Journal of Food, Agriculture and Environment

Drought, salinity and temperature induced responses to photosynthesis in Conocarpus lancifolius

Author(s):

A. Redha, N. Al-Mansour, P. Suleman, R. Al-Hasan, M. Afzal*

Recieved Date: 2011-12-06, Accepted Date: 2012-04-28

Abstract:

Present study was initiated to determine the influence of four different abiotic stressors on non-native Conocarpus lancifolius in the semi-arid environment of Kuwait. Abiotic stress is known to affect photosynthetic (Ps) apparatus and accumulation of competitive solutes. Therefore, we measured photosynthetic pigments and polyols like sugars, starch and carotenoids under variable abiotic stress conditions. Photosynthetic pigments (PsP) are adversely affected by free radicals produced in Ps membranes, cytosol, and mitochondria. Therefore, in PEG exposed plants, PsP significantly decreased Chl a from 2.45 ± 0.023  to 1.82 ± 0.07; Chl b from 1.87±0.074  to 1.48±0.043 and phaeophytin from 3.13±0.02 to 2.63±0.03 mmol g-1 fw. PsP, Chl a, Chl b and pheophytin also decreased significantly in response to 1.7 M sodium chloride to 2.10±0.67,  1.59±0.043,  2.84±0.051  mmol g^-1 fw, respectively. The Chl a/Chl b ratio increased from 1.29 to 1.33 with increasing salinity. Auxiliary non-photochemical quenching (NPQ) pigments such as carotenoids also decreased significantly with salinity and drought but increased with increasing temperature. An increase in temperature stress, resulted in a significant increase in PsP. As a result, Chl a, Chl b and pheophytin increased to 3.91±0.22, 2.62±0.10 and 4.32±0.15 mmol g^-1 fw indicating Ps activity and plant growth with increasing temperature. This was supported by an increase in biomass of the plants exposed to elevated temperature. Measurement of the leaf Ps activity and solute potential (ψ_π) electron transport rate (ETR) confirmed our results for the variation in Ps activity of the plant with increased temperature. Our results show that the growth and development of C. lancifolius is supported by elevated temperature but suffered from drought and salinity stress. Differential response of the plant to abiotic stress may be due to differential regulation/expression of antioxidant enzymes in the plant.

Keywords:

C. lancifolius, drought, photosynthesis, salinity, temperature

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Journal: Journal of Food, Agriculture and Environment
Year: 2012
Volume: 10
Issue: 2
Category: Environment
Pages: 1320-1325

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