Al-Absi K., Mohawesh O. and Tadros M. 2010.

 Abstract

 The effect of beta-pinene polymer base Vapor Guard surround type film antitranspirants on plant gas exchange parameters (stomatal behavior, carbon assimilation and transpiration), and biochemical parameters (chlorophyll and proline) of Orange (Citrus sinensis L.) cultivars, namely 'Washington Navel', 'Red Blood' and 'Shamouti' under progressive water deficit were studied. The plants subjected to three progressive drought by allowing the 25 %, 50% and 75% of available water (AW_25%, AW_50%, and AW_75%) to be depleted to identify genotypic differences of three Orange cultivars to water deficit in absence or presence of antitranspirants by evaluating the effect of water stress and antitranspirants (ATs) on gas exchange and biochemical parameters. The results showed that a decline in the tolerance of oranges grown under severe water deficit stress, corresponded with reduction in the gas exchange parameters measured and the analyses of chlorophyll and proline concentration. Considerable genotypic variation in drought tolerance was observed. It appears that the antitranspirant compounds did not show any effective results on the stomatal stomatal conductance and leaf water relations. Also, inhibited their capacity to improve the physiological status of the plants.

  (Submitted to Advance in Horticultural Science).

key words: Antitranspirant, Orange genotypes, water stress, water availability, gas exchange.