Water uptake from different soil depths for halophytic shrubs grown in Northern area of Ningxia plain (China) in contrasted water regimes

Figures & data

Figure 1. Daily rainfall recorded from 1 April to 5 July, 2010 in Xidatan. Solid columns represent daily rainfall, hollow columns represent irrigation. Arrow points to the data when soil water, groundwater, plant xylem water were sampled.

Figure 2. Soil water content, salt content, and pH in soil profile of shrubbery on 28 May (solid line) and 4 July (dotted lines), 2010.

Figure 3. δ¹⁸O values of soil water (0–200 cm), groundwater (GW), well water (WW), and rain water (RW) in Xidatan.

Figure 4. (A–B) δ¹⁸O and δD of environmental and plant xylem water sampled at field site and their relationship with Arid Northwest China local meteoric water line (ANC LMWL) in Northwest China.

Table 1. Relationship among soil water hydrogen and oxygen composition, soil water content, soil salt content and pH.

	Soil water δD BI	Soil water δ^18O BI	Soil water δD AI	Soil water δ^18O AI	Soil water content BI	Soil water content AI	Soil salt content BI	Soil salt content AI	Soil pH BI	Soil pH AI
Soil water δD BI	1.00
Soil water δ^18O BI	0.99**	1.00
Soil water δD AI	0.04	0.17	1.00
Soil water δ^18O AI	0.06	0.16	0.91**	1.00
Soil water content BI	−0.66*	−0.69*	−0.23	−0.16	1.00
Soil water content AI	−0.69*	−0.72**	−0.26	−0.17	0.93**	1.00
Soil salt content BI	−0.38	−0.32	0.55	0.59*	0.32	0.32	1.00
Soil salt content AI	0.02	0.08	0.58*	0.59*	0.27	0.12	0.71**	1.00
Soil pH BI	−0.64*	−0.66*	0.06	0.07	0.47	0.41	0.65*	0.38	1.00
Soil pH AI	−0.68*	−0.67*	−0.06	−0.14	0.54	0.62*	0.50	0.22	0.78**	1.00

Note: Asterisk represents the significance of coefficient, *P<0.05, **P <0.01. BI and AI represent before irrigation and after irrigation.

Table 2. Water uptake rate of potential sources for four shrubs in Xidatan (mean (minimum–maximum)).

		Species of shrubs
Water sources		δ^18O	20-year-old Tamarix ramosissima, Ledeb.	3-year-old Tamarix ramosissima Ledeb.	3-year-old Lycium barbarum L.	3-year-old Atriplex canescens
Before irrigation (May 28)
Soil depth (cm)	0–40	−6.39	10.9 (0–24)	90.6 (85–99)	71.4 (62–81)	67.7 (58–77)
	40–140	−8.96	46.8 (0–100)	5.1 (0–15)	15.6 (0–38)	17.7 (0–42)
	140–200	−9.47	42.4 (0–87)	4.2 (0–13)	12.9 (0–31)	14.6 (0–35)
After irrigation (July 4)
Soil depth (cm)	0–40	−9.79	34.0 (0–83)	6.0 (0–18)	6.5 (0–19)	27.4 (0–69)
	40–140	−8.60	36.4 (17–56)	88.8 (82–100)	87.9 (81–100)	48.8 (31–68)
	140–200	−9.97	29.6 (0–72)	5.2 (0–16)	5.6 (0–17)	23.8 (0–60)

Figure 5. Net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), and intrinsic water use efficiency (Pn/gs) of four shrubs measured before irrigation (28 May) and after irrigation (4 July), 2010 (mean±SD; n=6). Different capital letters and lowercases represent significant differences among different measuring times (p<0.05 and p<0.01), respectively.

Figure 6. Twig predawn (ψ_pre, A) and midday (ψ_mid, B) water potentials of four shrubs measured before irrigation (28 May) and after irrigation (4 July), 2010 (mean±SD; n=5). Different capital letters and lowercases represent significant differences among different measuring times (p<0.05 and p<0.01), respectively.