Agronomic Changes from 58 Years of Genetic Improvement of Short‐Season Soybean Cultivars in Canada

Abstract

breeding in short-season regions resulted in a yield improvement of 0.5% per year with an associated decrease Yield progress of short-season soybean [Glycine max (L.) Merr.] in protein concentration and some improvement in lodgcultivars in Canada has been approximately 0.5% per year since the early 1930s. Our objective was to identify changes in agronomic traits ing tolerance. In a related experiment, we grew 14 cultiassociated with yield increase within a selection of historical cultivars.vars selected from the original 41 to examine physiologi-Where applicable, we measured phenotypic stability of these traits.cal changes from 58 yr of genetic improvement (Mor-At Ottawa, ON, we grew 14 cultivars, representing seven decades of rison et al., 1999). We found that increased seed yield breeding and selection , in a randomized complete block was significantly correlated with decreased leaf area and design with four replicates, across 6 yr. Data were collected on seed increased photosynthetic and stomatal conductance yield, seed weight, plant height, plant population, lodging susceptibilrates per unit leaf area. ity, and foliar disease symptoms. Seed number per plant was calculatedOur objective in the current study was to examine from yield, seed weight, and plant population. Seed protein and oil the changes in agronomic traits associated with 58 yr of concentration were measured. The increase in seed yield with year soybean breeding in short-season cultivars. Specifically, of release was associated with a significant increase in the number of seeds produced per plant. There was no relationship between seed we examined plant height, lodging score, foliar damage yield and seed weight. A significant decrease in seed protein concen-score, plant stand, seed weight, seeds per plant, seed tration with year of release was offset by a significant increase in seed yield, and protein and oil concentration. We determined oil concentration. Newer cultivars were more phenotypically stable the phenotypic stability of these agronomic traits.for plant height than older cultivars. Modern cultivars were more efficient at establishing, supporting, and filling seeds on a per-plant MATERIALS AND METHODS basis than older cultivars.Abbreviations: CV, coefficient of variability; MG, maturity group.

Effect of reduced tillage on quality traits of soybean [ Glycine max (L.) Merr.]

“…The results were in accordance with those of many authors who emphasized the importance of the climate conditions during the growing season in the development of the grain yield (Morrison et al, 2000;Košutić et al, 2001;Wilhelm and Wortmann 2004).…”

“…The changes may be detrimental, neutral or beneficial for crop growth and yield, depending on the soil texture and structure (Dick and VanDoren, 1985) and on 84 climatic factors such as rainfall (Morrison et al, 2000). According to Wilhelm and Wortmann (2004) the soybean grain yield was less responsive to favourable environments after soil loosening with a chisel plough than in other tillage treatments.…”

Soybean Yield Formation: What Controls It and How It Can Be Improved

“…In contrast, Dornhoff and Shibles (1970) compared 20 cultivars released across time and demonstrated a general trend between CER and yield, although exceptions occurred. More recent studies by Morrison et al (2000) with new and old Canadian cultivars did report a 0.52 % per yr increase in the photosynthetic rate, a level very similar to the annual yield increase shown by these cultivars. However, an inverse relation of photosynthetic rate per leaf with LAI may have negated some of the positive effect of increased photosynthetic rate.…”

The Quality of Sunflower Seed Oil Changes in Response to Nitrogen Fertilizer

“…The reduction in oil content of sunflower seeds maybe was due to a dilution effect. In oil crops, an increase in oil concentration is generally associated with a decrease in protein concentration (López Pereira et al, 2000;Morrison et al, 2000;Uribelarrea et al, 2004). Grain oil accumulation greatly depends on the C economy of the crop during the post-flowering, grain-filling period.…”