Soybean response to relay intercropping systems

Relay intercropping soybean (Glycine max L. Merr.) into (Triticum aestivum L.) winter wheat may allow producers to increase soybean yields compared to double-cropping. Research was conducted to compare soybean response to the effects of row orientation when relay intercropped into winter wheat. Agripro 'Victory' wheat was planted in solid intercropped (SI) and skip-row intercropped (SRI) patterns near Manhattan and Rossville, Kansas in 1988 and 1989. Row orientation was north-south (NS) or east-west (EW). 'Resnik' soybean was intercropped into wheat at late boot. In 1989, NS wheat yield was 11% greater. Planting pattern did not influence wheat yield. Skip-row intercropped soybean plots had 51% greater soybean yields than SI plots. Row direction did not influence soybean yield. Research was also conducted to compare effects of water regime, planting pattern and wheat cultivar on relay intercropped soybean. Five winter wheat cultivars were planted in SI and SRI patterns near Manhattan and Rossville, KS in 1988 and 1989. Resnik soybean was sole cropped (SC) for comparison, and intercropped when wheat was at late boot in 1989, and at late boot and dough in 1990. Short wheat cultivars allowed greater light penetration to soybean. Skip-row intercropped wheat yields were 8% lower than solid sole crop wheat. Soybean dry matter at wheat harvest was influenced by wheat cultivar. Soybean in SRI patterns accumulated more dry matter and produced greater seed yields than SI soybean. Irrigation increased soybean yield 16% at Manhattan and enhanced soybean survival in the relay system. Skip-row intercropped soybean used significantly more moisture than SC soybean in either water regime. Dense wheat canopies significantly reduced soybean populations and yields. Maturity group III and IV soybean were evaluated for response to 0, 60 and 70% shade at Manhattan in 1989 and 1990. Dry matter accumulation decreased and stem length increased significantly in both maturity groups as level of shade increased. Cultivars within maturity groups responded similarly to shade. Winter wheat cultivars were evaluated for PAR penetration capabilities at three environments. In some environments, short, early maturing wheat cultivars allow greater penetration of the canopy than tall, late cultivars. Wheat leaf type did not influence light penetration.