Testing the effects of moisture on seedcoat color of pinto dry beans

Seedcoat color is an important trait, as it affects marketing and consumer acceptance of pinto beans (Phaseolus vulgaris L.). Pinto breeding line NE 9 4-4 showed seedcoat yellowing in on-farm field trials in Nebraska in 1996 a nd 1997. Hail, sprinkler irrigation, and fall rainfall appeared to be invol ved in increasing seedcoat yellowing, based on analysis of field and weathe r data of on-farm trial sites. The objective of this study was to determine the effect of moisture on seedcoat yellowing of pinto line NE 94-4 (suscep tible) and pinto 'UI-114' (highly resistant). Two greenhouse experiments we re conducted involving misting of bean plants near maturity and injecting w ater into maturing bean pods. Another experiment evaluated the response of seeds of these two bean entries to moisture by placing them on moist filter paper in petri dishes in the laboratory. Results showed that both genotype and moisture content are involved in seedcoat yellowing. This simple, chea p, and effective filter paper test was then used to evaluate seedcoat yello wing of nine pinto genotypes in response to moisture. Pinto NE 94.4 and 'Ko diak' showed the greatest change, while 'Bill Z' showed the least change, i n seedcoat color.