Objective  Genetic inheritance of crop yield and kernel sugar content relating to measurements of three leaves nearby an ear on a waxy maize plant was examined for correlation to facilitate breeding and quality prediction.

  Methods   Six inbred waxy maize lines were cross-bred with 15 key inbred lines based on an incomplete diallel hybridization of NCII design. At harvest, yield of ears, soluble sugar content of kernels, dimensions of the three leaves closest to an ear, and 10 additional traits of the hybrids were measured 21 d after pollination. Ear yield by weight and kernel sweetness by Brix were obtained. Dimensions of the leaves located above, at, and below an ear on a plant were measured to correlate with the general combining ability (GCA) and special combining ability (SCA) on kernel yield and sweetness of the hybrids passed on from their parents.

  Results   Correlations were found between the leaf length and the ear yield and between the leaf width and the kernel sugar content. However, the narrow heritability of leaf length and ear yield was relatively low, mostly shown by the SCA on length of lower ear-leaf and weight of corn-on-the-cob. On the other hand, that of leaf width and sugar content was significant and mainly the GCA on width of upper ear-leaf and kernel sugar.

  Conclusion   The width of upper ear-leaf grown next to an ear significantly reflected the sweetness of the kernels born on a waxy maize plant. Thus, the measurement could potentially be used as a visual, easily assessable indicator for cultivars selection in breeding and/or quality estimation in forecasting a harvest.