Evaluation of Competitive Ability of Promising Barley Genotypes at Different Seeding Rates Under Rainfed Condition

Regarding the high cost and environmental pollution usage of herbicides، new approaches to identify new genotypes with high competitive ability in order to decrease the damage of weeds are required. This study was undertaken to evaluate the promising barley genotypes under weedy (weed interference; WI) and weed free (WF) conditions and to identify the effect of seeding rates in their competitive ability with the weeds. A factorial experiment based on RCBD with 4 replications was conducted for three cropping seasons (2004-2007) at Dryland Agricultural Research Sub-Institute (DARSI)، Sararood station، Kermanshah، Iran. Factors were included: genotypes (four promising barley genotypes and one check cultivar (Sararood-1)، seeding rates (350، 400 and 450 plant/m2)، and weed conditions (WI and WF). Results showed that promising line G4 (Lignee 131/3/4679/105/YEA168. 4) with grain yield production equal to 3938 kg/ha significantly was better than the check. No significant difference was observed in grain yield between promising line G1 (Roho//Alger/Ceres 362-1-1/3/Alpha/Durra) and the check، while the other promising lines were out-yielded by the check. The results indicated that no significantly differences were observed among the genotypes for the levels of seeding rate and weed conditions in first cropping season (with unfavorable growth condition)، while in two next cropping seasons (with favorable growth conditions) significant differences were observed among the genotypes based on both seeding rate and weed conditions factors. The highest grain yield productivity was found for the genotype 4 in 400seeds/m2 and under weed control condition in second cropping season. According to weed interference tolerance index (WITI)، promising lines G4 and G1 were better than the others، thus G4 and G1 due to high yield performance and high WITI can be recommended for cultivation under natural conditions (without weed control). High WITI values were observed in 450 plant/m2seeding rate. Regarding to increasing of WITI in higher seeding rates، increasing of seeding rate until 450 plant/m2 can be recommended as an approach to control of weeds for barley genotypes under rainfed condition.