Anatomical Characteristics of Three Inbred Lines and Two Maize Synthetics Recurrently selected for High and Low Stalk Crushing Strength
- W. A. Berzonsky,
- J. A. Hawk and
- T. D. Pizzolato
Despite progress in improving maize (Zea mays L.) stalk strength, stalk lodging is still a problem. Identification of traits associated with stalk strength will aid breeders in selecting for lodging resistance and improving maize stalk quality. Anatomical features of stalks of two Missouri synthetic populations (MoSQA and MoSQB) were examined to identify those traits most closely associated with stalk strength. Cycles (C6 low = sixth cycle of selection for low crushing strength, C6 high = sixth cycle of selection for high crushing strength, and C10 high = 10th cycle of selection for high crushing strength) and the original population (C0) of each synthetic were grown 37 064 and 74 129 plants ha-1 at Newark and Georgetown, DE. Stalks of MoSQA had significantly more vascular bundles (C6 low = 338.7, C0 = 375.9, C6 high = 362.7, and C10 high = 368.2) than stalks of MoSQB (C6 low = 281.2, C0 = 304.9, C6 high = 304.4, and C10 high = 317.9). Rind vascular bundles of MoSQA stalks were composed of bundle-sheaths with significantly larger proportional areas (C6 low = 82.54%, C0 = 80.51%, C6 high = 84.05%, and C10 high = 84.34%) than the rind vascular bundle-sheaths of MoSQB stalks (C6 low = 79.79%, C0 = 81.37%, C6 high = 80.81%, and C10 high = 80.79%). Stalks of MoSQB had a significantly larger proportion of hypodermal cell-wall area (C6 low = 76.11%, C0 81.57%, C6 high = 82.33%, and C10 high = 87.42%) compared to stalks of MoSQA (C6 low = 64.32%, C0 = 75.29%, C6 high 72.04%, and C10 high = 75.10%). Anatomical differences between synthetics suggest that MoSQA and MoSQB maintain stalk strength through different struictural compositions. Hypodermal cell-wall area and rind-parenchyma interlumen thickness significantly increased with selection for high crushing strength for both synthetics. The increase in rind-parenchyma interlnmen thickness with selection for high crushing strength is an important consequence of selection given the large area of the maize stalk rind composed of parenchyma cells. Examination of stalk cross-sections of greenhouse-grown-strong, intermediate-strong, and weak-stalk inbred lines (DE811, Wf9, and L317, respectively) revealed anatomical rind component differences. Ear-leaf midrib anatomy reflects rind differences and midribshow promise as a nondestructive selection screen for developing inbred lines and hybrids with stronger stalks to reduce lodging.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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