Genipa americana (Rubiaceae) is a fruit tree with broad phytogeographic domain and suitable for different silvicultural systems in the tropics. The knowledge associated with the relative growth rate of species such as G. americana, provides important guidelines for the effective establishment and survival of seedlings after planting in the field. In this study we investigated differences in growth, biomass allocation and photosynthesis of seedlings originating from different mother plants of G. americana in southern Bahia, Brazil. For this, we evaluated fifteen variables associated with carbon balance at the whole plant and leaf scales of twelve G. americana progenies. All seedlings grew over a period of 198 days under similar microclimatic conditions with approximately 65% full sun. Our results showed significant differences in the relative growth rates (RGR), with the highest and lowest mean values being 29.0 and 38.0 mg g^-1 day^-1, respectively. Differences in RGR between G. americana progenies were highly related to differences in biomass allocation at both whole plant and leaf scales. From a practical point of view, we demonstrate that the selection of mother plants to produce seedlings with higher growth rates, and consequently greater establishment capacity in field plantings, can be made from evaluations of growth and biomass allocation variables at the whole plant scale.

Damage to the photosynthetic apparatus during leaf dehydration is an indicator of the maintenance of leaf vitality and the resilience of tree seedlings to severe drought. Genipa americana is a tree widely distributed in the neotropical region but with great ecological and sociocultural importance in the south of the state of Bahia, Brazil, where its fruits are harvested from subspontaneous trees. This study aimed to compare the feasibility of the maximum quantum efficiency of photosystem II (Fv/Fm) and performance indexes derived from the JIP test, i.e., performance index on absorption basis (PI_abs) and total performance index (PI_total), for screening G. americana seedlings from different mother plants for leaf damage caused by dehydration. From leaf dehydration curves, we calculated the values of relative water content (RWC) in which Fv/Fm, PI_abs, and PI_total reach a loss of 10% and 50% in relation to the values of fully hydrated leaves. PI_total was the only parameter that revealed consistent significant differences between progenies for RWC at 50% of percentage loss. Significant differences were observed among progenies for leaf traits; however, no correlation was detected between these traits and chlorophyll fluorescence parameters. Monitoring the PI_total values during leaf dehydration is a useful tool for screening G. americana progenies in relation to their capacity to maintain leaf vitality under occasional severe droughts.