WHY DO EARLY HIGH SPRING TEMPERATURES REDUCE PEACH FRUIT SIZE AND YIELD AT HARVEST?

High temperature stress is often considered to involve situations when temperatures are above the typical optima for plant assimilatory functions but higher than normal temperatures at specific times can also negatively influence source-sink relations to the detriment of fruit growth and yields.
Previous research has documented that years with above-normal early spring temperatures (within 30 days after bloom) correspond to years with early fruit harvest and below-average fruit sizes.
This has been a particular problem for California peach growers because the market is increasingly intolerant of small fruit.
Our research indicates that fruit development and growth potential of a given cultivar is governed by a relative growth rate function which is driven by both time and temperature.
However it is clear that fruit development and growth potential do not always equate to actual fruit growth.
Furthermore, fruit growth potential that is not realized within a given time interval is lost and cannot be made up.
In this paper we will show how higher than normal temperatures within 30 days of full bloom can result in increased fruit growth potential per day but decreased actual fruit growth over the fruit development period.
This represents a form of heat stress that would not be typically considered as heat stress because the temperatures involved are not above temperature optima for assimilatory processes but can have important practical consequences for fruit size and yield.

IX International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems

G. Lopez, K.R. Day, T.M. DeJong

Prunus persica, carbohydrate partitioning, fruit development, fruit growth, fruit size

https://doi.org/10.17660/ActaHortic.2011.903.147