Pericarp thickness of two groups of single cross maize hybrids (164 experimental and 30 commercial) and 79 parental inbred lines, grown in 1976 in performance tests and inbred nursery at VIMMES, was measured using the method described by Helm and Zuber (Crop Sci. 1972, 12:428-430). Pericarp thickness varies from 48 to 122 microns in hybrids, and from 42 to 124 microns in inbreds. Relationships between pericarp thickness and grain yield, kernel length, kernel width, kernel cross-section size, kernel weight, kernel volume, and kernel row number of hybrids were studied (Table 1).

Table 1.

Pericarp thickness of the two groups of hybrids does not correlate significantly to grain yield (r = -0.02 and 0.27 respectively), and to kernel length (r = 0.10 and 0.23). Significant positive correlation was found between pericarp thickness and kernel width (r = 0.33*** and 0.66***), size of kernel cross section (r = 0.38*** (Fig. 1), kernel weight (0.42*** and 0.51***) and kernel volume (r = 0.22** and 0.60***). Significant negative correlation (Fig. 2) was found between pericarp thickness and kernel row number.

Figure 1.

Figure 2.

Purdy and Crane (Crop Sci. 1967, pp. 294-297) reported that the pericarp thickness is an important factor in moisture loss from the maize kernel after physiological maturity. Data obtained in this experiment show that an increasing of the kernel row number and kernel length, and a decreasing of the kernel width, contribute to thinner pericarp in breeding for high yielding and fast drying maize.

Trifon M. Georgiev

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