Conservação de grãos de pólen de mamoneira a baixas temperaturas

Abstract

Conservation of castor bean pollen at low temperaturesThe objective of storing pollen is to preserve material for future use, providing optimal conditions to maintain their original germination, vigor and genetic integrity. The aim of this study was to investigate the germination of castor bean (Ricinus communis L.) pollen after storage at low temperatures. For this purpose, pollen of the cultivars IAC 80 and AL Guarany 2002 were used and stored at four different temperatures, -196; -72; -18; and 4°C, for a period of 60 days. The pollen viability was assessed weekly for five weeks, with a last evaluation performed after eight weeks of storage using the in vitro germination test. Culture medium containing 10 gL -1 agar, 100 gL -1 sucrose, 0.004 g L -1 boric acid, pH 6.0 was prepared and poored into cavity slides, where the pollen was evenly distributed over the surface of the medium. The plates were incubated at 20°C in BOD. The experiment was arranged in a 2x4 factorial completely randomized design (2 cultivars x 4 temperatures) for each storage time, with 100 pollen grains analyzed per repetition, totaling six of each treatment. There was significant difference between treatments for the cultivar x temperature interaction in the fifth week of observation (p<0.05). Other cultivar x temperature interactions were highly significant at all times of observation (p<0.01). It is therefore concluded that the use of ultra low temperatures allows the maintenance of castor bean pollen viability until the fifth week of storage.

<b>Morphology and viability of castor bean genotypes pollen grains

“…Different culture media have been used to germinate the pollen grains of a large number of species in vitro (Chagas et al, 2010;Cuchiara et al, 2012;Soares et al, 2008;. Several authors have used carbohydrates and germinationstimulating substances (nutrients and hormones) in culture medium.…”

“…The viability of pollen grains can be determined by direct methods such as the induction of in vitro (Dane & Ekici, 2011;Cuchiara, Silva, & Brobowski, 2012;Imani, Kazem, Saeed, & Seiyed, 2011;Machado et al, 2014) and in vivo (Dane & Ekici, 2011;Fakhim, Hajilou, & Zaare, 2011) germination or indirect methods based on cytological parameters such as staining (Ćalić, Devrnja, Kostić, & Kostić, 2013;Munhoz, Luz, Meissner Filho, Barth, & Reinert, 2008).…”

“…This technique has been widely studied in several species (Cuchiara et al, 2012;Machado et al, 2014), including oleaginous species such as the castor bean, cotton, soy, canola (rapeseed), oil palm, sunflower, babassu palm and peanuts. Each species requires a specific protocol and culture medium to obtain good germination.…”

Determination of cardinal temperatures for sugar apple ( Annona squamosa L.)

“…High temperatures between 20 °C and 30 °C are more important for germination and elongation of the pollen grain tubes of custard apples compared to lower temperatures, but germination and growth are affected above 30 °C, with higher temperatures being detrimental (Figures 2 and 3). This can be explained because at low temperatures, enzymatic reactions slow down due to a drop in kinetic energy, reducing the cellular metabolism of pollen grains (Cuchiara et al, 2012). Increasing the temperature can accelerate the rate of a reaction up to a certain limit, but after this limit is reached, complete enzyme denaturation occurs (Taiz and Zeiger, 2013).…”

Genetic parameters of pollen viability in guava (Psidium guajava L.)

“…Knowledge about pollen viability is important for taxonomy, ecology and palynology, providing information on the reproductive biology and conservation of the species (Alexander, 1980;Souza et al, 2002;Usman et al, 2013). It is also critical in genetic breeding, in the routine use of artificial pollination (Nascimento et al, 2003;Munhoz et al, 2008); in pollen monitoring during storage; in evaluation of pollen germination after exposure to stresses; in analyses of dispersion and gene flow; and in studies of genetics and pollen-stigma interactions, incompatibility and fertility (Santos et al, 2007;Bauermann et al, 2009;Almeida et al, 2011;Soares et al, 2011;Cuchiara et al, 2012 ).…”