PHOSPHATE DEFICIENCY AFFECTS ACID PHOSPHATASE ACTIVITY AND GROWTH OF TWO WHEAT VARIETIES

The effects of phosphate deficiency on the plant growth and acid phosphatase activity in two wheat cultivars (Triticum aestivum L. cv. 'Bryza' and 'Opatka') were studied. Pi content decreased significantly in the shoots and roots of all plants grown for one to three weeks in the nutrient medium without phosphate (-P). Phosphate starvation affected growth of both wheat cultivars in a similar way: significantly decreased shoot and root mass, especially after three weeks growth on -P medium, even up to 8-11% of control. However the ratio of root/shoot fresh weight of -P plants increased (2-3 times more than control). The shoot height of -P wheat plants decreased to about 50-60% of the control after two to three weeks of culture; less affected by Pi deficiency was root elongationno significant changes were observed for both wheat cultivars during one to three weeks of culture. Phosphate deficiency increased the activity of extracellular and intracellular acid phosphatases in comparison to phosphate-sufficient plants. The increase of intracellular acid phosphatase activity in leaves and roots was generally more significant in 'Bryza' cultivar as compared to 'Opatka', especially after two to three weeks of growth on -P medium. The increase of root surface acid phosphatase activity was the highest for Pi-deficient wheat cv. 'Bryza', after three weeks of culture in the -P medium. Generally, the increase of activity of acid phosphatases secreted by the roots of -P wheat plants was higher than those of intracellular acid phosphatases. These results indicate an important role of acid phosphatases in the acclimation of both wheat cultivars to early Pi deficiency.