Agronomic Traits Improvement and Associations in Hard Red Spring Wheat Cultivars Released in North Dakota from 1968 to 2006

Abstract

Periodic evaluation of cultivars allows researchers to evaluate genetic variation and progress made in various traits. Determining genetic gain or lack can lead researchers to develop new strategies for trait improvements. A two‐year study was initiated in 2004 to examine the changes in agronomic performance of hard red spring wheat (HRSW) (Triticum aestivum L.) cultivars released by North Dakota State University (NDSU) over the past 40 years. The experiment was conducted in North Dakota at three sites in 2004 and two sites in 2005. The study included 33 HRSW genotypes laid out in a randomized complete‐block design. Cultivars developed since 1968, three advanced lines developed by NDSU, and three cultivars released by other breeding programs were included in the study. The Canadian cultivar Marquis (released in 1911) was included for comparison purposes. Linear regression of cultivar means on year of release showed an annual increase in grain yield of 1.3% yr−1, grain‐volume weight of 0.2% yr−1, and thousand‐kernel weight of 0.3% yr−1 since 1968. There were also significant gains in lodging and disease resistance. Resistance to leaf rust (Puccinia recondita Roberge ex Desmaz. f. sp. tritici) and Fusarium head blight (Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schweinitz) Petch]) was substantially improved in genotypes released since 2002 and 2000, respectively. Therefore, we can conclude from this study that no evidence of a decline has occurred in the improvement of most agronomic traits and that breeders should be able to continue improving these traits by introgressing favorable alleles.

Genotype × tillage interaction in a recurrent selection program in wheat

“…Some studies showed a significant decrease in days to heading (Guarda et al 2004;Lopes et al 2012). Our results are consistent with other publications (Underdahl et al 2008;Graybosch and Peterson 2010;Mladenov et al 2011;Mustaoea and Saulescu 2011) where increased grain yield was achieved without extending the crop-ping season (Fig. 1(I)).…”

Breeding progress in grain yield of winter wheat cultivars grown at different nitrogen levels in semiarid conditions

“…Generally, when results for all cultivars were compared, lodging was significantly higher (P < 0.05) at high N (32%) than at low N-level (18%). The estimated average decrease in lodging of 1.56% per year, was between values obtained by Underdahl et al (2008) Level of statistical significance: * P < 0.05; ** P < 0.01; and ns: not significant.…”

Effect of Advanced Cycle Breeding on Genetic Gain and Phenotypic Diversity in Barley Breeding Germplasm

“…Empirical studies of this type generally examine only a few cycles of selection (Mitchell et al, 1992;Courtois et al, 1993). Examples include wheat (Triticum aestivum L.) in North Dakota (Underdahl et al, 2008) and the Illinois long-term corn (Zea mays L.) selection experiment (Hagdorn et al, 2003;Dudley 2007). Another approach is to evaluate changes in traits among released cultivars over longer periods of time.…”