Studies on x genotype interrelationships environment yield growth, among interaction and quality and components of robusta coffee {coffea canephora pierre ex froehner)clones in Kagera region
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Date
2002
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Sokoine University of Agriculture
Abstract
In March 1998, on-farm robusta coffee trials were established in farmers' fields and
three farmers in each villages of Chanika, Bisheshe, Kabirizi A and Kabirizi B were
selected in Kagera region, Tanzania. The aim of the study was to evaluate the response,
stability and to determine the association between variables of selected robusta clones in
order to give recommendations specific for the different agro-ecological zones in Kagera
region. Each farmer planted 8 genotypes and for each genotype, five trees were planted
making a total of 40 trees per farmer/replicate. Planting was done at a spacing of 3m x
2m in a randomised complete block design with three replicates in each location. Data
collection was earned out on already established robusta coffee plants. Collected data
were subjected to ANOVA, covariance, correlations, stability and path coefficient
analyses. From the ANOVA across four locations; plant height, plant girth, canopy
radius, number of primary branches, percentage bearing primary branches, yield of clean
coffee and coffee leaf rust indicated significant location variations. Percentage bearing
primary branches and coffee leaf rust indicated significant genotype x location
interactions. Two years yield depicted significant variations for location x year
interactions and location differences. Kabirizi A and Kabirizi B showed better
performance on yield and its components as compared to Bisheshe and Chanika. Two
locations ANOVA viz: Kabirizi A and Kabirizi B indicated significant location
variations fbr CBB while percentage screen 16,14 and 13 indicated genotypic variations.
MS1/95, MS2/95 and MS3/95 had higher percentage screen 16 an indication of large
bean size. Results from correlation and path coefficient analyses revealed that plant
height and number of berries per node are important variables which directly influence
yield with high positive correlations with yield. For quality variables, percentage screen
16 and percentage screen 14 are important variables which directly influence yield. Plant
girth, canopy radius and number of primary branches interacted positively with plant
height in their contribution to yield. Clean coffee in 1kg cherries and 100 seed weight
also interacted positively with percentage screen 16 in their contribution to yield. Results
from expected genetic advance and heritability across the four locations revealed that
plant girth, number of berries per node and fruit set percentage had high heritability
estimates and good expected genetic advance hence selection for these variables may
start from the early generations of robusta coffee improvement programme. Stability
analyses used revealed that, MS5/95 was stable for plant height, number of flowers per
node and fruit set percentage while FS was stable for plant height with desired stature.
MS6/95 was stable for percentage bearing primary branches. For yield, MS 1/95,
MS2/95, MS3/95 and MS5/95 if intercrossed have potential to give segregants with
stable and high yield. Therefore, the stable genotypes for particular traits should be used
as source of stability genes for breeding work in robusta coffee.
Description
Dissertation
Keywords
X genotype, Environment yield growth, Robusta coffee quality, Coffee canephora pierre ex froehner, Kagera region