Effects of Recurrent Selection for Crushing Strength on Morphological and Anatomical Stalk Traits in Corn 1

Twelve morphological and anatomical traits were evaluated in two synthetics of corn, Zea mays Lo, which had undergone selection for high and low crushing strength. The two synthetics were represented by third cycle selections designated ‘MoSQ A‐High,’ ‘MoSQ A‐Low,’ and ‘MoSQ B‐Low.’ The study was conducted to determine whether selection for stalk strength resulted in corresponding changes in one or more anatomical traits. Most of the traits evaluated were affected by selection. Significant differences, however, were not detected among the four sub‐populations for rind density. Multiple regression coefficients indicated that stalk density and rind density were relatively less important than rind weight and area of rind in predicting rind crushing strength. The area of vascular bundles, the area of lignification, and the we;.ght of rind and stalk section were correlated with rind crushing strength responses to selection. MoSQ A and MoSQ B were similar in stalk strength, but derived their essentially equal strength in different ways. MoSQ A had greater number of vascular bundles than MoSQ B, and vascular bundle number was greater for the high than for low selections. MoSQ B had more lignification per vascular bundle than MoSQ A, and the lignified area in the rind was correlated with crushing strength. We concluded that populations may differ in the particular array of anatomical traits that contribute to stalk strength. Nevertheless, strength in this study appeared to reside principally in the rind tissue.