Date of this Version
Pine voles and meadow voles exhibited differential preferences for various Malus clones. When damage to dormant stems in a 24-hr test was assessed by either a graded damage scale or percentage consumption by weight, pine voles preferred Golden Delicious, M.9, and M.26 and consistently avoided M.x sublobata PI 286613 ("613") and related clones and Robusta 5. Dehydrating stems magnified the disparity among cultivars, as attractive stems continued to suffer extensive damage, while 613 became even less palatable. In the autumn phase all varieties showed increased acceptance. Meadow voles, like pine voles, exhibited differential acceptance of cultivars, but their preferences differed somewhat from pine voles in that they extensively damaged Robusta 5.
When bark and pulp portions of rootstocks were separately presented to pine voles in 1 hr tests, weight consumed followed expected varietal preferences. With dormant stocks, significantly more bark was consumed than pulp in both 613 and Golden Delicious samples, and, in both fractions Golden Delicious was consumed more than 613. In autumn-cut stocks Golden Delicious was preferred to three other varieties overall, as was its pulp fraction.
Humans readily detected textural contrasts among rootstocks, some of which can be measured during the dormant phase as lower densities and higher water content for the extremely preferred rootstocks. Humans also reported taste differences among cultivars, describing rootstocks and fragments as bitter more often for Golden Delicious and 613 than for Robusta 5 and M.9. Taken together, these rootstock data suggest that stem texture may be a primary factor for rootstock acceptability.
Taste probably also plays a role in rootstock preferences. Pine dowels soaked in fruit extract, sucrose, or quinine solutions or water or oil and individually presented to paired pine voles for 24 hr tests were gnawed differentially with enhanced gnawing for oil and extract-treated dowels, and less gnawing of quinine-treated dowels.