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 degrees C as the base temperature (CGDD(30)). The relationships between average FW and CD and CGDD(30) were fairly variable, but FW was generally negatively related to both CD and CGDD(30). There was a negative quadratic relationship between days from bloom to harvest and CGDD(30). Variability in the data likely resulted from differences in orchard practices at the different sites. The interaction of CD and CGDD(30) 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.