Resumo

REDHA, A; SULEMAN, P; AL-HASAN, R  e  AFZAL, M. Responses of Conocarpus lancifolius to environmental stress: a case study in the semi-arid land of Kuwait. Phyton (B. Aires) [online]. 2012, vol.81, n.2, pp.181-190. ISSN 1851-5657.

Cococarpus lancifolius Engl. grows wild in Djibouti, Somalia and East Africa, and South Asia. The species was introduced into Kuwait, where it is exposed to several stresses: oil pollution, salinity, high temperature and harsh climatic conditions. These conditions are prevalent in its semi-arid environment. In this study, the impact of salinity (2, 6 and 10%), temperature (20, 30 and 40 °C), polyethylene glycol (10, 30 and 60%) and drought has been investigated on C. lancifolius. Proline (Pro) accumulation (5.5 ± 0.03 µg/g dry weight; p=0.05-0.005), protein (16.47 ± 0.052 mg/g; p=0.001), free amino acids (10.92 ± 0.082 mg/g; p=0.006) and lipids (116.05 ± 2.17 µg/g; p=0.05) were measured in plants irrigated with 60% polyethylene glycol (PEG) for 6 days. Similar increases in the accumulation of osmolytes were observed under water deficit, NaCl, and temperature-stressed plants. Accumulation of osmolytes was correlated with photosynthetic capacity and electron transport rate. Fifteen different phospholipids were detected in leaf extracts by TLC and 6 major fatty acids were identified by GC/MS analyses. On day 4, the omega-3 fatty acid, linolenic acid was observed the predominant fatty acid present at 61.32% in the 10% PEG-treated plants. The high concentration of this omega-3 fatty acid may help C. lancifolius to adapt to semi-arid conditions in the State of Kuwait. Implications of this study may highlight sustainability of C. lancifolius in the Middle East, African peninsula and other semi-arid regions of the world.

Palavras-chave : Conocarpus lancifolius; Drought; Electron transport rate; Environmental stress; Salinity; Temperature; Photosynthesis.

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