ABSCISIC-ACID, TEMPERATURE AND SALINITY INTERACTIONS ON GROWTH AND SOME MINERAL ELEMENTS IN CARTHAMUS PLANTS

Growth and contents of sodium (Na), potassium (K), calcium (Ca), magne sium (Mg), chloride (Cl), phosphorus (P) and sulphur (S) in shoot and root tissues of Carthamus tinctorius plants were measured at combinati ons of four nutrient solution osmotic potentials (Psi(s) = 0, -0.3, -0 .6 and -0.9 MPa) induced by NaCl and CaCl treatments, three constant t emperatures (T) ranging from 15 to 35 degrees C and four abscisic acid (ABA) concentrations (0, 10, 50 and 100 mg L(-1)). Unstressed and str essed plants grown in optimal temperature conditions (25 degrees C) ma intained higher growth rates (dry mass production) than plants grown u nder low and high temperatures (15 and 35 degrees C respectively). Sho ot and root growth (dry mass production) were largely inhibited by sal inity but the magnitude of growth inhibition was temperature dependent . Safflower plants respond to salinity stress by increases in Ca, Cl a nd to a lesser extent Na in their shoots and roots and by a decrease i n the ratio of fresh to dry weight. The ratio of K/Na was decreased pr ogressively on salinization. With stressed plants, ABA application red uced the toxicity of salt treatment, improved K uptake under salinity, effectively increased K/Na ratio and helped the plants to avoid Na to xicity and sometimes enhanced growth. The effect of ABA on the growth was more pronounced at optimum temperature (25 degrees C). The associa tion between the internal mineral element concentrations was largely a ffected by ABA application and temperature change but a wide fluctuati on in response was noticed. The effects of single factors (Psi(s), T a nd ABA) on the growth and mineral contents were statistically signific ant. Also, bifactorial (Psi(s) x T, Psi(s) x ABA and T x ABA) and thre e factorial (Psi(s) x T x ABA) interactions significantly affected the parameters. Further statistical treatment of the data (coefficient of determination eta(2)) led to four important findings: (1) Salinity (P si(s)) was dominant in affecting Ca and Cl contents in both shoot and root as well as root Na content. (2) Temperature (T) had a dominant ef fect on growth, shoot K, Mg, P, S and root P, and S contents (3) The s hare of Psi(s) x T x ABA interaction was dominant for root Na and Mg c ontents. (4) The single factors and their interactions had a dual role in their subsidiary effects.