Evaluation of Chickpea (Cicer Arietinum L.) Genotypes for Host Plant Resistance to Ascochyta Blight (Ascochyta Rabiei) in Elgeyo-Marakwet, Uasin-Gishu and Baringo Counties of Kenya
Chemweno, Jacob Kiprop
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In Kenya, the counties of Elgeyo-Marakwet, Uasin-Gishu and Baringo, where maize, wheat and barley are normally grown, can be used to produce a second crop during the off-season (October-February) before the next cropping season or as a rotation crop during the main season (April-August). Introduction of drought tolerant leguminous crops such as chickpea in these counties is ideal in order to provide an alternative source of income to farmers. However Ascochyta blight (AB) disease which causes a lot of yield loss in chickpea could hinder this effort. Although the disease can be controlled by application of fungicides, host plant resistance is the most ideal as it is cheaper and ecologically sustainable. The objectives of this study were; to determine Ascochyta blight disease incidence and severity levels among selected chickpea genotypes in Elgeyo-Marakwet, Uasin-Gishu and Baringo counties, to determine the effect of Ascochyta blight disease on grain yields of selected chickpea genotypes in the three counties and to determine resistance levels to Ascochyta blight disease among selected chickpea genotypes. The study was carried out in three field sites; at Eldoret (LH4) in Uasin-Gishu county, Kaptagat (UH4) in Elgeyo-Marakwet county and ATC-Koibatek (UM4) in Baringo county. Greenhouse screening was carried out at Egerton University. Twenty five genotypes were obtained from Egerton University’s Seed Unit for evaluation in the three field sites and in the greenhouse. In the field, each genotype was sown in 2 m × 2 m plots, while in the greenhouse the genotypes were sown in 2 kg plastic containers. Each experiment was replicated 3 times in a randomized complete block design (RCBD). Data on disease incidence, severity and resistance levels to Ascochyta blight disease was obtained. Also data on grain yield and yield loss due to Ascochyta blight disease together with yield components such as plant height, number of pods, hundred seed weight, biomass and days to physiological maturity were collected. Collected data was subjected to Analysis of Variance (ANOVA) using PROC GLM of the SAS software. Correlation analysis was done using the PROC CORR procedures of the SAS (Version 9.3) and means were separated using Duncan’s Multiple Range Test (DMRT) at α = 0.05. There was very high (> 85 %) Ascochyta blight disease incidence in the three field experimental sites. Analysis of variance showed significant difference (P ≤ 0.0001) in resistance levels among the test genotypes; with mean resistance level of 5.68, coefficient of variation C.V = 12.55 and R2 = 0.88. There was a negative correlation (r = -0.84) between resistance levels of the test genotypes and their grain yield performance. Yield performance had a positive correlation with yield parameters such as number of pods (r = 0.85), biomass (r = 0.51) and hundred seed weight (r = 0.39), and a negative correlation with plant height (r = -0.09). Genotypes ICCV92318, ICCV07308, ICCV07304, ICCV00302 and ICCV6571 found to be both high yielding and moderately resistant to Ascochyta blight disease, are recommended for adoption in the three counties. Genotype ICCV05315 which was moderately resistant but low yielding is recommended for further breeding aimed at improving its yield. Similarly genotypes ICCV 96329, ICCV92944 and ICCV93954 which were high yielding but more susceptible to Ascochyta blight disease are recommended for further breeding aimed at improving their resistance.