Physiological behaviour vis-a-vis water logging conditions in some tree species

Strip plantations of two rows of ten trees species (Eucalyptus tereticornis clone-tO, Eucalyptus tereticornis cIone-t30, Eucalyptus tereticornis cIone-3, Eucalyptus hybrid clone (Eucalyptus tereticornis x Eucalyptus camaldulensis), Tamarixaphylla, Prosopis julijlora, Callistemon lanceolatus, Melia azedarach, Terminalia arjuna and Pongamia pinnata) each 60 meters apart were raised on field bunds at the CCS Haryana Agricultural University, Hisar animal fodder production farm area, comprising of about 30 acre' of water-logged pasture land along with the Balsamand canal. To monitor water table fluctuations immediately beneath the plantations due to evapotranspirational-drainage (ED), observation wells were dug on each of the bund between the two ro~s of trees. Morpho-physiological ED traits like tree height, diameter at breast height (DBH), leaf area index (LAI), stomatal density, stomatal conductance (gs), transpiration rate, potometric water loss (PWL), relative water content (RWC), excised leaf water loss (ELWL) and dimensions of the water conducting elements (tracheids and vessels) were also studied. Palpable fluctuations in the water table immediately beneath each phintation on a 24 hour diurnal cycle were observed and the magnitude of depression of water table beneath each plantation was taken as the ED potential of tree species. Amongst the different tree species ED, as determined by decline in water table beneath the plantation, was in the order of : Eucalyptus Clone-tO (42.00mm) Eucalytpus hybrid (41.75mm) Eucalyptus Clone-t30 (22.50mm) Tamarix aphylla (22,00mm) Prosopis julijlora (l9.25mm) Eucalyptus Clone-3 (l6.50mm) Callistemon Ian ceo latus (1l.75mm) Melia azedarach (1l.50mm) Terminalia arjuna (5.50mm) Pongamia pinnata (5.25mm). Correlation analysis of ED potential with other parameters showed that ED potential had a significant positive correlation with LAI. Tree height, DBH, stomatal density and leaf transpiration rate also bore a significant positive correlation with ED potential. However, correlation trends with other physiological traits like PWL, RWC, ELWL and length and width of water conducting elements were not consistent. Our results indicate that species like Eucalyptus tereticornis cIone-lO and Eucalyptus hybrid are fast EDs primarily due to their ability to display large leaf area as compared to slow EDs like Terminalia arjuna and Pongamia pinnata where leaf area development is poor.