THE EFFECT OF THREE ROOTSTOCKS ON YIELD AND FRUITING OF SWEET CHERRY

Three seedling cherry rootstocks were evaluated at Lenswood, South Australia, for their effect on yield and fruit quality of ‘Venus’, ‘Stella’, and ‘Sam’ sweet cherry (Prunus avium L.). Planted in 1980, results from 1990 to 1996 are reported in this paper. Previous results (1985 to 1989) had shown no significant differences in yield, fruit weight or diameter, or proportion of rain cracked fruit. However, results from 1990 to 1996 showed many differences. Over that 7 year period, mahaleb (P. mahaleb L.) and Stockton Morello (P. cerasus L.) rootstocks yielded more fruit than mazzard (P. avium), with average yields of 22.8, 22.7 and 19.2 kg/tree, respectively. In 1990, mahaleb was the highest yielding rootstock and in 1992, it was Stockton Morello. In 1993, 1994 and 1996, all rootstocks had similar yields. In 1991, mazzard produced more fruit than Stockton Morello and in 1995 the reverse occurred. The lowest average yield for all rootstocks occurred in 1993 and was attributed to low temperatures during flowering.
On average, across all 7 years, fruits from trees grafted on mazzard suffered more rain-cracking damage (21.3%) than those grafted on mahaleb (18%) and Stockton Morello (17.9%). Lowest rain crack damage was recorded in 1991, although 1996 had similar levels of damage, and the highest occurred in 1992. These years correspond with the lowest and highest rainfall recordings for December, the main harvest period. Recorded rainfall was 12.4 mm in December 1991 and 164 mm in 1992, the latter being 3 times the average rainfall for that month. In 1990, 1994 and 1995, similar levels of rain damage occurred in fruits on all three rootstocks.
Fruits from trees on Stockton Morello were lowest in average weight in 1995 (6.5 g) and 1996 (8.1 g); there were no differences in fruit weight in other years. The proportion of fruit with a diameter >25 mm also was least for Stockton Morello in 4 of the 7 years. Trees on mazzard and mahaleb had a similar proportion of fruit with diameters >25 mm in 5 out of 7 years.