Growth, Yield, and Yield Component Changes among Old and New Soybean Cultivars

Abstract

Soybean [Glycine max (L.) Merr.] yield has increased at a rate of 25 to 30 kg ha -1 yr -1 due in part to improved genetic gain, and has been further advanced by the addition of resistance to soybean cyst nematode (Heterodera glycines Ichinohe; SCN) in new cultivars. Th e objective was to determine specifi c growth changes that explain the yield improvement from old to new cultivars and the further yield improvement gained from the addition of SCN resistance. Studies were conducted at three Iowa locations during 2005 and 2006. Two old and two new SCN-susceptible, and two new SCN-resistant cultivars were evaluated for total dry matter (TDM) accumulation and leaf area index (LAI) through the season along with yield and yield components at harvest. New cultivars produced yields superior to older cultivars due to increased crop growth rate (CGR) culminating in greater TDM 105 days aft er emergence (DAE). Yield was strongly associated with the number of seeds produced m -2 and this yield component accounted for almost all of the yield diff erences among cultivars. Seeds m -2 was positively related to CGR between 42 and 105 (growth stage R1-R5.5) DAE and to LAI 105 DAE. New SCN-resistant cultivars produced yields 17 to 19% greater than new susceptible cultivars across three locations. Increased TDM and CGR explained the yield response at the low-yield location, but not at the high-yield locations. Apparent harvest index (HI) was similar among all cultivars at each location. Selection for increased yield has indirectly selected for increased TDM and CGR with a similar amount partitioned to seed dry weight. Future yield gains will be made by (i) increasing the amount and the rate of dry matter (DM) and (ii) through the increased production and duration of leaf area.

Effects of genotype on yield and yield component of soybean (Glycine max (L) Merrill)

“…The result in Table 3 show that the effects of genotypes on yield and yield component was significant (P < 0.05) confirming the previous studies (De Bruin and Pedersen, 2009;Liu et al, 2005;Norsworthy and Shipe, 2005).…”

Potential Yield of Soybean Lines Are Higher Than Their Parent Indonesian Lowland Popular Variety

“…Indeed the soil type of Ngale is Vertisol, able to retain more water than soil type of Jambegede (Entisol-Inceptisol association). On the other hand, the average grain yield obtained in this experiment was higher than these in analogical studies in tropical areas (Aremu et al, 2006), but lower than in subtropical areas (De Bruin & Pedersen, 2009;Pedersen & Lauer, 2004;Wilhelm & Wortmann, 2004). Values followed by the same letter were not significantly different at Least Significant Different (LSD) 5%.…”

Grain Yield Differences of Soybean Cultivars Due to Solar Radiation Interception

“…These losses occur in function of the interaction with the environment and the competition between the plant organs by photoassimilates during the crop cycle [31]. Post-flowering stages are considered critical for grain yielding [32] since the availability of photoassimilates throughout this period affects crop productivity [33] [34]. In addition, other factors are involved in the abscission of reproductive structures in soybean cultivars, some of them are nutrients and endogenous concentration of some plant hormones [35].…”