Table 1.

Effects of alkali stress on the amounts of mineral elements in young and old leaves of cotton seedlings.

Treatment		Control		Alkali stress
Samples		Young	Old	Young	Old
Mineral Element	Na	20.04 ± 0.38	21.90 ± 4.22∗	87.89 ± 2.63∗∗	211.74 ± 13.30∗∗
	K	513.29 ± 23.84	470.60 ± 19.72∗	477.26 ± 21.05	386.94 ± 28.34
	Ca	217.61 ± 16.65	857.51 ± 29.43∗∗	183.24 ± 14.24	864.38 ± 33.28∗∗
	Mg	74.89 ± 6.78	186.21 ± 10.72∗∗	70.24 ± 8.33	187.13 ± 11.92∗∗
	Fe	1.94 ± 0.18	3.81 ± 0.27∗	2.11 ± 0.18	3.33 ± 0.31∗
	Cu	0.22 ± 0.02	0.21 ± 0.02	0.60 ± 0.03∗	0.31 ± 0.03
	Zn	0.55 ± 0.03∗	0.26 ± 0.03	0.66 ± 0.02∗∗	0.22 ± 0.02
	Mn	0.48 ± 0.02	1.40 ± 0.12∗∗	0.51 ± 0.02	1.55 ± 0.13∗∗

The values are the means ± SE of five biological replicates, and each replicate consisted of a pool of five plants. Significant difference between organs under similar stress condition was determined by T-test and marked as ^∗P < 0.05 and ^∗∗P < 0.01. Significant difference between control and alkali stress in the same organs was determined by T-test and marked as ^∗P < 0.05 and ^∗∗P < 0.01. The seedlings were subjected to 80 mM alkali stress (NaHCO₃:Na₂CO₃ = 9:1; pH = 9.06) for 6 days.