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A greenhouse experiment involving four levels of boron (0, 5, 10 and 20 mg B kg -1 ) and the levels of zinc (0, 10 and 20 mg Zn kg -1 ) was conducted in tomato plants (Lycopersicon esculentum L., cv., 'Lale'). Boron toxicity symptoms occurred at 10 to 20 mg kg -1 B levels. These symptoms were somewhat lower in the plants grown with applied Zn. Fresh and dry weights of the plants clearly decreased with applied B. However Zn treatments partially depressed the inhibitory effect of B on the growth. Increased levels of B increased the concentrations of B in plant tissues and to a greater extent in the absence of applied Zn. Both Zn and B treatments caused an increase in Zn concentration in the plants.

Excess of boron in soil and irrigation water is a serious constrain to crop production in many areas of the World as well as in Turkey. A pot experiment was carried out with to screen safflower cultivars in order to investigate the effects of boron toxicity stress on early growth and ions composition. Three safflower cultivars (Carthamus tinctorius cv. Balci, Yenice, Remzi Bey) were grown in pots containing alkaline and potassium rich soil, additionally supplemented with 0, 4, 8, 16, 32, 64 and 128 mg kg -1 boron. Chlorophyll content of all cultivars decreased with excessive boron levels. Plant height, shoot fresh and dry weight significantly increased at 4 mg kg -1 boron level followed by sharp decline with the other treatments. Boron content of cultivars increased and the highest amount was observed at 128 mg kg -1 boron level. Sodium content of all cultivars gradually increased with increase in B concentration. Whereas, potassium and calcium content reduced with increased B. Phosphorus content of all cultivars were least at 128 mg kg boron level. Results revealed that cv. balci appeared to tolerant to boron in soil up to 32 mg kg -1 and can be recommended for growing and breeding material for boron rich soils of Central Anatolia.

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