A suitable indicator for scheduling pear-jujube (Ziziphus jujuba?Mill.) irrigation?in Chinawas developed based on trunk diameter?fluctuations?(TDF). Parameters derived from TDF?responses to variations in soil?matrix?potential (Ψsoil) were compared under deficit and well irrigation. Maximum daily shrinkage (MDS) increased with higher Ψsoil, whereas daily maximum trunk diameter and daily growth decreased with lower Ψsoil.MDS?signal intensity (actual MDS/reference?MDS) to noise ratio was highest in response to higher and lower Ψsoil. The advantage of MDS in automatic irrigation scheduling compared with other?TDF-derived parameters was its?prompt?reliable response to water deficit, with less effect of phenophase. Based on the MDS signal threshold values, the Ψsoil?without irrigation-related stress was in the range of -40 to -25 kPa during anthesis and setting, and -53 to -35 kPa during fruit development. The MDS signal was?around?1.30 when the Ψsoil?ranged from -80 to -67 kPa during fruit development, indicating?drought?stress. In addition, leaf water use efficiency increased under these conditions, but photosynthetic rate and transpiration rate decreased. Vegetative growth was reduced, but individual fruit weight increased and compensated for yield losses caused by water deficit. These values can facilitate precise irrigation and deficit irrigation of pear-jujube in China.
展开▼
