EFFECTS OF SALINE IRRIGATION ON MATURE PEAR TREES
Mature Williams Bon Cretien (WBC) pear trees have been irrigated with water at a range of salinities (0 to 1 500 mg NaCl/1) for seven seasons. The watertable was maintained below 2 m by a groundwater pump. There has been no significant effect of salt treatment on mean yield per tree despite higher salt content in the leaves; in January 1988, the mean Na and Cl contents of mid-lateral leaves (dry weight basis) were 21.3 mM/kg and 53.5 mM/kg respectively in the 1 500 mg NaCl/1 treatment compared with 4.3 mM/kg and 8.5 mM/kg respectively in the control treatment. Trees of the 1 500 mg NaCl/1 treatment had a greater proportion of undersized fruit than did the control trees (54% compared with 42%). In February 1987, osmotic potential of the 1 500 treatment was about 0.4 MPa lower than that of the control treatment whilst relative water contents of the two treatments were similar. So there was greater osmotic adjustment in the 1 500 treatment. During December and January, midday CO2-assimilation rate (A) and leaf conductance (g) were similar for control and salt-treated trees. However, in April, when leaf Na and Cl in the 1 500 mg NaCl/1 treatment had risen to 276.6 mM/kg and, 2 56.4 mM/kg respectively, A and g of these salt-treated trees were about 60% of those of the control trees. In 1988, leaf fall began earlier in the 1500 treatment than in the less saline treatments.
Myers, B. A. and West, Dennis W. (1989). EFFECTS OF SALINE IRRIGATION ON MATURE PEAR TREES. Acta Hortic. 240, 279-282