[A preliminary study on salt contents of soil in root-canopy area of halophytes].
The results showed that among the 27 sampling sites, the salt content in rhizosphere of herbaceous halophytes increased at 7 sites and decreased at 20 sites. The variation of soil salt content in the RUE micro-area of shrubby halophytes was related to the growth status of the plants. The salt content in rhizosphere decreased a little at the early stage of plant development, but that in RUE micro-area tended to increase and accumulated most quickly at the site of the canopy edge soil. An obvious variation of salt components was found in the RUE micro-area of different types of halophytes. The Na+/K+ ratio tended to decrease in succulent halophytes and salt secrete halophytes. Among 53 sampling sites, only 14 sampling sites had a higher ratio of Na+/K+ in rhizosphere soil than in background soil, and only 10 sampling sites had a higher ratio of Na+/K+ in canopy-under soil than in background soil. However, the Na+/K+ ratio in the canopy edge soil of Tamarix and Nitraria tended to increase when they grew weakly. By contraries, the Na+/K+ ratio in the rhizosphere was higher than that in background soil at 3 of 4 sampling sites of Phragmites australia, which indicated that the Na+/K+ ratio in the rhizosphere of exclude halophytes tended to increase. The variation of SO4(2-)/Cl- ratio in the RUE micro-area was different in the 3 types of halophytes. For salt secrete halophytes, it decreased obviously in rhizosphere soil, canopy-under soil and canopy-edge soil; for succulent herbaceous halophytes, it tended to increase in rhizosphere soil; and for succulent shrubby halophytes, it tended to decrease in rhizosphere and in canopy-under soil, and tended to increase in canopy-edge soil. The SO4(2-)/Cl- ratio had no big change for exclude-halophytes. The reduction of the salts in rhizosphere of herbaceous halophytes was mainly because of their plant uptake, and the accumulation of salts in the RUE micro-area of shrubby halophytes was because the salt absorbed from the around soil returned to the RUE micro-area again. Because of the selective uptake by plant, the salt component varied with different types of halophytes. Most halophytes except Phragmites australia take more Na+, and hence the Na+/K+ ratio in the rhizosphere tends to decrease. The SO4(2-)/Cl- ratio in the RUE micro-area of salt secrete halophytes trended reduce, mainly because this type of halophyte can secrete more Cl- with its growth.
Xi
Jinbiao
J
Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China. xijinbiao2001@yahoo.com.cn
Zhang
Fusuo
F
Chen
Yang
Y
Mao
Daru
D
Yin
Chuanhua
C
Tian
Changyan
C
D002712:Chlorides / Q000032:analysis*; D018517:Plant Roots / Q000737:chemistry*; D011188:Potassium / Q000032:analysis*; D012964:Sodium / Q000032:analysis*; D012987:Soil / Q000032:analysis*; D013431:Sulfates / Q000032:analysis*
D002712:Chlorides; D012987:Soil; D013431:Sulfates; D012964:Sodium; D011188:Potassium