Hybrid and nitrogen influence on pearl millet production in Nebraska: Yield, growth, and nitrogen uptake, and nitrogen use efficiency

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a staple grain crop in the arid and semiarid regions of Africa and India, and a new grain crop in the USA. A 2-year field experiment was conducted near Mead, NE, in 1995 and 19 96 on a Sharpsburg silty clay loam (fine, smectitic, mesic Typic Argiudoll) soil with approximately 29 g kg(-1) organic matter, 35 kg ha(-1) NO3-N, an d pH of 6.0. The objective was to determine the influence of hybrid and N o n grain yield, dry matter accumulation and partitioning, and growth rates t hroughout the growing season. Nitrogen concentrations, uptake, and use effi ciency were also determined. Treatments were a factorial combination of the pearl millet dwarf hybrids (59022A x 89-0083, 1011A x 086R, and 1361M x 6R m) and N levels (0 and 78 kg ha(-1)) in a randomized complete block design. Two plants per plot were sampled at 2-wk intervals and partitioned into pl ant parts, dried, weighed, and analyzed for N concentration. Applied N incr eased grain yield by 0.4 to 0.5 Mg ha(-1), but had only a small effect on d ry matter accumulation and partitioning. Hybrid differences were small for grain yield. Pearl millet dry matter accumulation increased cubically in bo th gears, with maximum crop growth rates among hybrids ranging from 0.48 to 0.57 g m(-2) per growing degree day (GDD) in 1995 and ranging from 1.9 to 3.1 g m(-2) GDD(-1) maximum in 1996. The relative growth rate among hybrids declined from 0.012 to 0.020 g(-1) m(-1) GDD(-1) in both gears to near zer o at physiological maturity. Nitrogen concentrations were higher during the vegetative stages and decreased with plant age. Applied N decreased N use efficiency for aboveground biomass (NUE1) by 18 to 25 g DM g(-1) N, and N u se efficiency for grain (NUE2) by 7 to 12 g gain g(-1) N. Environmental var iability due to years had a greater effect on yield, growth, and N levels t han hybrid and applied N.