Evaluation of cassava genotypes and induction of flowering for the management of cassava mosaic and brown streak diseases

Obare, I.J.

Evaluation of cassava genotypes and induction of flowering for the management of cassava mosaic and brown streak diseases

Autores

Obare, I.J.

Editor

Egerton University

Descripción

Cassava a food security crop in Kenya, particularly in western Kenya. Its production is constrained by cassava mosaic disease (CMD) and cassava brown streak disease (CBSD), both of which cause yield losses. The objectives of this study were to: i) to evaluate the genetic diversity and determine disease incidences of CBSD and CMD on cassava genotypes in Western Kenya, ii) to evaluate farmers’ knowledge on cassava genotypes in western Kenya, iii) to evaluate the resistance of elite cassava genotypes to CBSD and CMD, and determine their agronomic performance in Western Kenya and iv) to evaluate plant growth regulators, pruning and extended photoperiodism in the induction of flowering in cassava. Surveys were conducted and samples of genotypes collected in five counties for the first and second objectives. Collected samples were genotyped using DArTSeq and indexed for viruses. Results revealed incidences of CMD (60.5%) and CBSD (22.7%), with dual infections in Busia, Homabay, and Migori, while genotyping revealed a low genetic diversity. Farmers’ knowledge was analyzed using a bivariate probit model. The landraces remained dominant as compared to improved varieties at 54%. Storability (β = 1.346, p < 0.01), pest and disease resistance (β = 0.404, p < 0.05), and market demand (β = 0.577, p < 0.05) positively influenced landrace preference. To identify superior genotypes, evaluation trial was laid in Kakamega and Busia using randomized complete block design. Agronomic parameters, along with disease incidence and severity, were collected and analysed by analysis of variance (ANOVA), additive main and multiplicative interaction ANOVA and genotype stability index. Results revealed significant genotype, environment, and genotype by environment interactions (p ≤ 0.001) affecting disease resistance and agronomic traits, with Nase 14, Pwani, MM96/3567, and Mkumba emerging as stable and had dual-resistance. Breeding progress was further advanced through flowering induction experiments at KALRO Thika. Data were collected based on flowering parameters and analysed by ANOVA. Flower induction techniques utilised significantly enhanced female flowers (p < 0.001) in the test clones. Collectively, these studies demonstrate that cassava production in western Kenya is constrained by disease incidence, low genetic diversity, and farmer reluctance to adopt improved varieties, but highlight the potential of dual-resistant elite genotypes and flowering induction techniques to accelerate breeding. It is recommended that breeding programs prioritize deployment of resistant cultivars, integrate farmer-preferred traits, strengthen germplasm conservation, adopt flowering induction methods, to ensure sustainable cassava production for food security.