Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/7/2013
Publication Date: 3/21/2014
Citation: Liang, Z., Bronson, K.F., Thorp, K.R., Mon, J., Badaruddin, M., Wang, G. 2014. Cultivar and nitrogen fertilizer rate affect yield and nitrogen use efficiency in irrigated durum wheat. Crop Science. 54:1175-1183. Interpretive Summary: After water, nitrogen is the most important resource required for crop production. Excessive use of nitrogen fertilizer contributes to environmental degradation because fossil fuels are burned to produce the fertilizer and because nitrates from agricultural fields leach to surface water and groundwater. Therefore, research efforts are needed to find better ways to manage nitrogen resources. The purpose of this study was to evaluate alternative indies from a SPAD meter, a commercial device that measures the level of chlorophyll in plant leaves. Agronomic experiments in 2010-2011 and 2011-2012 were conducted to investigate the effects of cultivar and N fertilizer rate on grain yield and nitrogen use efficiency under irrigated desert conditions in central Arizona. A variety of agronomic measurements were made, including grain nitrogen concentration, grain nitrogen weight, total nitrogen uptake, nitrogen harvest index, nitrogen utilization efficiency, nitrogen uptake efficiency, and agronomic efficiency. The study showed that there was significant variation in grain yield and nitrogen use efficiency among durum wheat cultivars, but the nitrogen fertilizer effects were more significant than the cultivar effects. The results are useful for nitrogen fertility research in durum wheat, and the results are also being extended to durum wheat growers in central Arizona.
Technical Abstract: Optimizing nitrogen (N) management and using cultivars with high N use efficiency (NUE) are of great importance for durum wheat (Triticum durum L.) producers in irrigated desert production systems. Field experiments with six durum wheat cultivars (Ocotillo, Orita, Kronos, Havasu, Duraking, and Topper) were conducted with five N fertilizer rates (0, 73, 123, 185, and 269 kg ha-1) in 2010-2011 growing season and an additional N fertilizer rate of 403 kg ha-1 in 2011-2012 growing season to investigate the effects of cultivar and N fertilizer rate on grain yield and NUE under irrigated desert conditions. Durum wheat cultivars differed in grain N concentration (GNC), grain N, total N uptake, nitrogen harvest index (NHI), N utilization efficiency (NUtE), and agronomic efficiency (AE) in the 2010-2011 growing season. In the 2011-2012 growing seasons, cultivars differed in grain yield and all N measurements. As N fertilizer rate increased, grain yield, GNC, and total N uptake increased and then plateaued. Agronomic efficiency and NUtE decreased linearly and N uptake efficiency (NUpE) and NUE decreased as a power function with increased N fertilizer rates. Durum wheat NUE was more closely related to NUpE compared to NUtE. Nitrogen harvest index increased from 65% in the unfertilized treatment to 71% at the 195 kg ha-1 N fertilizer rate and then dropped to 64% at the 403 kg ha-1 fertilizer rate. In summary, there was significant variation in grain yield and NUE among durum wheat cultivars, but N fertilizer effects were more significant as compared to cultivar effects.