ISHS Acta Horticulturae 275: International Symposium on the Culture of Subtropical and Tropical Fruits and Crops
EFFECT OF ROOT TEMPERATURES ON GROWTH OF TWO AVOCADO ROOTSTOCK CULTIVARS |
| Authors: | A.W. Whiley, B.N. Wolstenholme, J.B. Saranah, P.A. Anderson |
| Abstract:
Non-grafted, cloned avocado plants [Persea americana Mill.] of the Mexican [cv Duke 7] and Guatemalan [cv Velvick] ecological races were grown for twelve weeks in sunlit growth rooms with root temperatures controlled at 13, 18, 23 and 28°C. Air temperatures in the rooms were profiled between 28°C day maximum (15h00) and 18°C night minimum (06h00). Root dry mass at the root temperature of 13°C was lower than at 18, 23 and 28°C. There was no significant difference in root dry mass between the two cultivars at any of the root temperatures.
Shoot dry mass was greatest at 18, 23 and 28°C with a significant reduction at 13°C. At the root temperatures of 13 and 23°C cv Velvick produced greater shoot growth than cv Duke 7. Leaf xylem water potential ( | |
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L) became more negative and stomatal conductance (gs) fell during the day regardless of root temperature.
However, at all root temperatures the 
