ENVIRONMENTAL CHALLENGES OF BREEDING PEACHES FOR LOW CHILL REGIONS

Abstract

Peach production throughout the world suffers from a multitude of environmental challenges related to both temperature and humidity but it is mainly the stress caused by excessive warmth that makes the low chill regions (<500 chill hour accumulation) of the world unique from those of the high chill production zones. These mild winter environments range from the cool highland mountains of Mexico where peaches can be induced to flower in the summer months so the fruit is harvested in the off season winter months, to hot dry deserts where flower induction is needed to synchronize bloom in the absence of a distinct cool season, to the humid and cool spring lowland environment of southern Brazil, to the humid but warm spring lowland environment of south and central Texas, and to the greenhouse environment of peach protected culture in Asia. The major abiotic environmental challenges are for adaptation to low chilling accumulation, cold damage during bloom, and in many cases also to high heat especially during bloom time but also during subsequent growth of the fruit and the tree. These factors affect productivity as well as fruit ripening time, size and quality.