Cool Orchard Temperatures or Growing Trees in Containers Can Inhibit Leaf Gas Exchange of Avocado and Mango

Abstract

Leaf gas exchange of avocado ( Persea americana Mill.) and mango ( Mangifera indica L.) trees in containers and in an orchard (field-grown trees) was measured over a range of photosynthetic photon fluxes (PPF) and ambient CO 2 concentrations ( C a ). Net CO 2 assimilation ( A ) and intercellular partial pressure of CO 2 ( Ci ) were determined for all trees in early autumn (noncold-stressed leaves) when minimum daily temperatures were ≥14 °C, and for field-grown trees in winter (cold-stressed leaves) when minimum daily temperatures were ≤10 °C. Cold-stressed trees of both species had lower maximum CO 2 assimilation rates ( A max ), light saturation points ( Q A ), CO 2 saturation points ( C aSAT ) and quantum yields than leaves of noncold-stressed, field-grown trees. The ratio of variable to maximum fluorescence ( F v /F m ) was ≈50% lower for leaves of cold-stressed, field-grown trees than for leaves of nonstressed, field-grown trees, indicating chill-induced photoinhibition of leaves had occurred in winter. The data indicate that chill-induced photoinhibition of A and/or sink limitations caused by root restriction in container-grown trees can limit carbon assimilation in avocado and mango trees.