Root Growth and Spatio-Temporal Distribution of Three Common Annual Halophytes in a Saline Desert, Northern Xinjiang

Vegetation covers approximately 20% of the saline deserts in Xinjiang. The dominant life forms are perennial herbs, followed by annual herbs. Patches of annual halophytes are distributed among halophytic shrubs. Compared with succulent halophytic shrubs, annual halophytes confront more serious survival risks, for example, drought, saline, strong solar radiation, and high temperature. In order to accomplish generation succession and inhabit the desert environment, annual halophytes have to grow a new root system each year, and the characteristics of their root development and distribution determine their growth and reproduction for the current year.

Root ecology is an active field in current ecology research. Most of the existing researches into the characteristics of halophyte root growth have focused on perennial halophytes, mainly involving their horizontal and vertical root distribution. However, research about the root development characteristics over time is lacking, and research into the root spatial and temporal distribution characteristics of annual halophytes is even less.

Salsola subcrassa, Suaeda acuminate, and Petrosimonia sibirica are three common annual halophytes found in the saline deserts of northern Xinjiang, and their characteristics of root growth and distribution are representative of their class. Therefore, researchers studied the root growth and spatio- temporal distribution in the 0–100 cm soil profiles of the three common annual halophytes in 2009 and 2010.

The results showed that the root systems of the three halophytes were of the taproot type, vertically distributed in the 90-cm soil profile, and were deepest in late July. Their taproots reached maximum depth rapidly, early in the growth period, but with rare lateral roots. They were then dug out in an orderly way, from bottom to top, exhibiting vertical development first and then horizontal development. The distribution of specific root length, which reflects the characteristics of the feeder root, was gradually increased from top to bottom, whereas root weight displayed an opposite distribution pattern. The root length distribution of the three halophytes was concentrated (62% to 76%) in the middle soil profile (20–60 cm), with less distribution in the surface (0–20 cm) and bottom (60–90 cm) soil profiles. The results indicated that the roots of the three annual halophytes grew rapidly into the deeper soil layer after germination, which ensured the plant survival and uptake of water and nutrition, and thus built up a strong tolerance to an arid, high-salt environment.

The result has been published on Journal of Arid Land, 2012, 4(3): 330-341. The paper is also archived at http://jal.xjegi.com/EN/abstract/abstract154.shtml.