Effects of drought stress on water consumption characteristics of three Eucalyptus seedlings

Objective  The water consumption characteristics and their differences were estimated underdifferent soil water conditions to provide a guidance for culturing effectively seedlings.

Method The diurnal variation of water consumption (WC) and water consumption rate (WCR) of two kinds of Eucalyptusurophylla × E. grandis (DH33-27 and DH32-29) and E. grandis (H1) clonal seedlings in differentsoil moisture contents were measured using pot experiment, and the water use efficiency (WUE) wasmeasured using Li-6400 portable photosynthesis analysis system, respectively.

Result and conclusion The results showed that E. urophylla × E. grandis DH33-27 seedlings had the highest WC, (162.56 ±8.71) g·plant^-1, among these three Eucalyptus seedlings. When subjected to serious drought, its WCvalue decreased to (10.83 ± 1.01) g·plant^-1 which was the lowest. The similar variation trends of theWCR and WC were found: Two E. urophylla × E. grandis seedlings had high value under sufficient moisture and then decreased sharply under drought stress, but the average WCR of E. grandis still remained high. The diurnal change of WCR of these three Eucalyptus seedlings all followed the curve withone peak in different periods. The order of WUE of these three Eucalyptus seedlings was as follows: E.urophylla × E. grandis DH33-27 > E. urophylla × E. grandis DH32-29 > E. grandis. In conclusion, compared with E. urophylla × E. grandis DH32-29 and E. grandis, E. urophylla × E. grandis DH33-27 has higher photosynthesis and WUE, which is recommended to plant widely in both humid and arid regions.