Factors associated with emergence of Shrunken-2 maize in Korea

Abstract

Seventeen supersweet Shrunken-2 (sh-2) maize lines and progenies of their crosses to two sh-2 hybrid testers were investigated for factors responsible for differences in field emergence in Korea in studies carried out in the field, greenhouse and laboratory. The lines and their testcrosses showed significant genetic variation for emergence. Two lines showed significant positive general combining ability (GCA) for emergence while two other lines had significant negative GCA effects. Because none of the specific combining ability effects was significant, emergence was primarily influenced by additive gene action, and could, therefore, be improved by recurrent selection. Seed weight was significantly (P<0·05) correlated with emergence for inbreds (r=0·63) and testcross progeny involving the tester with the lower mean seed weight (r=0·54). Two lines also showed significant positive GCA effects for seed weight. The lines with positive GCA effects for emergence were different from those with positive GCA for seed weight, indicating that factors other than seed weight influence field emergence. The severity of Fusarium infection of seeds of the lines was significantly correlated to germination (r=−0·61, P<0·05) and emergence (r=−0·67, P<0·01), suggesting that practices that prevent pathogenic field infection, such as timely harvest and treatment with fungicides, are crucial for high seed quality. The field emergence of sh-2 inbred parents did not give an indication of emergence in hybrid combinations.