ECO-PHYSIOLOGICAL BEHAVIOR OF TAMARIND (TAMARINDUS INDICA L.) IN DRY ENVIRONMENT OF WEST AFRICA (CASE STUDY OF SENEGAL).

Abstract

Water deficit is considered by several authors to be the most limiting factor for agricultural production in the subtropics (Kizito et al., 2006; Porcel and Ruiz-Lozano, 2004; Bader et al., 2006; Logan et al., 2010; Rodriguez-Gamir et al., 2011; Conedera et al., 2011). On woody plants, only a few isolated studies (on Acacia, and combretaceae) exist in the tropical zone south of the Sahara. Noteworthy are the works done on Sahelian forest species, Acacia tortilis (Diouf, 1996), Combretum glutinosum, Guiera senegalensis; Piliostigma reticulatum; Balanites aegyptica, Boscia senegalensis, A. senegal and Ziziphus mauritiana (Fournier, 1995; Kizito et al., 2006; Lufafa et al., 2008). Characterization of plant water functioning is a tool for selecting plants and/or varieties for their tolerance to water deficit (Lufafa et al., 2008; Zhu Qiuan et al., 2011; Logan et al., 2010). It is most often done at young age for ease of use (nursery and early field establishment of seedlings). However, even as adults, woody plants remain dependent on climatic factors such as rainfall (Kisito et al., 2007; Lufafa et al., 2008). It is therefore important to understand the in situ water functioning of adult plants to better explain the depressive effects of such complex water stress at a young age. However, the behavior of plants in situ is influenced by the climatic conditions and the uniformity (age) of the subjects (tamarind plants) to be followed. The present work was carried out on adult T. indica plants in situ in Senegal (Niokhoul in the Sahelian zone and Mbassis in the Sudano-Sahelian zone) and aimed mainly to: (1) understand and describe the physiological water management strategies of tamarind under arid conditions; and (2) understand the impact of this water management strategy on phenology and productivity. The study was conducted in Senegal, characterized by a dry and arid climate. It adopted a field approach (Seghieri, 2010; Conedera et al., 2010) based on adult stands and climatic data collected at the study sites. Ultimately, the adaptation mechanism of tamarind to water deficit would be that of avoidance, described by various authors (Khalfaoui, 1985; Lacape, 1996; Nwalozie and Annerose, 1996; Rouhi et al., 2007; Roussel, 2008; Maes et al., 2009). Indeed, the plant first proceeds to a decrease in water potential (case of the Mbassis stand) and in case of continuous water deficit, it integrates the reduction of the leaf surface by the progressive fall of the leaves and flowers which can go up to the total defoliation (case of the stand of the Sahelian zone in Niokhoul).