Fruit and seed biometry and germination of Dimorphandra mollis Benth. and Dimorphandra wilsonii Rizz. (Fabaceae-Caesalpinioideae) seed

Dimorphandra mollis is a commonly occurring tree species of the Cerrado. D. wilsonii, which is considered vulnerable to immediate extinction, is endemic of the region of Paraopeba, Minas Gerais. The objectives of the present study were to compare some morphometric aspects of fruits (n=100) and seeds (n=100), concerning both species and to evaluate the effects of temperature, mechanical scarification (sandpaper) and 12 months storage in refrigerator on germination of both species. The germination experiments took place in germination chambers at constant temperatures of 20, 25, 30 e 35 degrees C and on the alternating temperature 35-15 degrees C both at 12 hours photoperiod and under continuous darkness. Seeds of D. wilsonii were larger than D. mollis, in all the characteristics evaluated, resulting in a clear separation between the two species for the principal components analysis (PCA). Seeds of both species are light insensitive for germination and present tegument dormancy, reverted by mechanical scarification. Non-scarified seeds of D. mollis presented similar germination at all temperatures, while the scarified ones presented higher germination percentages between 20 and 30 degrees C and under the alternated temperature, with a maximum value of 89%. The freshly collected non-scarified seeds of D. wilsonii resulted in similar germination in an ample range of temperature with a smaller value at 20 degrees C. The percentage of germination of the scarified seeds of this species was higher in darkness at 20 degrees C and 35-15 degrees C, with a maximum value of 78%. Stored seeds of D. wilsonii maintained their viability after one year of storage in a refrigerator, while germination tests showed that the temperatures used did not influence the germinability. These results suggest that storage in refrigerator is a good practical means for the ex situ conservation of this species.