Desiccation tolerance in seeds of Annona emarginata (Schldtl.) H. Rainer and action of plant growth regulators on germination

Abstract

Annona emarginata (Schldtl.) H. Rainer ("araticum-de-terra-fria") is used as a rootstock for several species of Annonaceae. It is suggested that these seeds should be sown immediately after extraction and, therefore, they could be intolerant to desiccation. There are several mechanisms involved with desiccation tolerance. Soluble sugars, for example, can accumulate and act as osmoprotectants for the membrane system during desiccation. The aim of this study is to assess desiccation tolerance in A. emarginata seeds. In addition, we examined the soluble sugars involved in desiccation tolerance. Finally, we determined the effect of gibberellic acid (GA 4+7 ) and N-(phenylmethyl)-aminopurine in promoting the germination of seeds with different water contents. The experiment consisted of a randomized 4x5 factorial design (desiccation levels x concentration of growth regulators). After drying, seeds containing 31 (control), 19, 12 and 5% water were incubated in different concentrations of GA 4+7 N-(phenylmethyl)-aminopurine (0, 250, 500, 750 and 1000 mg L -1 ) for 60 hours. The experiment was conducted in a germination chamber with alternating temperature and photoperiod of 20ºC for 18 hours of darkness and 30ºC for 6 hours of light. We analyzed electrical conductivity, germination rate, mean germination time, germination speed, frequency and uniformity of germination, percentage of dormant seeds and soluble sugar profile in intact seeds through high-performance liquid chromatography (HPLC). The data were subjected to analysis of variance, and the means were compared using Tukey's test at a threshold of p<0.05. The results showed that seeds of A. emarginata appears to be desiccation tolerant and, also, that sucrose increases when seed water content is reduced to values as low as 12%, exogenous GA 4+7 +N-(phenylmethyl)-aminopurine improves its germinability.

Soluble sugars and germination of Annona emarginata (Schltdl.) H. Rainer seeds submitted to immersion in GA3 up to different water contents

“…In Annona emarginata (Schltdl.) H. Rainer seeds, Costa et al (2011) and Corsato et al (2012) used the immersion for 60 hours (based on transition from Phase I to Phase II) in GA 4+7 + N-(phenylmethyl)-aminopurine, obtaining 27% and 70% germination, respectively.…”

Water uptake by Annona diversifolia Saff. and A. purpurea Moc. & sessé ex dunal seeds (Annonaceae)

“…Some studies to overcome seed dormancy with the application of plant growth regulators are been done in Annonaceae (SMET et al, 1999;FERREIRA et al, 2002;LIMA-BRITO et al, 2006;SILVA et al, 2007;BRAGA et al, 2010;OLIVEIRA et al, 2010;COSTA et al, 2011;CORSATO et al, 2012) and in this cases are necessary to determine the time of immersion treatments in the solutions, which is made from the elaboration of the acquisition water curve. Furthermore, obstructions on purchase of water by seeds are also detected with the completion of this curve, as well as times of osmotic conditioning (VARIER et al, 2010).…”

OVERCOMING SEED DORMANCY IN Annona macroprophyllata AND Annona purpureaUSING PLANT GROWTH REGULATORS

“…The seeds were then placed on filter paper for seven days on top of a laboratory bench (25 °C +/-2 ºC) for surface drying. The initial moisture content of the seeds (10%) was determined using the oven-drying method at 105 ºC for 24 h, with four replicates of 25 seeds each (CORSATO et al, 2012). Additionally, seed viability was evaluated using the tetrazolium test with four replicates of 25 seeds each.…”

“…This period was established considering the water uptake curve previously performed (FERREIRA et al, 2014). After treatments, seeds were placed in a roll of paper moistened with distilled water (2.5 times its weight) (CORSATO et al, 2012). Seeds were kept in a germinator at 30 °C (±2 °C) average temperature at which the seeds are exposed in their habitat with a relative humidity ranging from 50 to 60% and in the absence of light (GONZALEZ-ESQUINCA et al, 2015) Observations were made every two days…”

“…The following variables were calculated: percentages of germination (%G), dormant seeds (%DS) and dead seeds (%DS); relative frequency (f) according to CORSATO et al (2012); germination rate index (GRI) according to Maguire (1962); and mean germination time (MGT) according to Edmond and Drapala (1958), cited by Ranal and Santana (2006). The GRI and MGT values were obtained using the following equations: The data were subjected to an analysis of variance, and the means were compared using Tukey's test at a 5% probability between regulators.…”