Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2020
Publication Date: 5/19/2020
Citation: Miklas, P.N., Osorno, J., Cichy, K.A. 2020. Agronomic performance and cooking quality characteristics for slow darkening pinto beans. Crop Science. 60(5):2317-2327. https://doi.org/10.1002/csc2.20220.
Interpretive Summary: Pinto beans are the most important dry bean market class grown in the U.S. There is a new gene 'sd' that slows after-darkening of pinto bean seed coats in storage or when field harvest is delayed. This slow darkening trait has quickly become incorporated into pinto beans. We wanted to study the effect this quick introgression of the sd gene has had on field performance and cooking quality traits of pinto beans. We compared slow darkening with regular darkening pinto bean breeding lines and cultivars grown across multiple environments in North Dakota and Washington from 2010 to 2018. Results indicate slow darkening pinto beans yield less, have smaller seed size, and lodge more than regular pintos. However, breeders are making progress in developing slow darkening pintos that combine higher yields with larger seed size and reduced lodging. Slow darkening pintos cooked 20% faster than regular pintos in one population. Fast cooking time is a desirable trait for beans in developing countries because cooking fuel is expensive. Slow darkening pintos had slightly better canning than regular pintos. Overall breeders should concentrate their efforts on improving agronomic performance of slow darkening pinto beans. Additional research is warranted to confirm that slow dark pintos cook faster than regular pinto beans.
Technical Abstract: Slow darkening (SD) pinto beans possess a desirable new trait conditioned by the recessive sd gene that slows seed coat darkening under storage and delayed harvest. The effect sd may have on performance needs investigation. We examined agronomic performance and cooking quality of slow darkening pinto beans. There were 30 (15 SD and 15 RD – regular darkening) recombinant inbred lines (RILs) from each of two populations. The 60 RILs were tested across three locations in North Dakota and Washington. In addition, advanced SD and RD pinto breeding lines were tested in trials from 2010-2012 and in 2018. Across trials, the SD pintos as a group had significantly poorer emergence, greater lodging, less yield and smaller seed size, compared to the RD group. Agronomic performance for recently bred SD pinto breeding lines improved slightly in comparison to RD pintos for only a few traits (seed yield, lodging, emergence) in 2018 compared to earlier bred materials tested in the 2010-2012 trials. Breeders should continue to focus on improving agronomic performance of slow darkening pinto bean. Further research on cooking time is warranted given that SD RILs cooked 20% faster than RD RILs in one population. Faster cooking is a beneficial trait for developing countries where cooking fuel is scarce. Overall, SD pintos exhibited slightly better canning quality than RD pintos. Whether raw or cooked SD were much lighter in color than RD pintos, emphasizing the need to keep them separated as distinct market classes.