Genetic gain on grain yield, agronomic traits and malting quality of selected barley cultivars in the Western Cape Province, South Africa

Abstract

This study evaluates the genetic gain in nine barley cultivars released from 2004 to 2020, focusing on agronomic and malting quality traits. Field experiments were conducted in two locations during the 2023 growing season, Caledon and Heidelberg, representing different rainfall conditions. Caledon, a high rainfall area, had the highest grain yield, with Malgas (S20) emerging as the top performer with a yield of 6.17 t ha-1 and 4.50 t ha-1 in Heidelberg a low rainfall area. Genetic improvements in ear m-2 were observed in Bitou (S19), which produced 516 ears m-2 despite a lower plant density of 8 plants m-1 compared to older cultivars like Nemesia (S04), which produced 416 ears m-2 with a density of 9 plants m-1. Recent cultivars bred at SABBI including Kadie (S16) and Malgas (S20) displayed shorter plant heights at 63 cm compared to older cultivars, Disa (S06) and Agulhas (S09) reaching heights of 73 cm and 75 cm, indicating the incorporation of dwarfism trait. Contrasting trends in total nitrogen content were observed between the locations, with Caledon showing a positive relationship with years of release (y = 0.0088x - 16.167), while Heidelberg exhibited a negative relationship (y = -0.0045x + 10.872). Plumpness consistently improved over time, with Bitou (S19) showing the highest plumpness in both locations (Caledon: 95.82%, Heidelberg: 96.97%). However, significant differences and negative relationships were observed in screenings in both locations (Caledon: y = -0.192x + 390.1, p<0.045; Heidelberg: y = -0.0594x + 120.62, p<0.041). This study highlights the importance of barley breeding and genetic gain on grain yield and malting quality. Continued breeding efforts are crucial for enhancing barley production in diverse climatic conditions.