ISHS Acta Horticulturae 557: VII International Symposium on Orchard and Plantation Systems
MODIFYING PHENOTYPIC CHARACTERS OF PEACH WITH GRAFT TRANSMISSIBLE AGENTS |
| Authors: | G.L. Reighard, D.R. Ouelette, K.H. Brock |
| Keywords: | Prunus persica, interstem, Peach Latent Mosaic Viroid, bloom delay |
| Abstract:
In the eastern United States, delaying peach tree phenology is an important cultural objective that reduces risk from spring freezes and improves cropping consistency. The most effective bloom delay practices involve application of plant hormones that are either not labeled for peach or perform inconsistently. Graft transmissible agents discovered in ‘Ta Tao’ numbered selections have reliably delayed peach bloom in South Carolina. To study the effect of these agents in conjunction with a ‘Ta Tao’ genotype that is high chilling and late blooming, an orchard of 'Redglobe' on interstems budded to certified virus-free Lovell rootstock was planted in 1995 as a randomized complete block design with 5 treatments and 8 blocks. The treatments were 'Redglobe' budded to 'Ta Tao 5' interstems (RTTI) containing the transmissible agents (i.e., infected), 'Ta Tao 5' interstems (RTTC) from heat treated budwood (i.e., clean), virus-free indexed 'Jersey Pink' (high chill, late blooming cultivar) interstems (RJPC) and 'Redglobe' on Lovell with no interstems which were either shield budded with infected 'Ta Tao 5' buds (RI) or not (i.e., control or RC). In 1997, 1998, and 1999, RTTI and RI trees significantly delayed full bloom 5-6 days and fruit maturity 3.5-9 days compared to RC trees. RTTI and RI trees were 16-18% smaller in trunk cross-sectional area (TCSA) than RC trees. Fruit yields were significantly lower in RTTI trees than all other treatments in 1997 and 1999, whereas yields of RI trees were the same as RC trees. Harvest index (kg fruit/cm2TCSA), fruit firmness and soluble solids of RTTI and RI trees were equal or significantly higher than other treatments in all 3 years. Fruit weight was significantly lower in RTTI, RI and RTTC trees in 1998 and 1999. Photosynthetic photon flux at the mid-scaffold level was significantly higher in the RTTI trees in all 3 years. The graft transmissible agents in ‘Ta Tao’ are believed to be Peach Latent Mosaic Viroid and Apple Chlorotic Leaf Spot Virus. | |
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