Planting date effects on winter triticale grain yield, dry matter production, and N accumulation
Winter triticale (XTriticosecale Wittmack) has the potential to introduce valuable economic and environmental benefits to U.S. grain production systems. In order to maximize triticale value, research was conducted to identify planting dates that allow maximum productivity after soybean [Glycine max (L.) Merr.]. Winter triticale was planted at 10-d intervals from 15 September to 15 October at three Iowa locations: central, northeast, and southwest over three growing seasons: 2001-02, 2002-03, and 2003-04. Grain yield, dry matter yield, and N accumulation tended to be greatest in southwest Iowa. Spring dry matter and N accumulation occurred at a faster rate for September planting dates than October dates. Early season N concentrations were much greater for late-planted triticale, possibly due to younger tissue in the plants. September planted triticale harvested in mid-May produced approximately 2 Mg ha−1 more dry matter than October planted triticale, averaging 4.3, 3.5, and 5.8 Mg ha−1 dry matter with protein concentrations of 125, 144, and 109 g kg−1 in central, northeast, and southwest locations, respectively. Grain and straw N concentration tended to increase with delayed planting. Delaying planting from late-September to mid-October reduced grain yields from 3.64 to 3.23, 3.30 to 2.83, and 4.89 to 3.66 Mg ha−1 in central, northeast, and southwest locations, respectively. Spikes m−2 decreased from 469 to 393 and seed spike−1 increased from 35.9 to 39.4 as planting was delayed from mid-September to mid-October. Increased seeds spike−1 could not fully compensate for decrease spikes m−2 with delayed planting, making spikes m−2 the most influential component of grain yield as planting was delayed. Planting date did not affect seed weight. Grain and forage yield was greatest when at least 300 growing degree days (GDD) (base 40C) accumulated between planting and 31 December. Winter triticale would most likely be placed after soybean in a grain crop rotation in the central U.S. Corn and Soybean Belt. Our results suggest that a two to three week period would be available for planting winter triticale after soybean in Iowa without diminished yield caused by late planting.