TWO CYCLES OF SELECTION FOR INCREASED WEIGHT OF AMYLOSE-EXTENDER KERNELS RELATIVE TO NORMAL KERNELS IN THREE EARLY BACKCROSS VERSIONS OF HIGH-AMYLOSE MAIZE (ZEA MAYS L.)
Abstract
Amylose, one of two starches in corn, has several industrial uses. With the discovery that the amylose-extender (ae) gene increased the percentage of amylose present in the endosperm, considerable effort was made to develop high-amylose varieties. However, yields for high-amylose corn average 65-75% of ordinary dent varieties. Growers of high-amylose varieties are paid a premium because of the reduced yields and the necessity to isolate the corn at all stages of production and handling. Using three early backcross versions of high-amylose corn (a(,3), a(,43), ('a)B(,73)), two cycles of selection were initiated in an effort to improve the yield of ae kernels, relative to normal kernels. The selection unit was the ratio of the weight of 50 ae kernels:50 normal kernels, within a segregating ear. Approximately the top 10% of each population was selected each cycle. No significant improvements were made in any of the backgrounds during the selection process. In general, it would appear that rather than attempting to improve the yield of ae lines, it would be more beneficial to concentrate on the introduction of the ae allele into high yielding varieties.
Degree
Ph.D.
Subject Area
Agronomy
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