Genotypic effects on field performance of maize plants carrying the allele sugary1

Some mutants reduce fitness when incorporated into breeding populations, particularly the allele sugary1 ( su1 ) into maize ( Zea mays L.). The objective of this study was to compare in different maize genetic backgrounds the performance of plants carrying su1 . The crosses among three su1 populations and three Su1 synthetics were random-mated three times. The Su1 and su1 plants were evaluated separately. The su1 plants had poorer performance than the Su1 plants, particularly at earlier stages of development, and early vigour seemed to be the most limiting factor for su1 plant development. The differences in performance between su1 and Su1 plants decreased during plant growth and were not significant for most adult traits. Specific combinations of donors and recipients of the su1 allele had different effects on performance of su1 plants. These results suggest that the use of defective mutants in plant breeding should take into account the genotypic effects on mutant fitness.