The NC-140 multi-location peach physiology trial: Relationships between peach fruit weight, crop density and early season temperature

A multi-location trial was conducted to evaluate the individual and combined effects of crop density (CD) and early-season temperature on peach fruit weight (FW) at harvest. 'Redhaven' and 'Cresthaven' peach trees growing at five sites were hand-thinned each of four years to provide a range of CDs. For each site, cumulative growing degree days were calculated from minimum and maximum daily temperatures for the first 30 days after full bloom using 4°C as the base temperature (CGDD₃₀). The relationships between average FW and CD and CGDD₃₀ were fairly variable, but FW was generally negatively related to both CD and CGDD₃₀. There was a negative quadratic relationship between days from bloom to harvest and CGDD₃₀. Variability in the data likely resulted from differences in orchard practices at the different sites. The interaction of CD and CGDD₃₀ was rarely significant at an individual site, indicating that the two factors are independent and have an additive effect on FW and days from bloom to harvest.