Growth and potassium transport in common and durum wheat as affected by aluminum and nitrite stress

Aluminum (Al) toxicity has been identified as one of the most important fac tors limiting plant growth in acid soil. Besides Al, nitrite (NO2-) may als o be a significant stress factor in an acid environment. The objective of t his study was to examine the effects of Al and NO2- stress on the growth an d potassium (K+) uptake of roots and their transport toward the shoots of a n Al-resistant common wheat (Triticum aestivum L. cv. Jubilejnaja 50) and a n Al-sensitive durum wheat (T. durum Desf. cv. CK Betadur) grown in 0.5 mM CaSO4 solution at pH 4.1 or 6.5. Root elongation of durum wheat was inhibit ed with 30% at 10 muM AlCl3 treatment, while this low Al-concentration did not show a significant effect on root growth of common wheat. In all cases shoot growth was not influenced under low-salt conditions by 10 muM AlCl3, but exposure to 100 muM KNO2 (alone or in combination with Al) had a defini te stimulatory effect on growth. Aluminum was found to stimulate the K+(Rb- 86) influx in short-term (6 h) experiments, but to inhibit it in long-term (3 days) experiments. This treatment was thought to damage the plasma membr ane. When 10 muM 2,4-dinitrophenol was present in the uptake solution the A l-stimulated K+ uptake stopped even in short-term experiments. In the case of nitrite and nitrite + Al treatment combinations, however, a striking inh ibition was observed in the K+(Rb-86) influx and the K+ concentration of th e roots and shoots of both species.