Influence of Maternal Habitat on Salt Tolerance During Germination and Growth in Zygophyllum coccineum

Abstract

Zygophyllum coccineum is a facultative halophyte widely distributed in desert wadis and coastal areas in Egypt. Here, we investigated the influences of maternal habitat on tolerance to salt stress during germination and seedling growth under salinity (0, 100, 200, 400 mM NaCl) of three populations of Z. coccineum from a saline habitat (Manzala coast) and non-saline habitats (Wadi Houf and Wadi Asyuti). In all populations, seed germination started within two days in distilled water but germination indices were reduced significantly with salt level increase. Germination percentage was not significantly greater for seeds from non-saline habitats than for those from the saline habitat under moderate salinity (100, 200 mM NaCl), but only seeds from the saline habitat were able to germinate under high salt stress (400 mM NaCl). Germination recovery was greater for seeds from the saline habitat compared to non-saline populations. At the seedling level, the Manzala population showed the lowest inhibition of shoot length and leaf area under salinity (200 and 400 mM NaCl) compared to non-saline habitats. In the same context, the Manzala population had the maximum chlorophyll a content, superoxide dismutase and esterase activities under salinity compared to non-saline populations, but salinity had a non-significant effect on chlorophyll b between the three populations. Carotenoids were enhanced with the increase of salt levels in all populations. These results suggest the salt tolerance of Manzala population is derived from maternal salinity and adaptive plasticity of this species may play an important role in the wide distribution of Z. coccineum.

Keywords: Zygophyllum coccineum; esterase; halophytes; maternal habitats; seed germination; superoxide dismutase.

Figure 1

Comparison of (a) seed mass and (b) seed length of Zygophyllum coccineum from Manzala coast, Wadi Asyuti and Wadi Houf. Value represents the mean of 100 seeds ± standard error, p-value < 0.05. For variables denoted with the same letter, the difference is not statistically significant.

Figure 2

Germination of Zygophyllum coccineum seeds from (a) Manzala coast, (b) Wadi Asyuti and (c) Wadi Houf in distilled water, 100, 200 and 400 mM NaCl for 15 days. Value represents 3 replicates ± standard error. For variables denoted with the same letter, the difference is not statistically significant.

Figure 3

Germination rate index of Zygophyllum coccineum seeds from Manzala coast, Wadi Asyuti and Wadi Houf in distilled water, 100, 200 and 400 mM NaCl for 15 days. Value represents the mean of 3 replicates ± standard error. For variables denoted with the same letter, the difference is not statistically significant.

Figure 4

Germination percentages of Zygophyllum coccineum seeds recovered from 100, 200 and 400 mM NaCl for 15 days. Value represents the mean of 3 replicates ± standard error. For variables denoted with the same letter, the difference is not statistically significant.

Figure 5

Influences of different salt concentrations (0, 100, 200 and 400 mM NaCl) on shoot length in Z. coccineum for 45 days. Value represents the mean of 5 replicates ± standard error, p-value < 0.05. For variables denoted with the same letter, the difference is not statistically significant.

Figure 6

The effects of different salt concentrations (0, 100, 200 and 400 mM NaCl) on leaf area in Z. coccineum for 45 days. Value represents the mean of 5 replicates ± standard error, p-value < 0.05. For variables denoted with the same letter, the difference is not statistically significant.

Figure 7

Effects of 45 days salt treatments (0, 100,200 and 400 mM NaCl) on chlorophyll a in Z. coccineum from Manzala, Wadi Asyuti and Wadi Houf. Value represents the mean of 3 replicates ± standard error, p-value <0.05. For variables denoted with the same letter, the difference is not statistically significant.

Figure 8

Effects of 45 days salt treatments (0, 100, 200 and 400 mM NaCl) on chlorophyll b in Z. coccineum from Manzala, Wadi Asyuti and Wadi Houf. Value represents the mean of 3 replicates ± standard error, p-value < 0.05. For variables denoted with the same letter, the difference is not statistically significant.

Figure 9

The effects of different salt concentrations (0, 100, 200 and 400 mM NaCl) on Chl a/b in Z. coccineum for 45 days. Value represents the mean of 5 replicates ± standard error, p-value < 0.05. For variables denoted with the same letter, the difference is not statistically significant.

Figure 10

Effects of 45 days salt treatments (0, 100, 200 and 400 mM NaCl) on carotenoids in Z. coccineum from Manzala, Wadi Asyuti and Wadi Houf. Value represents the mean of 3 replicates ± standard error, p-value < 0.05. For variables denoted with the same letter, the difference is not statistically significant.

Figure 11

Esterase activity of Z. coccineum plants after 45 days incubation under 0, 100, 200 and 400 mM NaCl.

Figure 12

Superoxide dismutase activity of Z. coccineum plants after 45 days incubation under 0, 100, 200 and 400 mM NaCl.