Browsing by Author "Marandu, Eliawoni Festo Thomas"

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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
(Sokoine University of Agriculture, 2002) Marandu, Eliawoni Festo Thomas
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.