Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 2, 1999
Publication Date: N/A
Interpretive Summary: Field pea is an important rotational crop for wheat and other small grain crops in the Palouse Region of the U.S. Pacific Northwest. The region is characterized by rolling hills with 30-40% slopes where rainfall and runoff from melting snow contribute to severe soil erosion. Currently, the dry pea crop produces insufficient crop residue to prevent soil erosion in the subsequent winter wheat crop. Germplasm was evaluated for potential to increase residue production without seed yield reductions. The positive relationship between residue production and seed yield indicates that it is possible to increase seed yield and residue production simultaneously. Despite strong environmental influence on residue production and seed yield, improvements in residue production can be realized through the use of germplasm with greater potential for vegetative growth. Germplasm enhancement efforts should focus on selection for a constant harvest index in breeding populations with increased vegetative growth. Increased amounts of crop residue left by pea crops will reduce the erosive effects of fall rains and runoff thereby improving sustainability of crop production in areas where peas are grown.
Technical Abstract: Pea (Pisum sativum L.) cultivars, grown for their dry edible seed, produce small and fragmentary harvest residues. The small residue pieces are ineffective in controlling soil erosion when the pea crop is followed by winter wheat in rotation. This presents a special problem for pea-wheat rotations common on the steep loess hills of the Palouse region of the U.S. .Pacific Northwest. To determine the amount of residue produced by dry pea total aboveground biomass was harvested from a 0.3 to 0.4 m section of the second row in each plot of the advanced pea yield trials conducted by the USDA at three locations in the Palouse region. Samples were collected in 1993, 1994 and 1995 and the amounts of residue produced were measured. Individual entries produced from 2300 to 4760 kg/ha of total biomass. Mean harvest indices for the nurseries ranged from 35% in 1994, a dry year, to 47% in both 1993 and 1995. Seed and residue yields were smaller in 1994 than in 1993 and 1995. Residue production and seed yield were influenced by sowing date and the amount and distribution of precipitation. Despite large environmental effects on residue production, sufficient genetic variation to improve the residue yields of dry pea was observed. The large, positive and significant correlation between seed yield and residue production indicated that it is possible to increase seed yields simultaneously with residue production through the incorporation of germplasm with greater potential for vegetative growth.