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Agronomy Journal Abstract -

Distribution Pattern of Yield Components in ‘Braxton’ Soybeans1


This article in AJ

  1. Vol. 76 No. 3, p. 493-497
    Received: Feb 14, 1983

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  1. E. L. Ramseur,
  2. S. U. Wallace and
  3. V. L. Quisenberry2



Nodal and other distribution patterns of seed yield and yield components are useful in modeling soybean [Glycine max (L.) Merr.] growth, in analyzing the factors responsible for yield differences between experimental treatments, and in predicting yield. The purpose of this study was to determine the influence of irrigation and intrarow spacing on the distribution of yield and yield components in a determinate soybean cultivar. ‘Braxton’ soybeans were grown in 0.91 m rows on a Cecil sandy loam soil (clayey, kaolinitic, thermic Typic Hapludults) at intrarow spacings of 43, 61, 102, and 305 mm between plants and under three irrigation treatments: full-season irrigation (FSI), irrigation beginning at bloom (BI), and no irrigation (NI). At maturity, samples were collected to determine pod number, seeds per pod, seed number, yield, and single seed weight for the main stem positions at each node and for the branches originating at each node. Branches contributed more pods, seeds, and yield than did main stems in all treatments, while seeds per pod and single seed weight were similar on stems and branches. Increases in intrarow spacing increased seed number and yield on branches and decreased pod number, seed number, and yield on the stems. Irrigation had little influence on the branch/stem ratios of yield components. Full-season irrigation and BI had greater numbers of pods, numbers of seeds, yield, and seeds per pod on stems and branches and greater single seed weight on stems than did NI. With the exception of stem seeds per pod which was greater for BI, there were no differences between the two irrigated treatments. Seed number, pod number, and yield were maximized in the lower half of the nodes whereas seeds per pod and single seed weight were greatest in the upper nodes. The upper six nodes contributed the least to yield in all treatments. Increases in intrarow spacing increased the contribution of the lower nodes to yield whereas irrigation decreased the relative contribution of the lowest nodal division. We concluded that the large contribution of lower nodes to yield was due to the large proportion of yield borne on branches produced from lower nodes. Increases in spacing resulted in greater contribution to yield of these large branches and thus to a greater concentration of yield at lower nodes. Irrigation influenced distribution of yield through influences on distribution of all yield components.

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