No abstract

Aims: The aim of this study was to determine the effect of different watering regimes on selected coffee genotypes and to evaluate drought tolerance among selected coffee genotypes. The study also aimed at determining the optimum watering interval for these genotypes under high temperature conditions. Study Design: Completely Randomized Design (CRD) with 3 replications. Place and Duration of Study: The experiment was conducted in a greenhouse at Coffee Research Station in Ruiru, Kenya between October and December 2012. Methodology: A total of 11 coffee genotypes were used in this study. These comprised of Coffea canephora (Robusta), one wild accession and nine Coffea arabica genotypes. Six months old seedlings of the test genotypes pre-germinated and transplanted in black polythene bags were obtained from the Coffee Research Station experimental nursery. The seedlings were placed on raised benches in the green house and each potted seedling represented a plot. The seedlings were watered with 0.3 liters of water per pot at six watering regimes applied as follows: watering after every 2 days, 4 days, 7days, 14

Coffee Berry Disease (CBD) is a major constraint that limits Coffea arabica production, whose resistance is governed by three genes, T, R that are dominant and recessive k in varieties Hibrido de Timor (HDT), Rume Sudan (RS) and K7 respectively. This study identified the genomic region occupied by R-gene using F 2 genotypes from varieties RS and SL28; and Single Nucleotide Polymorphic (SNP) markers obtained through Genotyping by Sequencing. Redundant markers were removed and 699 markers obtained for linkage mapping and quantitative trait loci (QTL) analysis. The Linkage map spread over 5525.39 cM across eleven coffee chromosomes (Chr). The QTL was analyzed by both Interval Mapping (IM) and Inclusive Composite Interval Mapping (ICIM) using SNP markers and CBD resistance mean scores of the F 2 genotypes and their parents. Three QTLs, qCBD 1-1 in Chr 1, qCBD 2-1 and qCBD 2-2 in Chr 2 were significantly associated with CBD resistance, detected by both IM and ICIM at LOD ≥ 2.5 (P≤0.05). Two flanking markers that were closer to the three QTLs; 100025973|F|0-59:T>C-59:T>C at a distance of 3 centi Morgans (cM) from qCBD 1-1 and 100034991|F|0-44:C>T-44:C>T, that was flanking in both qCBD 2-1 and qCBD 2-2 at 12.5 cM, whose SNPs were significant (P≤0.05), are recommended for validation and use in marker-assisted breeding.

The biennial bearing and the long productive nature of coffee makes it difficult to release coffee variety within a short time span. This study aimed at evaluating the yield performance of the Arabusta hybrids and its backcrosses developed by Coffee Research Institute of the Kenya Agricultural and Livestock Research Organization (KALRO-CRI) using the morphological traits. Nineteen coffee genotypes were evaluated at Siaya ATC and KALRO-Alupe using randomized complete block design with three replications and the morphological data for growth and yield was recorded during the year 2018. The results indicated that there was significant difference in yield among the coffee genotypes and between the sites. Yield had positive significant associations with parentage berries per node (r= 0.61), berries on the longest primary (r= 0.58) and berries per node on the longest primary(r=0.60). The genotypic coefficient of variation (GCV) values for the morphological traits varied from 6.50 to 31.01%. Broad sense heritability ranged from 0.15 to 0.61 with bean yield recording heritability of 0.31. The number of berries on the longest primary had high broad sense heritability and high genetic advance indicating the presence of additive genes that can be used in coffee improvement through selection.