Gas exchange in gariroba palms grown under subtropical conditions

Trocas gasosas em palmeira gariroba cultivada sob condições subtropicais

ABSTRACT

Gariroba palm, native to Brazil, produces bitter heart-of-palm, consumed as vegetable in salads, as well as in other Brazilian recipes. This research was carried out in field condition to evaluate diurnal and seasonal variation of gas exchange of gariroba palms cultivated under subtropical conditions, considering their interrelation with some climate elements. Plants were evaluated within two consecutive years, grown under field conditions and irrigated, spaced 2x1 m. Net assimilation of CO₂ (P_N), stomatal conductance (g_s ), transpiration (E), leaf temperature (T_l ) within the chamber and the photosynthetic photon flux density (PPFD) were evaluated. Water use efficiency (WUE) was estimated by the ratio: WUE = P_N/E. Net CO₂ assimilation (P_N), showed a plateau in May, observed from 9:30 to 14 h, reaching an average of 5.4 μmol m^-2s^-1, then declining toward late afternoon. As far as August is concerned, P_N increased from the early morning until 11 h, reaching the maximum value of 9.0 µmol m^-2s^-1. From then on it decreased reaching 6.0 µmol m^-2s^-1 at 14 h. Gariroba palms cultivated and even under lower autumn and winter temperatures presented gas exchange characteristics consistent to climatic elements.

Keywords:
Syagrus oleracea; photosynthesis; bitter heart-of-palm