Factors affecting seed coat yellowing of pinto beans

Abstract

he pinto bean breeding line 94-4 (Phaseolus vulgaris L.) showed seed coat yellowing in on-farm fi eld trials in Nebraska in 1996. After reviewing weather data, sprinkler irrigation appeared to be one of the cultural factors involved with increase in seed coat yellowing. Cultural conditions were again investigated 1997 in on-farm trials. In one test half of the NE 94-4 plants were cut and combined promptly while the other half of the cut plants were left on the ground, rained upon, and combined later. Seed from the pods of former and latter treatments were compared for degree of seed coat yellowing. Yellowing was recorded visually by determining percentage of the yellow area on a bean seed. The seed from the pods of the cut wetted plants showed more discoloration than seed from the plants that were not rained on. In another experiment two or four samples (40 g each) were taken from each of seven cultivars as well as NE 94-4 to determine degree of yellow discoloration of seed. The percent seed coat yellowing of the varieties/line was as follows: ‘Apache’ 12.5%, ‘Bill Z’ 14.9%, ‘Buckskin’ 20.7%, ‘Chase’ 9.2%, ‘NE-94-4’ 54.1%, ‘179’ 48%, ‘Vision’ 35.5%, ‘Winchester’ 10%. Results of pigment extraction and simulated irrigation experiments will be presented in order to better explain the cause of pinto seed coat yellowing