Tropicultura (Jan 2000)
Ecophysiological Analysis of Drought and Salinity Stress Quinoa (Chenopodium Quinoa Willd.)
Abstract
We have studied the relative influence of drought and salinity stress, with similar soil water potentials on growth, water relations and photosynthetic rate of quinoa (Chenopodium quinoa Willd.), testing at the same time certain techniques of stress physiology studies. As treatments, we have imposed two levels of salinity stress (S1 = 3852, 8 mg. V-1 NaCI and S2 = 8051.2 mg. V-1 NaCI) and two of levels of drought stress with-0.159 MPa (D1) and -0, 279 MPa (D2) of soil water potentials (f^), and the control (c) treatment without stress (65 % of volumetric soil water content, i. e. ¥m = -0.059 MPa). Our results of the greenhouse experiment have shown that quinoa has better relative and absolute growth rate in saline conditions, and the plant have developed adaptations mechanisms to drought through higher water use efficiency and high root/shoot ratio. The stomatal resistance and leaf water potential were higher as higher were the stress conditions. The variable chlorophyll fluoresence to maximal chlorophyll fluorescence-ratio (Fv/Fm) and the fluorescence quenching analysis (photochemical : qP and non-photochemical : qN) have shown the plants under drought stress are less protected against photoinhibition. Finally the use of Dynamic Diffusion Porometer has limitations for studies of plants species with salt bladders as quinoa.
