Genotypic diversity of Coffea canephora cv. Conilon identified through leaf morpho- and eco-physiological traits

The knowledge about the genetic variability of a population is essential to increase the selection efficiency of promising genotypes to breeding programs. This study evaluated the genetic diversity among nine Coffea canephora genotypes based on leaf morphophysiological traits, e.g., dry mass (DM), leaf mass per unit area (LMA) and the relative water content (RWC%), as well as the performance of the photosynthetic apparatus, through PSII functioning and electron transport, performed in summer and winter in three periods of the day. Three distinct groups were formed based on chlorophyll a fluorescence (ChlaF) parameters, demonstrating the heterogeneity of the genetic constitution of the evaluated population, what is quite relevant for the analysis of genetic divergence and breeding purposes, having the potential to identify superior genotypes. In summer and winter, the initial fluorescence (F0) tended to increase in the morning and noon, while the quantum yield of the primary photo-chemistry (phi P0) increased in the afternoon. Leaf traits increased in the summer period in all groups. Group 1 showed more significant dissimilarity when compared to the others, with a higher mean of the most variable fluorescence parameters and a lower mean of the design index. The multivariate analyses showed that the leaf traits are correlated with the OJIP-test parameters concerning the variability in the periods and times studied. Our findings showed that the leaf traits can be adequately used to study genetic diversity in coffee. Additionally, ChlaF revealed to some extent some physiological differences among coffee genotypes associated with the two annual periods studied.