Abstract
Abstract: Buchenavia tomentosa produces fruits with ecological function for Cerrado’s fauna. The aims of this paper were to quantify seed germination and behavior on thermal conditions and explain about water absorption of dispersal structure in B. tomentosa seeds. Ripe fruits were pulped, the endocarp removed, and seeds used in the germination tests at temperatures of 10 to 45 °C. Seeds were placed in rolls of filter paper and then placed in germination chambers, at twelve hours of photoperiod. Germination models at sub and supra optimal temperatures were made from the germination rate (Tg), from the time to germination of 50% of the seeds (t50). Germination speed index (GSI), measurements of shoot and root lengths and dry mass at each temperature were obtained. The water imbibition curve of seed with or without endocarp adhered and scarified or not was made and other samples were tested for emergence in sand. Cardinal temperatures were: base temperature (Tb) of 9.23 °C; maximum temperature (Tmax) of 44.6 °C; optimum temperature (To) of 29.24 °C and thermal time of 89.71 °C.days. Seedlings showed higher GSI, root and aerial part length and higher root dry mass at the optimal temperature. The endocarp retards, but does not prevent water absorption and emergence.
Highlights
Germination occurs at a minimum cardinal temperature range (Tb), below which the germination process does not occur; a maximum temperature (Tmax), above which the germination is not complete; and, an optimum temperature (To), in which the germination speed is faster
Dynamics of cumulative germination by the time of B. tomentosa seeds without endocarp adhered varied at different temperatures
The t50 was slower at 15 and 40 °C; at 20 or 35 °C the seed behavior was similar (Figure 2). These results show that changes in temperatures below 25 °C and above 30 °C become effective in reducing the germination time of 50% of B. tomentosa seeds, and this reduction is quantitatively similar at both sub and supra optimal temperatures
Summary
Germination occurs at a minimum cardinal temperature range (Tb), below which the germination process does not occur; a maximum temperature (Tmax), above which the germination is not complete; and, an optimum temperature (To), in which the germination speed is faster. Cardinal temperatures serve as basis of predictive models, due to the frequently linear relationship found between germination rate (Tg) and temperature, in sub and supra-optimal models (Bradford, 2002). Some thermal studies based on germinations models were carried with seeds of tropical forest (Mattana et al, 2018; Lamarca et al, 2011; Cardoso and Pereira, 2009). These studies can be useful to understand ecological aspects related to seed germination, such as the basis and optimal temperature for seed germination and vigor. These factors can support models for the seedlings’ establishment in some areas, as well as resilience of plant communities on habitat
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