[Effects of drought stress on the stoichiometric characteristics in different organs of three shrub species]. / 干旱胁迫对3种灌木不同器官化学计量特征的影响.

ABSTRACT

In order to explore how water stress affects the stoichiometric characteristics in leaves, stems, very fine roots (0-1 mm), fine roots (1-2 mm) and thick roots (>2 mm) of three shrub species, we studied the effects of three water treatments [(75±5)%, (55±5)% and (35±5)% of field water capacity (FC)] on the stoichiometric characteristics of different organs of Syringa oblata, Rosa xanthina and Forsythia suspensa in a pot experiment. The results showed that there were significant differences in nitrogen (N) and phosphorus (P) contents, CN, CP and NP of the same organ among the three species. With the intensification of drought stress, there was no significant change of C content in all organs of the three species. The N content increased in leaves, but decreased gradually in stems. The N content in very fine roots and fine roots increased first and then decreased. The P content decreased in leaves and stems, while increased first and then decreased in very fine roots and fine roots. Under drought stress, leaf CN decreased, CP and NP of leaf and stem increased. There was the strongest effect of drought stress on the CN of very fine roots and CP and NP of leaves. There was the least effect of drought stress on CN, NP of thick roots and CP of very fine roots. There was no significant correlation between the contents of C, N in soil and the contents of C, N and P in shrub organs, but soil P content was significantly correlated with the contents of C, N and P in leaves and roots. It was concluded that the relative P limitation in soil was the most important factor affecting the stoichiometric characteristics of shrub organs. Drought had different effects on the stoichiometry of different organs in different shrub species. The stoichio-metry of leaves and very fine roots was more sensitive to drought stress than that of other organs. Drought might affect the stoichiometric characteristics especially related to P in different organs of shrubs, mainly by affecting plant absorption of soil P and its distribution in different organs.