Relationships among phenotypic traits of sweet corn and tolerance to crowding stress

Abstract

Crowding stress tolerance is defined as the extent to which the crop maintains yield per unit area as plant population density increases beyond standard levels. Sweet corn (Zea mays L.) hybrids grown for processing vary widely in tolerance to crowding stress; however, the mechanisms involved in crowding stress tolerance are unknown. The objective of the study was to determine the extent to which crop traits, individually and in combination, relate to crowding stress tolerance in processing sweet corn. Twenty-six modern shrunken-2 processing hybrids from eight sources were grown under conditions of crowding stress (i.e. 72,000 plantsha−1) over a three-year period. Seventeen crop traits measured from emergence to harvest were related to four measures of crowding stress tolerance, including ear mass, recovery, case production, and gross profit margin. Of individual crop traits, kernel mass plant−1 was among the best predictors of crowding stress tolerance in processing sweet corn, as long as sweet corn lines were grown at a uniformly high plant population. Two categories of traits related to crowding stress tolerance in sweet corn, including a ‘source-sink relationship’ factor and a ‘photosynthetic capacity’ factor. Factor regression showed the combination of traits loading into the source-sink relationship factor was positively related to ear mass, case production, and gross profit margin. This research points to the underlying mechanisms involved in crowding stress tolerance in processing sweet corn.