Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 7, 2001
Publication Date: N/A
Interpretive Summary: Smaller, more efficient peach trees are needed in order to increase peach production and to reduce inputs such as pesticides. Peach trees with different shoot growth habits have been previously developed by breeders, but little is known about their root systems. These trees may have unique root systems that could be useful for the development of size controlling rootstocks and self-rooted trees that could be used in high density orchar systems. This research determined shoot and root characteristics of four peach tree canopy structures (Compact, Dwarf, Pillar, and Standard). We found that there were fundamental differences in root as well as shoot architecture among growth habits that can affect their use in peach breeding programs as fruiting or rootstock varieties. For example, Compact trees grew nearly 50% more fibrous roots than Pillar and Standard trees and they had many more branches in the canopy creating a smaller but denser tree. Pillar trees had less weight of roots than Compact and Standard trees, but Pillar trees with their narrow canopies had 3-times more leaf surface within the canopy than Company and Standard trees. While the significance of these differences remains to be investigated, it is clear that these new tree types with their unique root and shoot structures will provide new opportunities to develop and grow novel, productive peach varieties. These varieties will be able to better utilize light, water, and nutrients with less inputs of chemicals such as pesticides and fertilizers.
Technical Abstract: Shoot and root characteristics of four peach tree (Prunus Persica (L.) Batch.) growth habits (Compact, Dwarf, Pillar, and Standard) were studied. Compact tree leaf number (1350/tree) was twice but leaf area (6 cm2/leaf) was half that of Pillar and Standard trees. The number of lateral branches in Compact trees (34) was nearly 3-times more than in Pillar and Standard trees. The leaf area index (Lai) of Pillar trees was greater than Compact and Standard trees (13 compared with 4 and 3, respectively) due to a narrower crown diameter. Dwarf tree shoots were distinct with few leaves (134 per tree) and a large Lai of 76. Compact trees produced more higher order lateral (Hol) roots than Pillar and Standard trees. More second order Lateral (Sol) roots were produced by Compact than Standard trees (1.2 vs. 0.8 Sol roots/cm first order lateral root). Pillar trees had higher shoot-to-root dry weight ratios (2.4) than Compact and Standard trees (1.7 for both) due to lower root dry weights. Root topology was similar among Compact, Pillar, and Standard peach trees but root links were significantly longer in Compact trees. The results indicate fundamental differences in root characteristics among the peach tree growth habits. Compact trees had more and longer higher order lateral roots in roots originating near the root collar (i.e. more fibrous roots) and this correlated with more lateral branches in the canopy. Shoot weights were the same among Pillar, Compact, and Standard trees but root weights were less in Pillar trees, resulting in greater shoot-to-root dry weight ratios. These results indicate significant differences in root as well as shoot architecture among growth habits that can affect their use as scion or rootstock varieties.