Table 3. The effects of potassium deficiency on activity of GPX and SOD in cotton xylem sap.

Treatment	GPX activity		SOD activity
	U ml−1 xylem sap	U μg−1 protein	U ml−1 xylem sap	U μg−1 protein
NK	130.5**	16.3**	2.6**	0.32**
LK	16.5	6.0	0.2	0.07

Emerging cotton seedlings in wet sand were transferred to a normal solution, grown for 3 d, and separated into a K-deficient solution and a new normal solution and grown for 7 d. These cotton seedlings were used for xylem sap sampling and index determination. Means within each column followed by the ** are significantly different according to t-test, p < 1%, n = 6.