Reproductive biology of Caryocar brasiliense (Caryocaraceae) in preserved and degraded Cerrado areas in Brazil

Abstract

This study aimed to characterize the reproductive system and determine the importance of pollinators for fruit production of Caryocar brasiliense, an economically important tree, in preserved and degraded Cerrado areas in southeastern Brazil. For this purpose, we performed pollinator exclusion experiments to determine the frequency of self- and cross-pollination, and to determine fruit set. In general, fruit set was extremely low; only 2.92% and 2.71% of the flowers developed into fruits in the degraded and preserved areas, respectively. Fruit sets by manual cross-pollination and natural (open) pollination were higher than self-pollination in both areas. Pollen deposition was significantly higher at night and in the preserved area, although a relatively high amount of pollen grains is found in the stigmas during the day. The number of ripened and aborted seeds did not differ among areas, but fruits and seeds were heavier in the degraded area than in the preserved area. The abortion level was very high (64.5%), which may be related to low pollen quality due to selfing. Our study presents evidence that Cerrado degradation affects the reproductive biology of C. brasiliense, but whether such effect is a consequence of pollinator decline in degraded areas remains to be determined.