ROW ORIENTATION AND PLANTING PATTERN OF RELAY INTERCROPPED SOYBEAN AND WHEAT

Relay intercropping soybean [Glycine max (L.) Merr.] into winter wheat (Triticum aestivum L.) may increase soybean yields compared with doub lecropping. Once the soybean crop is established, however, it competes with wheat, which may lead to reductions in soybean plant population and seed yield. A skip-row planting pattern of wheat has been shown to reduce intercrop competition and increase soybean productivity. Row o rientation may also influence soybean seedling survival and seed yield . We conducted research to compare soybean response to the effects of row orientation and planting pattern when relay intercropped into wint er wheat. Agripro 'Victory' wheat was planted in solid intercropped an d skip-row intercropped patterns near Manhattan and Rossville, KS, in 1988 and 1989. Row orientation was north-south or east-west. 'Resnik' soybean was intercropped into wheat at late boot. In 1989, wheat yield was 11% greater from north-south rows than east-west rows. Planting p attern did not influence wheat yield. Solid wheat stands were detrimen tal to soybean seedlings. Solid intercropped soybean had 29% stand red uctions, and 34% lower yields than skip-row intercropped soybean. Phot osynthetically active radiation from soybean emergence to late milk st age of wheat was from 3 to 63% greater in skip-row intercropped vs. so lid intercropped plots depending upon row direction and time of day. R ow direction did not significantly influence soybean yield.