|JOHNSON, SCOTT - University Of California|
|REIGHARD, GREGORY - Clemson University|
|CONEVA, ELINA - Auburn University|
|DAY, KEVIN - University Of California|
|FACHINELLO, JOSE - Cornell University - New York|
|FALLAHI, ESMAEIL - University Of Idaho|
|NEWELL, MICHAEL - University Of Maryland|
|QUELLETTE, DAVE - Clemson University|
|ROBINSON, TERENCEL - Cornell University - New York|
|WOLFE, DWIGHT - University Of Kentucky|
Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2014
Publication Date: 5/20/2015
Citation: Johnson, S., Reighard, G.L., Beckman, T.G., Coneva, E.D., Day, K.R., Fachinello, J., Fallahi, E., Newell, M.J., Quellette, D., Robinson, T., Wolfe, D. 2015. Environmental effects on fruit ripening and average fruit weight for three peach cultivars. Acta Horticulturae. 1084:62.
Interpretive Summary: Weather conditions are well known to affect harvest date, fruit growth and fruit quality. Weather factors contributing to this variability included early spring temperatures and solar radiation. In 2009, 12 locations established plantings of ‘Crimson Lady’, ‘Redhaven’ and ‘Cresthaven’ peaches on Lovell rootstock. Bloom dates, temperature and light regimes, harvest dates, fruit size and quality have been monitored each season since. This study has revealed that the fruit development period is highly correlated with average temperature for the 60 day post bloom period. Fruit size was found to correlate well (for two of the test varieties) with solar radiation received from bloom to harvest. Cooler post-bloom temperatures were associated with larger final fruit size. This information is critical in the development of a model to predict harvest date for grower use. Additionally, the understanding between post-bloom temperatures and final fruit size provides growers with an important additional tool to decide how hard to thin their trees.
Technical Abstract: Three peach cultivars, ‘Crimson Lady’ (early), ‘Redhaven’ (mid-season) and ‘Cresthaven’ (late), were planted at twelve locations within the USA in 2009. All trees were grafted on ‘Lovell’ rootstock and came from the same nursery. Five trees of each cultivar were planted at a spacing of 6m by 5m at each location. In 2012, eight locations were able to participate in the study. In order to obtain maximum fruit growth, trees were thinned to about 40-50 fruit within 30-40 days of bloom, were irrigated when needed and kept free of diseases and pests. When fruit started to soften (tree ripe), a first harvest was initiated. The second, and last, harvest occurred about one week later. Individual fruit were weighed and a composite sample per tree was used to measure percent soluble solids content (SSC) with a refractometer. Daily weather parameters of maximum and minimum temperatures, solar radiation, precipitation and average humidity were measured in close proximity to the orchard. Full bloom dates ranged from early March to early May for the different locations. Time from full bloom to harvest varied by about 30 days among locations for all three cultivars. This parameter correlated very well with average temperature (average of daily maximum and minimum) for 60 days after bloom. Correlation coefficients were -0.94, -0.96 and -0.98 for the three cultivars, respectively. Average fruit weight varied among sites from 141g to 216g for ‘Crimson Lady’, 159g to 313g for ‘Redhaven’ and 152g to 413g for ‘Cresthaven’. This parameter correlated well with average solar radiation from bloom to harvest for ‘Redhaven’ (r = 0.87) and ‘Cresthaven’ (r = 0.73), but not ‘Crimson Lady’. The relationship with ‘Cresthaven’ was significantly improved by adding in the factor of average temperature for 20 days after bloom (r2 = 0.91). Cooler temperatures were associated with larger fruit. No weather parameters correlated well with ‘Crimson Lady’ fruit weight or with SSC for any of the three cultivars. The study will continue for at least 2 more years to obtain more robust relationships.