Evaluation of Barley for Field Resistance to Scald

Abstract

Sixteen barley genotypes were evaluated for their resistance to scald (caused by Rhyncosporium secalis) in a randomized complete block design with three replications for three seasons at Holetta and for one season at Adet and at Bekoji research centers. Results at Holetta showed that percent infection taken from lower, middle, and upper parts of the plant correlated negatively with yield and 1000 seed weight significantly (P=0.05). Correlation coefficients (r) were highest for disease evaluation taken from the middle leaf during most part of the season while high r values were obtained for disease evaluation taken from the lower and upper leaves at early and late stages of the crop development. However, disease assessment made on the middle leaf was adequate for evaluating barley genotypes for field resistance, measured in AUDPC (area under the disease progress curve). Barley genotypes showed marked differences in scald development. The varieties ‘Proctor’ and 'ARDU-12-8C’ had the highest AXJDPC values and were extremely susceptible. The varieties ‘IAR/H/485’, 'HB 52* and ‘HB 68’ sustained half to one-third the amount of scald recorded on the above
susceptible varieties and were rated moderately susceptible. The remaining eleven genotypes showed small AUDPC values with non-significant differences among them and were consistent in all testing seasons. These genotypes seemed to possess field resistance to scald and some of them, such as ‘HB 42’, ‘HB 99’ and ‘HB 100’, also gave high yields at Holetta. Development of scald was lower on plants flanked by three rows of oats than those not flanked. This suggests that the disease progresses independently within plots and could be accelerated due to inter-plot interference