Research Accomplishment Reports 2007

Rootstock and Interstem Effects on Pome- and Stone-Fruit Trees 

J.G. Masabni
Department of Horticulture

 

Project Description

1999 Apple Dwarf & Semidwarf Rootstock Trials: This planting consists of two groups of apple rootstocks, a dwarfing group of eleven rootstocks and six replications, and a semi-dwarfing group of six rootstocks and six replications. The number of root suckers per tree varied significantly among both groups of rootstocks. Trees on CG.3041 and CG.4013 had the least and most root suckers, respectively, among the dwarfing rootstocks. Trees on M.26 EMLA and M.7 EMLA had the least and most root suckers, respectively, among the semi-dwarfing rootstocks. The trunk cross-sectional area varied significantly only among the dwarf rootstocks, while tree mortality and cumulative yield varied significantly only among the semi-dwarf group. Yield in 2005 and average fruit weight did not vary significantly by rootstock for either the dwarf or semi-dwarf group. Trees on the Supporter Series of rootstocks have all survived in the dwarf rootstock planting. Conversely, only 17 percent of the trees on Supporter 4 have survived in the free-standing semi-dwarf trial.

2002 Apple Rootstock Trial: This trial compares nine rootstocks consisting of three clones of M.9, two clones each of B.9 and M.26, and one clone each of Supporter 4 and of P.14. A few trees have been lost to fire blight and wind breakage, but significant differences in tree mortality have not been observed to date. Significant differences were observed for cumulative yield, yield in 2005, fall trunk cross-sectional area, and number of root suckers, but no difference was observed in fruit size as measured by average fruit weight. The combined yield over the past two years was greatest for trees on M.26 NAKB and M.9 Nic29. Scions on M.9 Burg 756 and M.9 Nic29 yielded the most fruit in 2005. P.14 and B.9 Europe rootstocks have produced the largest and smallest trees, respectively, in this trial.

2003 Apple Rootstock and Physiology Trials: Tree survival, yield, average fruit weight, trunk cross-sectional area, and number of root suckers all varied significantly among the trees in the 2003 apple rootstock trial. Trees on CG.5935 yielded the most fruit in 2005. However, only 63 percent of the trees on this and the G.16 rootstocks have survived. Scions on PiAu56-83 are the biggest trees in this trial. For all trees in the physiology trial, the number of fruit left after fruit thinning in the spring was adjusted to 4 fruit per square centimeter of trunk cross sectional area for an average of 33 fruits per tree. No significant differences were observed among the three rootstocks in mortality, yield, trunk cross-sectional area, or number of root suckers. However, fruit size as measured by average weight per fruit was significantly smaller for scions on G.16 rootstocks than it was for those scions on either M.26 or M.9 rootstocks.

Impact

The NC-140 plantings are of utmost importance to Kentucky for gaining access to and testing new rootstocks from around the world. The detailed and objective evaluation of these rootstocks will provide growers with the information needed to select the most appropriate rootstocks for their needs as they become commercially available in the future. Apple Rootstock Plantings provide us with needed information on the adaptability of the slender spindle and the vertical axe training systems to trees grown on our fertile soils. Also, the non-trellised, semi-dwarf group of rootstocks in the 1999 Apple Rootstock planting provides us information on the ability of these rootstocks to support themselves on their own root systems. The 2002 apple rootstock trial will provide information on the differences in performance among clones of rootstocks, and the 2003 apple rootstock trial will provide information on the adaptability of some new rootstocks to climate and soil conditions in Kentucky. Finally, the 2003 physiology trial will provide information on the relationship between different environment sites and crop load and fruit size. The NC-140 trials are regularly used as demonstration plots for visiting fruit growers, extension personnel, and research scientists. The research data collected in these trials will help to establish base-line production and economic records for various orchard system/rootstock combinations which can be later utilized by Kentucky fruit growers.

Publications

Autio, W., T. Robinson, W. Cowgill, C. Hampson, M. Kushad, J. Masabni, D. Miller, R. Quezada, R. Perry, and C. Rom. 2007. Performance of Gala apple trees on strains of B.9, M.9, and M.26 and new Cornell-Geneva, Morioka, and Pillnitz rootstocks: Early results from the 2002 NC-140 Apple Rootstock Trial. Compact Fruit Tree 40: in press.

Autio, W.R., T.L. Robinson, B.H. Barritt, J.A. Cline, R.M. Crassweller, C.G. Embree, D.C. Ferree, M.E. Garcia, G.M. Greene, E.E. Hoover, R.S. Johnson, K. Kosola, J. Masabni, M.L. Parker, R.L. Perry, G.L. Reighard, S.D. Seeley, and M. Warmund. 2007. Early performance of Fuji and McIntosh apple trees on several dwarf rootstocks in the 1999 NC-140 Rootstock Trial. Acta Hort. 732:119-125.

Autio, W.R., T.L. Robinson, B.H. Barritt, J.A. Cline, R.M. Crassweller, C.G. Embree, D.C. Ferree, M.E. Garcia, G.M. Greene, E.E. Hoover, R.S. Johnson, K. Kosola, J. Masabni, M.L. Parker, R.L. Perry, G.M. Reighard, S.D. Seeley, and M. Warmund. 2007. Early performance of Fuji and McIntosh apple trees on several semidwarf rootstocks in the 1999 NC-140 Rootstock Trial. Acta Hort. 732:127-133.

Masabni, J.G., and D.E. Wolfe. 2006. Rootstock and Interstem Effects on Pome Fruit Trees. 2006 Fruit and Vegetable Crops Research Report. University of Kentucky College of Agriculture, Agricultural Experiment Station publication PR-538:43-44.

Masabni, J., R. Andersen, A. Azarenko, G. Brown, J. Freer, D. Hayden, P. Hirst, W. Lay, B. McCluskey, R. Perry, T. Robinson, G. Tehrani, D. Wolfe. 2007. Performance of Plum Rootstocks with Stanley, Valor, and Veeblue as the Scion in the 1990 NC-140 Multi-Site Plum Trial. Journal of American Pomological Society (accepted, October 2007).

Masabni, J., R. Andersen, A. Azarenko, G. Brown, J. Freer, G. Reighard, P. Hirst, D. Hayden, W. Lay, B. McCluskey, T. Robinson, G. Tehrani, D. Wolfe. 2007. Performance of Plum Rootstocks with Stanley, Valor, Veeblue, and Santa Rosa Scions in the 1991 NC-140 Multi-State Plum Trial. Journal of American Pomological Society (accepted, November 2007).