium. Production of lateral shoots in in vitro growing plants increased with BAP concentration in culture medium, up to 5 mg l−1, the highest concentration assessed. After six subcultures, clumps of 8–12 axes were obtained, and their division in groups of 3–5 axes allowed multiplication of the plants. Rooting occurred in vitro spontaneously in 100% of the explants that produced lateral shoots. Successful acclimatization of well-rooted clumps of 5–6 axes was achieved in the greenhouse under mist watering in a mixture of soil, sand and rice hulls (1:1:1).UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro para Investigaciones en Granos y Semillas (CIGRAS)UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Zootecni

Micrografting of Protea cynaroides

The inability to induce rooting of in vitro-established Protea cynaroides microshoots has prevented the production of complete plantlets. A successful shoot-tip micrografting technique was developed using in vitro-germinated P. cynaroides seedlings as rootstocks and axenic microshoots established from pot plants as microscions. Thirty-day old seedlings, germinated on growth-regulator-free, half-strength Murashige and Skoog medium, were decapitated and a vertical incision made from the top end. The bottom ends of microshoots established on modified Murashige and Skoog medium were cut into a wedge (‘V’) shape, and placed into the incision. The micrografted explants were cultured in a growth chamber with the temperature adjusted to 25 ± 2°C, with a 12-h photoperiod. Best results were obtained by placing the microscions directly onto the rootstock without any pre-treatments. Dipping the explants in anti-oxidant solution or placing a layer of medium around the graft area led to the blackening of the microscion. Abbreviations EDTA Ethylenediaminetetraacetate - BAP 6-Benzylaminopurine - GA3 Gibberellic acid - PAR Photosynthetic active radiatio

Flowering cycles of woody bamboos native to southern South America

Neotropical woody bamboos range from northern Mexico to southern Argentina and Chile. The most interesting aspect of bamboo biology is their flowering habit. The species that are the most intriguing are those that manifest a cyclic pattern of gregarious flowering after long vegetative periods. The flowering cycle has been described in very few species. The goal was to identify mass flowering events of woody bamboo species native to Argentina and neighboring areas, and to estimate the flowering cycle of each species. Sixteen species were surveyed: Chusquea culeou, C. deficiens, C. lorentziana, C. montana, C. quila, C. ramosissima, C. tenella, C. valdiviensis; Colanthelia rhizantha; Guadua chacoensis, G. paraguayana, G. trinii; Merostachys clausenii, M. multiramea, Rhipidocladum neumannii and R. racemiflorum. To reconstruct flowering dates, information from literature and herbarium collections was consulted and more than 990 records were gathered. Flowering cycles were estimated by recording the intervals between reported flowering events. Evidence of regular flowering cycles of ca. 30 years was found for most of the species considered. There is a remarkable concentration of flowering cycles about multiples of 15–16 years. Flowering synchrony among different species of woody bamboos was recorded for the first time in South America.Fil: Guerreiro, Carolina Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentin