Considerations in breeding for improved yield and quality in arabica coffee (Coffea arabica L.)

D.J.A. Walyaro

Research output: Thesisexternal PhD, WU

Abstract

<p/>Variation for growth., yield and quality characters was studied in a diallel cross among 11 varieties of arabica coffee. The objective was to demonstrate the possible application of such information in breeding programmes for improved yield and coffee quality.<br/>Growth characters especially girth, height, internode length on stem and primaries, and canopy radius had a high repeatability. Such characters are heritable, even with a single measurement taken on young coffee trees. For most yield characters, a good assessment can only be obtained if it is based on the mean of several years' records Regarding quality characters, single berry weight, % AA, %AB and %PB showed a high heritability.<br/>Genetic variation for selected growth and yield characters was due to genes with additive and dominance effects. There was also evidence of epistatic effects among genes governing most of these characters, and especially so for yield. As a consequence many of the F <sub>1</sub> hybrids displayed considerable hybrid vigour varying between 10% to over 200% above the better parent. Variation for quality characters was chiefly due to the additive genetic effects, specific combining ability being relatively unimportant.<br/>A detailed study of genotype-environment interactions revealed that it is possible to select for high yielding genotypes with the desired level of linear response to environments. Yield stability and compact growth are characters that could be selected for independently. Quality characters in general were relatively less influenced by effects of genotype-environment interactions.<br/>Height and angle of primaries could be selected on basis of 1 year old seedlings in the nursery. It is also possible to base individual tree selection for yield on performance of fairly young coffee trees. This entails use of a preselection index comprising for instance, girth, canopy radius or internode length on primaries, bearing primaries or % bearing nodes, plus yield of the first 2-3 years of individual trees. For coffee quality, rapid improvement could be obtained by basing selection on %AA for bean size, and on the overall standard for liquor quality. The first year's assessment of these characters is already sufficient for selection purposes.<br/>Implications of these results in breeding programmes are discussed. A breeding scheme is proposed aimed at developing compact high yielding coffee varieties with good quality which also combine resistance to the two main diseases of arabica coffee, coffee berry disease and coffee rust. The breeding scheme entails either development of hybrid varieties, or a programme of further selection to derive seed varieties. Important features of such a scheme are, 1) the use of information on genetic basis of variation for certain characters in planning hybridization programmes and, 2) a drastically reduced breeding cycle per generation as a result of basing selection, within each generation, on fairly young coffee trees.<p/>
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
Supervisors/Advisors
  • Sneep, J., Promotor, External person
Award date16 Nov 1983
Place of PublicationWageningen
Publisher
Publication statusPublished - 1983

Keywords

  • coffea
  • coffee
  • plant breeding
  • productivity
  • quality
  • yields

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