Physiological Growth Response in Seedlings of Arabica Coffee Genotypes Under Contrasting Nursery Microenvironments

Abstract

See, stats, and : https : / / www. researchgate. net / publication / 287198684 Physiological RESEARCH DOI : 10 . 13140 / RG . 2 . 1 . 2581 . 2568 READS 8 1 : Taye Ethiopian 18 SEE All - text , letting . Available : Taye Retrieved : 27 Plant 2015 ; 3 (5) : 47 - 56 Abstract : Arabica coffee genetic resources and shade - grown coffee landscapes are under threat largely due to human activities and lack of scientific information and understanding on adaptation mechanisms along environmental gradients . The study aims to describe the variability in early physiological growth responses in arabica coffee genotypes of varying geographical areas in Ethiopia , its birthplace . The experiment was carried out under contrasting nursery microclimatic settings at the Jimma Agricultural Research Center in Ethiopia . A split - plot design with three replications of two sunlight regimes and twelve - coffee genotypes were arranged as main and sub - plot treatments , respectively . One - year - old coffee seedlings were used to measure shoot and root growth parts and calculate derivatives on physiological parameters . The results depicted that coffee nursery shade gradients had highly significant influence on leaf mass ratio (LMR) with higher value measured in shaded seedlings . In contrast , seedlings under full - sunlight produced significantly higher shoot mass ratio (SMR) . Likewise , LMR was highly significantly different due to natural sunlight regimes , genotypes and interaction effects . Seedlings exposed to direct sunlight had relatively higher root mass ratio (RMR) , SMR , canopy area (CA) and leaf area index (LAI) . The results also revealed significant responses among coffee genotypes in RMR and LMR . Accessions from the drier Harenna areas exhibited the highest RMR , but least LMR . The accession from Bonga had the highest specific leaf area (SLA) and leaf area ratio (LAR) as opposed to the lowest SLA and LAR in the Yayu and Harenna populations , respectively . Unlike RMR , LARMR was linked to LMR and was low for Harenna and high for Berhane - Kontir . The results also exhibited reduced specific stem lengths for Harenna and Yayu , which had the highest and lowest LAI , respectively . The study shows considerable differences between open sun and shaded seedlings as well as among arabica coffee genotypes for most physiological growth characteristics considered . The results clearly demonstrate the need for shade microenvironments for production of high quality coffee seedlings with balanced shoot and root growth . The study also describes significantly different magnitudes and patterns of relationships between growth traits for future work . In view of the impacts of changing climate on coffee plant , the findings deliver evidence on genetic diversity within arabica coffee accessions of varying geographical areas in Ethiopia . However , further investigations , inter alia , on detail coffee evolutionary , anatomy , molecular , ecophysiological and desirable agronomic traits across seasons and locations for understanding adaptation strategies to environmental stresses and identifying suitable coffee cultivars for specific geographical areas .