Decomposing Site x Environment Interactions on Pea Yields in Montana.

Decomposing Site x Environment Interactions on Pea Yields in Montana

Michael Bestwick, Chengci Chen, and Rick Engel

Montana State University

An expanding pulse industry has set Montana as the nation’s leading field pea (Pisium sativum L.) producer. Since 1998, planted pea acreage has risen from 35,000 to nearly 600,000 acres across the state.  In order to sustain the pulse industry in Montana, knowledge on impacts of climatic stress by environment interactions on pea yields in Montana is needed. The objectives of this study are to a) identify environment by climate interactions on pea yields through multiple linear regression, and b) decompose these interactions using simulation based approaches.  

Multiple regression analysis showed that precipitation and Modified Penman Reference Evapotranspiration (ET_o) could explain 65 and 72 percent of the variability in mean pea yield across five sites respectively over a 250 growing degree day window bracketing flowering, but site x climate interactions were highly significant. These interactions were decomposed using simulations based on the Agricultural Reference Index for Drought (ARID) soil water balance, which integrates site specific soils and climatic inputs to generate an ARID drought index. Using the simulated ARID index as an explanatory variable in simple linear regression, nearly half the variation in mean pea yield was explained.

Although the ARID regression had weaker explanatory power relative to the multiple regression models, it provides a more mechanistic basis for breeders and farmers to improve line advancement efforts and site specific management across Montana’s diverse climate and soils.