Low Silicon and Better Pasture Feeding Quality: Uncovering Genetic Diversity in Russian Wildrye (Psathyrostachys juncea)

In this study, 72 genetically diverse accessions of Psathyrostachys juncea from a germplasm collection were evaluated for silicon content, biochemical composition and nutritional value in pasture biomass for grazing feed in Northern Kazakhstan in 2024 and 2025. High-quality biomass and low silicon are the most important traits for P. juncea pasture. In the studied germplasm collection, the average silicon content in leaves was 2.59%, ranging from 1.45% to 4.11%. All studied accessions of P. juncea were split into two clusters based on biochemical analyses. Cluster B with preferable genotypes had significantly lower silicon content, crude fibre, neutral detergent fibre and hemicellulose, but higher crude protein content compared to cluster A. The six best genotypes with close to or less than 2% silicon and with high nutritional value in pasture biomass content were selected from cluster B for hybridization and further breeding. Low silicon content in leaves was confirmed in most of the hybrids, similar to parents and significantly less than other genotypes in the germplasm collection. Strong negative heterosis values were identified in all hybrids for acid detergent fibre and lignin, showing a reduction in undesired traits for biomass pasture quality. A strong negative correlation was found between the content of crude protein and fibre (r = −0.71), whereas neutral and acid detergent fibre content had a strong positive correlation (r = 0.78). The most promising hybrids with the combined traits of low silicon accumulation and high-quality pasture biomass were selected for further breeding and production of new perspective cultivars of P. juncea for pastures with perennial forage plant species.