Evaluation of yield and agronomic performance of leafed and semi-leafless pea blends

Field pea (Pisum sativum L.) has two distinct leaf morphologies, leafed (L) and semi-leafless (SL). Grown together, SL and L pea blends have better weed control and higher crop yield than sole crops of either leaf type. Previous studies have only investigated mixing leaf types from two distinct varieties, and therefore the blend could be affected by traits specific to each pea variety rather than the difference in leaf type. To determine if yield and agronomic improvement of pea leaf blends are due solely to leaf type, this study (a) compared leaf blends of near-isogenic lines with the same varieties grown in monoculture, and (b) determined whether intercepted solar radiation, disease-resistance, lodging performance, biomass, and yield were improved by growing a varietal mixture. Five field experiments tested all possible pairings of four near-isogenic L and SL lines in a single ratio (75:25, SL/L), compared with monocultures (100% SL or 100% L). The results found that the leaf-type blends had 11% less lodging than the L monoculture and had an 8.5% greater seed yield than the L monoculture in one variety. The near-isogenic blends and non-isogenic blends did not differ significantly for foliar disease, lodging, biomass, yield, and yield stability. Consequently, the exhaustive comparison of near-isogenic or non-isogenic blends grown under multiple environments indicates that SL and L pea blends have nonsignificant yield and agronomic advantages compared with SL monocultures.