Seed coat cell turgor in chickpea is independent of changes in plant and pod water potential

Turgor pressure in cells of the pod wall and the seed coat of chickpea (Cic er arietinum L.) were measured directly with a pressure probe on intact pla nts under initially dry soil conditions, and after the plants were irrigate d. The turgor pressure in cells of the pod wall was initially 0.25 MPa, and began to increase within a few minutes of irrigation. By 2-4 h after irrig ation, pod wall cell turgor had increased to 0.97MPa. This increase in turg or was matched closely by increases in the total water potential of both th e pod and the stem, as measured by a pressure chamber. However, turgor pres sure in cells of the seed coat was relatively low (0.10 MPa) and was essent ially unchanged up to 24 h after irrigation (0.13 MPa). These data demonstr ate that water exchange is relatively efficient throughout most of the plan t body, but not between the pod and the seed. Since both the pod and the se ed. coat are vascularized tissues of maternal origin, this indicates that a t least for chickpea, isolation of the water relations of the embryo from t he maternal plant does not depend on the absence of vascular or symplastic connections between the embryo and the maternal plant.