Abstract:

Halogeton arachnoideus， Salsola ruthenica and Bassia dasyphylla are the dominant plants in the herb layer of artificial wind-breaking and sand-fixing vegetation in the desert-oasis ecotone， and they play an important role in maintaining the stability of the ecolosystem function in the transition zone. We studied the above three Chenopodiaceae annuals in the desert-oasis ecotone of Hexi Corridor， and through extensive sampling in the field， the characteristics of module growth and biomass allocation of the three species at different stages of the vegetative growth period were examined. The quantitative characters and biomass allocation of both above-ground and below-ground modules were analyzed， to reveal the growth strategies of the three species at different growth stages and provide reference for further understanding of their ecological adaptation mechanisms and development of conservation initiatives for the desert ecosystem. It was found that： 1） During the vegetative growth period， the three species differed in the patterns of variation in component growth and biomass accumulation. Above-ground and below-ground biomass showed strong variation with similar coefficients of variation， and leaves and lateral roots had the greatest variability in formation of above-ground and below-ground modules. 2） The module growth and biomass accumulation of the three species differed significantly at different stages of the vegetative growth period （P<0.05）. The growth of primary roots mainly occurred in early and mid-vegetative growth， while the growth of stems， leaves， branches and lateral roots mainly occurred in mid- and late-vegetative growth. 3） The quantitative traits of above-ground modules （stem height， branch number and leaf number） and the above-ground biomass of the three species showed an allometric relationship during the vegetative growth period， while the quantitative traits of below-ground modules （main root length and lateral root number） showed the allometric relationship in early growth， and the relationship was not significant in mid- and late-vegetative growth. 4） The root∶shoot mass ratio （R∶S） of the three species decreased gradually as the vegetative growth period progressed. The above-ground biomass distribution ratio was more than 86%， and the below-ground biomass distribution ratio was less than 14%， and larger plants have lower R∶S.

Key words: Chenopodiaceae, herbs, vegetative growth period, module, biomass allocation