Nine isolines of oats (Anen6 0ativa L.), developed on the Lang variety background by backcrossing, were tested in 18 environments in Iowa, USA. Isolines and Lang were evaluated ‘for four characteristics of grain yield mean across environments, response to improving environments, deviations from regression, and coefficient of determination. The latter two parameters estimate stability of productivity.
The isolines varied, significantly for’ plant heignt, heading date, test weight, and harvest index, but the ranges for these traits were small. Also, genotvoes differed significantly for grain yielc One isoline yielded significantly more, and four yielded significantly less, than Lang. The genotype X environment Eor this set of lines was largely due to linear responses of genotypes to different environments. I 501537, with a nonsignificait b-value and deviation from regression, would be superior for yield in both high-and low-productivity environments, and P1 501535, with the lowest b-value and a small deviation from regression, was the most stable isoline. Linkage between the genes for resistance to different races of the pathogene and those for expression in yield and agronomi’c traits in the oat isolines, seems to be the primary cause. of deviations observed.
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