Personnel:

Project Leader: Jessica Torrion (PI), Bob Stougaard (Co-PI)
Project Personnel: John Garner, Brooke Bohannon

Objective:

To evaluate variety-specific nitrogen use response of irrigated spring wheat for agronomic performance.  

Summary:

Eight spring wheat cultivars were grown under four different nitrogen levels as a split plot, randomized complete block design, with four replications, where nitrogen levels represent the whole plot factor and the spring wheat varieties were the sub plot factor. The four nitrogen treatments included no added fertilizer and 150, 300, and 450 pounds/A, respectively, based on soil test N levels plus supplemental N fertilization. Irrigation was applied when necessary to keep soil moisture from falling below 50% of the plant available water. Other agronomic management procedures are detailed in Table 1.

Significant interactions were observed between nitrogen and variety for protein, days to maturity, test weight and grain moisture. Nitrogen treatment had significant effect on yield and seed size (Table 2). Volt had the highest yield and Brennan and WB Rockland the least. The known inverse relationship between yield and protein is evident (Figure 1). Plant height and falling number were not influenced by the N treatment, but appeared to be strongly related to variety.

Figure 2 shows variety-specific nitrogen use efficiency (NUE) segregated into Partial Productivity (PFP) for the total N input (soil + fertilizer) vs. N from fertilizer input. As expected, NUE for all varieties decreased as 300 lbs N or greater was applied. Consistently, McNeal and Volt had superior NUE followed by Cabernet, Solano, Expresso, and Buck Pronto. WB Rockland and Brennan consistently had the lowest NUEs.

Table 1. Materials and Methods.

Seeding Date: 4/23/14 Herbicide: 5/30/14
Huskie 11 floz/A, Axial XL 16.4 floz/A
Julian Date: 113 Insecticide: 7/1/14
Warrior II 1.5 floz/A
Seeding Rate: 20 plnts/sqft Fungicide: 7/1/14
Headline 7 floz/A
Previous Crop: Canola Harvest Date: 8/26/14
Tillage: Conventional Julian Date: 238
Irrigation: Yes Soil Type: Fine sandy loam
Soil Test: 120-14-69 Fertilizer: ____-10-100

Table 2. Spring wheat nitrogen effects on agronomic performance - 2014.

Variety HT in PM days* SS seeds/lb MC % YLD bu/A PRO % TWT lb/bu TKW g FN sec
                                                                         80 lbs N (no added fertilizer)
Brennan 29.6 85 11,337 13.5 96.4 15.3 60.2 40.0 280
Buck Pronto 29.6 91 9,191 14.1 117.7 13.9 60.5 49.4 376
Cabernet 25.6 93 10,886 13.3 118.6 13.0 59.7 41.7 350
Expresso 27.9 95 11,053 13.5 123.0 14.3 61.0 41.1 373
McNeal 33.2 93 10,013 14.1 129.0 13.4 61.3 45.4 444
Solano 27.1 93 10,600 13.4 119.5 14.2 60.5 42.8 373
Volt 29.6 93 12,077 13.9 130.6 12.7 62.6 37.6 390
WB Rockland 26.6 92 10,435 13.3 106.3 15.5 59.9 43.5 382
                                                                           150 lbs N (soil + fertilizer)
Brennan 28.4 88 11,521 13.4 111.3 15.2 60.8 39.4 283
Buck Pronto 33.3 95 9,251 14.1 126.0 14.8 60.4 49.1 369
Cabernet 26.8 93 11,091 13.0 131.3 13.4 59.6 40.9 333
Expresso 29.1 95 10,967 13.8 130.2 14.4 61.1 41.4 357
McNeal 36.0 94 10,206 14.2 146.5 14.2 61.5 44.5 410
Solano 27.5 94 10,540 13.6 132.1 14.3 60.8 43.1 362
Volt 32.6 95 12,184 14.4 144.6 13.1 62.6 37.3 372
WB Rockland 25.9 95 10,432 13.3 116.0 15.7 60.3 43.5 361
                                                                           300 lbs N (soil + fertilizer)
Brennan 29.3 94 11,623 13.2 105.7 15.5 60.6 39.0 278
Buck Pronto 29.9 94 9,351 14.3 123.0 14.8 59.9 48.6 374
Cabernet 24.9 94 11,189 13.4 126.3 13.4 59.7 40.6 339
Expresso 28.0 95 11,424 13.4 123.9 14.1 60.7 39.7 375
McNeal 32.2 94 10,666 14.2 130.1 14.2 61.1 42.6 410
Solano 26.6 95 10,792 13.5 123.9 14.3 60.7 42.1 366
Volt 29.7 96 12,340 14.1 141.6 13.1 62.4 36.8 386
WB Rockland 27.4 95 10,788 13.1 112.7 15.7 60.2 42.1 381
                                                                           450 lbs N (soil + fertilizer)
Brennan 27.6 93 11,547 13.2 101.5 15.7 60.7 39.3 297
Buck Pronto 28.8 95 9,338 14.3 115.3 15.1 60.0 48.6 360
Cabernet 27.0 93 11,270 13.0 115.0 13.9 59.6 40.3 333
Expresso 27.8 96 11,388 13.7 118.6 14.6 60.5 39.9 348
McNeal 32.8 96 10,635 14.1 130.8 14.6 60.8 42.7 423
Solano 25.7 94 11,016 13.5 113.5 14.4 60.2 41.2 346
Volt 30.4 94 12,542 14.4 135.5 13.0 61.9 36.2 383
WB Rockland 27.8 95 10,552 13.2 105.6 15.8 60.0 43.0 361
CV 12.1 3.1 8.3 3.7 12.8 7.3 1.4 8.5 13.1
LSD 2.0 2.1 216.0 0.2 7.6 0.6 0.9 0.9 32.0
Pr>F (0.05) - N 0.152 0.007 0.002 0.419 0.002 0.090 0.007 0.002 0.435
Pr>F (0.05) - Var <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001
Pr>F (0.05) - NxVar 0.824 <0.0001 0.881 0.041 0.484 0.010 0.019 0.831 0.899

HT: height; PM: physiological maturity *(duration from emergence); SS: seed size; MC: moisture content; YLD: yield; PRO: protein; TWT: test weight; TKW: thousand kernel weight; FN: falling number

figure 1

figure 2