Genetic Progress for Yield and Yield Components and Reaction to bean Anthracnose (Colletotrichum lindemuthianum) of Large-Seeded Food Type Common Bean (Phaseolus vulgaris) Varieties in West Shoa Zone, Ethiopia
Fourteen common bean (Phaseolus vlgaris L.) varieties that were released in Ethiopia from 1997 to 2012 as large-seeded food type common bean varieties were evaluated with the specific objectives to: (1) estimate the genetic progress made in 15 years of common bean breeding in Ethiopia; (2) assess changes in associated traits in the genetic improvement of common bean varieties released in Ethiopia; and (3) assess the reaction of common bean varieties to bean anthracnose [Clletotrichum lindemuthianum (Sacc. and Magnus) Briosi and Cavara]. The study was conducted at two locations, Bako and Gute during 2014/2015 main cropping season in a randomized complete block design (RCBD) with three replications. Days to 50% flowering (DF), Days to 90% maturity (DM), Grain filling period (GFP), Hundred Seed weight (HSW), Biomass yield (BMY), Grain yield per plot (GY), Harvest index (HI), Biomass production rate (kg/ha/day), Seed growth rate (kg/ha/day), Grain yield per day (kg/ha/day) and Anthracnose (1-9) scale data were collected on plot basis and Plant height, Number of pods per plant, Number of seeds per pod, Number of seeds per plant and grain yield per plant data’s were collected on plant basis. Statistical data analyses were performed for biomass yield, grain yield, seed weight, harvest index and bean anthracnose severity. Combined analysis of variance showed highly significant differences among the common bean varieties and between test environments for hundred seed weight. The VXL interaction of seed weight did not show significant difference among the varieties. Regression analysis of mean performance at both environments on year of varietal release showed positive relationship for seed weight (r = 0.08), biomass yield (r = 0.04) and anthracnose disease severity (r = 0.10) but negative relationship for grain yield (r = -0.38), and harvest index (r = -0.37). The highest overall locations mean average of grain yield was 2679.5 kg ha-1 for Ayenew and the lowest was 1050.2 kg ha-1 for GLP-2, the grand mean being 1806 kg ha-1. The annual rates of genetic progresses were 12.7 kg ha-1 (0.13% ha-1 year-1), -48 kg ha-1 (-0.39%), 0.68 g 100 seed-1 year-1 (0.34% 100 seed-1 year-1), -0.004% and 0.39% for biomass yield, grain yield, seed weight, harvest index and anthracnose disease severity, respectively. Generally, the grain yield was reduced in the period of genetic improvement, due to the consistent performance of the reference variety Gofta. Stepwise regression indicated that grain yield day-1 (82.5%) and days to mature (21.8%) explained more for the variation of grain yield; but, seed size (-40.2%) was more important cause for grain yield reduction than bean anthracnose (-9.3%). It could, thus, be concluded that the yield of large seeded food type common bean varieties were reduced due to anthracnose and its large seeded for the last fifteen years (1997- 2012) of breeding; in future also managing the disease; especially, anthracnose disease will be crucial and Ayenew (26.79.5 kg ha-1), Gofta 2627.1 kg ha-1) and Fedis (2180.6 kg ha-1) are recommended for production in the study areas.