Under ground: what pH favors germination and the root growth of Zeyheria tuberculosa (Vell.) Bureau ex Verl.

This work aimed to examine the germination and initial growth of Zeyheria tuberculosa (Vell.) Bureau ex Verl. seedlings at different pH values. pH of the deionized water was adjusted with hydrochloric acid and/or sodium hydroxide to 4.7, 5.7, 6.7, 7.7 and 8.7. The following parameters were evaluated: final germination percentage (GP), germination speed index, time required for 50% germination, germination rate, viability of the remaining seeds and length of the radicle. All parameters were reduced in alkaline pH. Maximum germination of 94% was reached in the treatment control, followed by pH 4.7. At alkaline pH (7.7 - 8.7), GP was 43 and 31%, respectively. Therefore, at these pHs, germination was reduced. We provided direct evidence that pH is a limiting factor for germination and for the radicle growth of Z. tuberculosa seedlings. In addition, we show experimental evidence of why this species is widely distributed in the Cerrado biome, where the soils are more acidic, and the relationship between soil composition and high germination in acidic medium was corroborated with this study. We suggest that the germination test at different pHs be included in reforestation programs with native species to predict the establishment of seedlings in soils with different pH.