Growth and Yield of Soybean Lines Selected for Divergent Leaf Photosynthetic Ability¹

Abstract

One way to enhance net photosynthate production in soybean [Glycine max (L.) Merr.] may be to breed genotypes with accelerated leaf photosynthetic rates. The objective of this experiment was to determine the effects of divergent selection for 14CO2‐uptake rate per unit leaf area, total photosynthesis (TPs), on seed yield and canopy growth. Eighteen F7‐derived lines were grown in the field. These included nine lines previously selected for rapid TPs and nine selected for slow TPs. Total photosynthesis was measured during the seed filling period in 1979 and 1980. The lines were not all at the same growth stage on a given sampling date, so the average TPs rate over the 30 d period after the beginning of seed filling was calculated. This average (MTPs) equals the estimated area under the curve describing TPs as a function of time over the 30 d period, divided by 30 d. The TPs groups differed (P<0.01) in MTPs (2.51 vs. 2.29 nmol/s cm2, averaged over three locations and 2 years). TPs groups did not differ in seed yield, crop growth rate, harvest index, or the duration of seed filling. Seed yield was not correlated with MTPs among the nine lines within either group. Crop growth rate was not consistently correlated with TPs (as measured on any single date) among lines within groups. The TPs groups had similar seed yields in 1981. We concluded that selection for rapid TPs, as measured on a single light‐saturated leaflet, may not lead to greater seed or dry matter yields in soybeans.

Selection For Flag Leaf Stomatal Frequency In Bread Wheat

“…No doubt, grain yield is the end product of several factors and there is no direct relationship between photosynthesis and yield. Selection for higher photosynthesis in maize (GROSBIE and PEARCE 1982) and in soybean (FoRDE et al 1983) did not result in higher grain yields. However, altered environments to enhance photosynthesis, increased the biomass or grain yield of wheat (FISCHER andAGUILAR 1976, THORNE andWOOD 1987).…”

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

“…In the United States, research has shown cultivar differences for photosynthetic rate in soybean (Dornhoff and Shibles, 1970) and a positive correlation between CAP and yield (Wells et al, 1982). Wiebold et al (1981) concluded that early‐generation selection for CO 2 exchange rate in soybean was ineffective, but Ford et al (1983) found differences in photosynthetic rates in 20 lines after seven generations of selection for the trait (although there was no significant effect on yield or harvest index). Ashley and Boerma (1989) found a positive correlation between CAP during seed fill and yield from F 3 –derived lines from two crosses.…”

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

“…Wiebold et al (1981) crossed two parental cultivars with contrasting high and low CER and could not find improved CER by the F 3 and F 4 generations. Ford et al (1983) found similar disappointing results. The current general consensus is that using CER as an indirect selection criterion in a breeding program has limited value (Frederick and Hesketh, 1994).…”