Seasonal pattern of root growth in relation to shoot phenology and soil temperature in sweet cherry trees (Prunus avium): A preliminary study in central Chile
The period between flowering and harvest in the sweet cherry (Prunus avium L.) is shorter than most fruit trees; thus, competition for assimilate and nutrients occurs early in the season. To properly supply water and nutrients during this critical period, optimal growth and root development are necessary. To characterize the root growth pattern of cherry trees in relation to shoot growth and phenology, a study was conducted on a 'Bing' cherry orchard on Gisela 6 rootstock at fourth leaf, located in central Chile (34°70' S, 70°43' W). During the 2009-2010 season, the shoot length and fruit diameter were measured on eight trees, and the root length was quantified by installing rhizotrons on two trees. Additionally, a two-tone (black/white) plastic cover was placed in the row over one tree with a rhizotron to analyze the effects of the plastic cover on soil temperature and root growth. The results showed three peaks of root growth during the season. The first peak occurred 43 days after full bloom (DAFB), corresponding to the phenological stages of the fruit turning from green to straw color. This peak occurred at 326 accumulated degree days (ADD) in the soil and 212 ADD in the air. The second peak was observed after harvest at 97 DAFB, when the shoot growth had stopped, and the soil and air had accumulated 932 and 692 degree days, respectively. The third and last peak occurred at 167 DAFB, with 1887 ADD in the soil and 1361 ADD in the air. The plastic cover increased the average soil temperature by approximately 1 °C, thereby increasing the ADD by 105.2 units during the study period. However, this increase was not enough to affect the root growth pattern.