Forage Quality and Yield in 4X Progeny from Interploidy Crosses in Dactylis L.

Abstract

Important goals in forage‐grass breeding are improvement in forage yield and quality. The objectives of this study were to evaluate 4x offspring from interploidy crosses of Dactylis L. and 4x‐4x crosses, one parent in each cross originating from wild germplasm. Tetraploid parental and offspring genotypes were planted at three locations in Wisconsin. Each plant was surrounded by solid‐seeded cultivated orchardgrass (Dactylis glomerata L.) to provide root and shoot competition without losing the identity of individual genotypes. Plants were harvested three times during 1987 and dry‐matter yield (DMY) determined. Each plant was analyzed for forage quality traits (in vitro dry‐matter disappearance, neutral detergent fiber, acid detergent fiber, acid detergent lignin). Statistical analysis was done for total seasonal dry‐matter yield and the weighted average of forage quality traits over harvests. Means and ranges among genotypes were generally similar for forage quality traits in parents and offspring. The performance of offspring for DMY was inferior to the parents. Significant (P ≤ 0.05) genotypic effects were detected for parents as well as offspring. Genotype ✕ location interaction was significant (P ≤ 0.05) for all traits but one in each generation. There was variation for more traits among 2x‐4x families than for other family groups. Within‐family variation for forage quality traits was not consistent. For DMY, all but one 4x‐2x family had significant (P ≤ 0.10) within‐family variation, whereas no 2x–4x family showed this variation. The performance of offspring families appears to be more related to the cultivated 4x parent than to the parent from wild germplasm. There was sufficient variation in the desired direction for all traits to permit phenotypic selection of offspring genotypes exceeding the best parents.