Nitrogen Response, Uptake and Use Efficiency of Spring Wheat Cultivars

One of the most common questions asked by wheat producers is how to manage nitrogen (N) fertilizer depending on what variety they chose to grow. Previous work has shown that wheat cultivars may vary in N requirements, N uptake, and N use efficiency (NUE).

One of the main reasons why many producers like to plant older varieties is the fact that they are very familiar with them, even though they may be substantially lower yielding, may not have the best grain quality and may not perform as well under various biotic and abiotic stresses associated with disease, water or nutrient limitations or pest or weed pressure.

Increasing the knowledge about newly released varieties will help to improve the adaption of these varieties by growers. 

Field experiments were established at Parma R&E Center in Spring of 2019. Six spring wheat varieties – hard red spring (hard red spring – SY Basalt, Jefferson) and hard white spring (hard white spring – UI Platinum, Dayn), and (soft white spring – UI Stone, Seahawk) – were planted. Each variety was evaluated under 7 N rates (0, 50, 100, 150, 200, 250, and 300 kg N ha-1) applied as granular urea (46-0-0).  Treatments were arranged in a randomized complete block design (RCBD) with four replications.
The following data were collected from the research area (a dedicated 0.2 m2 section within each plot) at Feekes 5, and Feekes 10:

• plant height (by measuring height of 10 randomly selected plants per plot)
• chlorophyll content estimate (using SPAD meter)
• biomass production estimate- as Normalized Difference Vegetative Index (NDVI, using GreenSeeker handheld optical sensor)
• biomass weight (by hand-harvesting all above ground biomass within the 0.2 m2 area)
• biomass N content (laboratory analysis)
• biomass N content and final grain yield were estimated using multispectral camera mounted on a UAV

The performance of each variety was evaluated using multispectral camera mounted on a UAV
At maturity, the following data was obtained:
crop yield – preliminary results are reported in Figure 1.
grain nutrient content (grain will be analyzed for N content) – newly purchased Perten Grain Analyzer will be utilized.
Wheat grain quality will be assessed: 1) baking quality analysis (mixing time, water absorption, loaf volume, crumb grain score), 2) solvent retention capacity (SRC) will be carried out at the University of Idaho Wheat Quality Lab, 3) viscosity (Hageberg Falling Number test) will be performed at the Aberdeen R&E Center lab.
OBJECTIVES:

• To assess response of newest University of Idaho, other best-performing wheat cultivars, and traditional “check” varieties to N, to quantify their N uptake magnitude and its’ pattern throughout the growing season, and NUE, and
• To evaluate N uptake and NUE of spring wheat varieties currently tested in extension nurseries using ground- and aerial-based data.