Selection for Apparent Photosynthesis and Related Leaf Traits in Early Generations of Soybeans¹

Abstract

Evidence suggests that photosynthate production may be yield‐limiting in soybeans [Glycine max (L.) Merr.]. This study was designed to estimate potential for selection of CO2‐exchange rate (CER), specific leaf weight (SLW), leaf thickness (LT), and leaf density (LD) in early generations of soybeans.Two crosses (‘Amsoy’ ✕ ‘Ford;’ ‘Corsoy’ ✕ ‘Hawkeye’) involving adapted cultivars high (Amsoy, Corsoy) and low in leaf CER were used. CER, SLW, LT, and LD were measured in parents, F1s and F2s. CER was measured in selected F3 and F4 lines of one cross, whereas the other variables were measured in all F3 and F4 lines.All traits showed quantitative inheritance without dominance effects. Broad‐sense heritability, based on parental, F1 and F2 variances, was low to moderate for CER (0.36, 0.56); it was low to very low for the other variables. Selection for either high or low CER in the F2 or F3 was ineffective. Gain from hypothetical selection for SLW was about 596 in the F2 and 5‐11% in the F2. Gain from hypothetical F3 selection in LT was about 5%. LD showed poor gain.Use of pure lines from advanced generations may give an entirely different picture of the potential for direct selection for increased photosynthesis than that shown by this study.

Use of the QTL approach to the study of soybean trait relationships in two populations of recombinant inbred lines at the F7 and F8 generations

“…On the other hand, Wiebold et al (1981) observed a low to moderate (36% to 56%) heritability in the broad sense, for net photosynthesis of individual leaves, in the initial F 3 and F 4 generations using an infrared gas analysis system at temperatures varying from 29 to 31 o C. Table 1 shows heritability values for W ST , n N e W N of 87.47%, 18.70% e 32.02%, respectively. These values are in agreement with the observations of Santos et al (2006) who estimated heritability values of 49% for stem dry mass, 30% for nodule number, and 33% for nodule dry mass, in a segregating population composed of 157 recombinant inbred lines derived from the cross between two soybean cultivars identified as contrasting for biological nitrogen fixation capacity.…”

Morphological analysis and photosynthetic performance of improved papaya genotypes

“…The existence of inter and intra genetic variability in photosynthetic rate was discussed for a wide number of crop species, namely soybean (Wiebold et al, 1981), corn (Heichel and Musgrave, 1969), pea (Mahon and Hobbs, 1981), strawberry (Hancock et al, 1989), chickpea (Anilkumar et al, 1993), wheat (Watanabe et al, 1997), bean (Gonzáles et al, 1995) and cotton (Pettigrew and Turley, 1998). However, whether this variability can be used to improve crop production is not conclusive (Joshi, 1997).…”

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

“…However, other research has not demonstrated positive results. 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.…”