COMBINING ABILITY ANALYSIS OF NORMAL, SUGARY-2, OPAQUE-2, AND SUGARY-2 OPAQUE-2 ZEA MAYS L. INBRED LINES; EFFECT OF SUGARY-2 AND OPAQUE-2 ON SOME MORPHOLOGICAL TRAITS IN ZEA MAYS L. HYBRIDS; AND INTERACTION OF OPAQUE-2, SUGARY-2, AND SHRUNKEN-2 KERNELS WITH PHENOTYPICALLY NORMAL KERNELS ON EARS OF HETEROZYGOUS ZEA MAYS L. HYBRIDS

STEVE GREY BALLENGER, Purdue University

Abstract

Normal, sugary-2 (su2), opaque-2 (o2), and sugary-2 opaque-2 (su2o2) versions of Zea mays L. inbred lines A632, B37, B14A, B73, and H93 were crossed with similar versions of A619, H99, H98, Mo17, and H95 to produce four corresponding factorial mating designs. Crosses were grown at Homestead, FL in winter 1977-1978 and West Lafayette, IN in 1978. Yield, protein percentage, protein/ha, lysine percentage of protein, and lysine/ha were determined. General and specific combining ability effects were estimated for yield, protein percentage, and lysine percentage of protein. Normal crosses yielded highest and su2o2 crosses had the highest protein percentage and lysine percentage of protein. In spite of lower yields, su2o2 crosses averaged more protein and lysine per unit area than o2 crosses. This indicates su2o2 crosses may be more desirable than o2 crosses where premiums are paid for high quality protein. General combining ability for yield and protein percentage were influenced less by genotype than specific combining ability, whereas general and specific combining ability for lysine percentage of protein were both influenced by genotype. This indicates yield or protein percentage are better criteria for selection of germplasm for conversion to su2, o2, or su2o2 than lysine percentage of protein. The hybrids in Section I plus similar versions of twenty additional hybrids comprised the materials for Section II. Yield, kernel weight, kernel row number, plant height, and ear height were measured at Homestead and West Lafayette. Days to midsilk, leaf area, and days to black layer were measured at West Lafayette. Significant differences between genotypes were found in some crosses for kernel row number, plant height, ear height, and leaf area. Where differences were found, su2o2 crosses generally had more kernel rows, shorter plant or ear height, and smaller leaf area. Also, su2 crosses had more kernel rows and o2 crosses had smaller leaf area in some cases. These differences may have been caused directly by su2 or o2, or indirectly by residual genetic variability, genes closely linked to su2 or o2, or differences in seed quality between genotypes. Phenotypic correlations were influenced only slightly by su2 or o2. Normal (+/+), homozygous o2 (o2/o2), homozygous su2 (su2/su2), heterozygous o2 (+/o2), heterozygous su2 (+/su2), and heterozygous shrunken-2 (+/sh2) versions of 'Oh43 x B37', 'Oh43 x W64A', and 'W64A x B37' Zea mays L. hybrids were grown at the Purdue Agronomy Farm in 1977 and 1978. Ears were self-pollinated, hand-harvested, and force-air dried. Kernel row number was determined and kernels were separated into phenotypic classes. Weight, volume, density, protein percentage, and protein/kernel were determined for each phenotypic class. Normal kernels from +/+ and +/sh2 plants had similar weight, volume, and density. However, in two hybrids, normal kernels for +/sh2 plants had greater protein percentage and protein/kernel than normal kernels from +/+ plants. This suggests normal kernels on +/sh2 plants may have assimilated nitrogen compounds that sh2 kernels were unable to assimilate. Normal kernels from +/+, +/o2, and +/su2 plants were similar for all traits, although su2 dosage effects may have been stronger for 'W64A x B37' than the other hybrids.

Degree

Ph.D.

Subject Area

Agronomy

COinS