Leaf gas exchange and water relations in two assai cultivars submitted to water-deficit

Trocas gasosas e relações hídricas em duas cultivares de açaí submetidas ao déficit hídrico

Abstract:

Assai (Euterpe oleracea Mart.) cultivars BRS-Pará (BRS-PA) and BRS-Pai d’Égua (BRS-PDE) were selected for cultivation in upland regions of the Amazon. Given these cultivars were developed from different progenitors, we postulated that they differ regarding water-deficit tolerance. To test this hypothesis, plants of both cultivars were evaluated under well-watered (control) and water-deficit conditions (pre-dawn leaf water potential of – 2.33 MPa). Relative to control, the water-deficit decreased net CO₂ assimilation rate (A) and transpiration by 82% and 86% in both cultivars, while the stomatal conductance (g_s) was reduced by 93% and 87% in stressed plants of BRS-PDE and BRS-PA. The water-deficit improved instantaneous water-use efficiency by 43% in both cultivars, while intrinsic water-use efficiency (A/g_s) increased by 193% and 33% in BRS-PDE and BRS-PA. The water-deficit induced 44% increase in foliar proline and 27% decrease in soluble carbohydrates in both cultivars, while foliar sucrose decreased by 53% in BRS-PA and 16% in BRS-PDE in relation to control. The relative water content in stressed plants of both cultivars was decreased by 8.5% in relation to control. In conclusion, the more efficient stomatal opening control and higher A/gs in BRS-PDE indicate this cultivar better copes with drought than BRS-PA.

Index terms
Instantaneous Water Use Efficiency; Intrinsic Water Use Efficiency; Osmotic Adjustment; Foliar Proline Concentration