Water deficit responses of Euterpe edulis Martius seedlings at different growth stages

Abstract

Euterpe edulis plants at two developmental stages (Class A, two-year-old seedlings, and Class B, four-year-old-saplings, with a mean height of 16.0±1.3 and 49.0±3.3 cm, respectively), were subjected to three successive water availability regimes (water deficit, re-watering and subsequent water deficit after re-watering) in greenhouse conditions. We assessed physiological and morphological parameters to detect differences in the water deficit response. Saplings showed a more rapid stomata closure 14 days after the beginning of the regime (DABR) than seedlings (which only showed a response after 17 DABR). Furthermore, the stomata conductance of saplings subjected to the re-watering regime reached the same value as the controls faster (14 DABR) than that of seedlings (25 DABR). When again subjected to water deficit, saplings showed a two-fold higher stomata conductance than the control plants, whereas seedlings showed a five-fold lower value. This response pattern can be attributed to morphological differences between the developmental stages, which is reflected in different hydrodynamic behaviors. Saplings showed a more balanced root/aerial shoot ratio (0.91±0.32), whereas the ratio for seedlings was 0.51±0.17. We conclude that more developed plants are more tolerant to recurrent cycles of water deficit. The results suggest the potential to harden jussara palm plants in nurseries.