Winter triticale in the semiarid U.S. Pacific Northwest drylands

The low-precipitation (<14 inch annual) zone of the inland Pacific Northwest (PNW) of the U.S. covers roughly 4.5 million cropland acres in a belt through east-central Washington and north-central Oregon. The Mediterranean-like climate produces wet winters and dry summers. A monocrop two-year rotation of winter wheat–fallow (WW-F) is practiced on >90% of the land. Researchers and farmers have for many decades sought alternative crops and rotations that are equally or more stable and profitable than the WW-F system. A multitude of cereal and broadleaf spring-sown crops so far tested by farmers and researchers in the PNW drylands have not had stable yields nor been economically viable in the long term because of heat and/or water stress encountered during their reproductive period.

In the past 10–15 years, three relatively new winter crops have garnered interest in the region. These crops are winter triticale (WT), winter pea, and winter canola. As with WW, these three new winter crops need to be planted in late August–early September into moisture accumulated in the soil after a 13-month fallow to achieve optimum grain yield potential. Waiting to plant until the onset of fall rains in mid-October or later results in severe yield decline.

Both forage and grain types of triticale are grown. The focus here is grain triticale. Triticale grain is primarily fed to ruminants, pigs, and poultry as it is a good source of protein, amino acids, and B vitamins. Triticale is widely considered to have better tolerance to both saline and low-pH soil conditions compared with wheat. Additionally, triticale is less susceptible to rusts than is wheat, including stripe rust which is a major fungal disease in wheat.

The Experiment

A nine-year dryland cropping systems field experiment was conducted during the 2011–2019 crop years at the Ron Jirava farm near Ritzville, WA to compare the agronomic and economic feasibility of WT compared with WW. Silt-loam soils at the site are >6 ft deep with no rocks or restrictive layers, and slopes are <1%.

The experimental design was a randomized complete block with four replications. Individual plot size was 30 by 500 ft. All phases of all rotations were present every year (total = 32 plots).

After harvest of all plots in early August, residue was left standing and undisturbed throughout the fall and winter. Undercutter tillage fallow was used in the WW-UTF and WW-SW-UTF rotations in mid-May to mid-June. A Haybuster undercutter with a wide, narrow pitch, overlapping sweep blades on two ranks was used for primary spring tillage plus simultaneous injection of liquid N and S fertilizer. The undercutter sweep blades were operated at approximately a 5-inch depth. The undercutter method is considered a best management conservation practice for primary spring tillage during fallow because it breaks soil capillary continuity to effectively retain soil moisture during the dry summer while leaving most residue on the soil surface and does not pulverize surface clods. One, and sometimes two, rotary rod weeding operations (also noninversion) were conducted at 3-to 4-inch depth during late spring and/or summer to control broadleaf weeds.

No-till fallow was used in the WT-SW-NTF rotation. The soil in these plots had been in no-till with no soil disturbance except for sowing of crops since 1997. Herbicide was applied three to four times from March through August of the fallow year. As WT was sown into NTF, liquid N and S fertilizer was stream-jetted onto established WT seedlings in late October or early November just prior to an expected substantial rain. Fertility requirements for WT and WW are similar; thus, N and S fertilizer application rates for these two crops were held constant every year with a starter fertilizer of P, Zn, and B applied in the seed row with the deep-furrow drill at sowing.

Results

Straw Weight and Stem Number of Winter Triticale vs. Winter Wheat

There were no statistical differences in the weight of dry WT straw/m² compared with three- and two-year WW. The three-year WW, however, produced a much greater quantity of dry straw than did two-year WW (Table 1). There were huge differences between WT and WW in the number of stems per square meter and individual stem weight (Table 1). Winter triticale produced an average of only 284 stems/m² compared with 486 and 398 stems/m² for three- and two-year WW, respectively. Stems of WT were much thicker and heavier than those of WW with an individual stem weight of 2.36 g for WT compared with 1.47 g for three-year WW and 1.51 g for two-year WW (Figure 3, Table 1). There were never any within-year differences in individual stem weight between three- and two-year WW, but three-year WW always produced significantly more stems per square meter than two-year WW and in the long-term average as summarized in Table 1.

 

Grain Yield of Winter Triticale and Winter Wheat

Over the nine years, WT produced 14 and 24% greater grain yield than three- and two-year WW, respectively. Winter triticale grain yield ranged from 63 to 111 bu/ac and averaged 86 bu/ac (Table 3). Grain yield averaged 75 bu/ac for three-year WW and 69 bu/ac for two-year WW. Importantly, here we express both WT and WW grain as 60 lb/bu. Winter triticale grain yield was significantly greater than either WW system in most years, and the nine-year average grain yield differences were highly significant with WT > three-year WW > two-year WW (p<.001, Table 3). The relative differences in grain yield among the three treatments did not change in dry or wet crop years.

Winter triticale produced an average of 46 kernels/spike vs. 34 kernels/spike for both three- and two-year WW (data not shown). The average 1,000-kernel weight was 44, 31, and 33 g for WT, three-year WW, and two-year WW, respectively. Thus, the higher grain yield achieved by WT was due to a greater number of kernels per spike and heavier kernel weight despite having much fewer spikes per square meter compared with the WW treatments (Figure 3).

Discussion

Triticale is widely reported to consistently produce higher grain yields compared with wheat. This held true in our study where yield differences between WT and three-year WW were highly statistically different. In addition, three-year WW achieved significantly greater average yield than two-year WW.

There are many statements in the literature that WT produces more dry straw biomass than WW, but these have been largely based on visual observations and rarely quantified. In our study, the thick WT stems that weighed 60% more than those of WW visually masked the fact that WT had far fewer stems. We consistently found no differences in the quantity of straw produced between WT and WW. This information is important because farmers in low-precipitation Mediterranean environments want and need to produce as much straw as possible.

Winter triticale grew much more rapidly than WW in late winter–early spring, flowered earlier than WW, and was ripe for harvest at least seven days earlier than WW. Below-freezing nighttime air temperatures occurred some years during flowering of WT, but frost damage was rarely observed; whereas, it is well understood that substantial plant injury and subsequent grain yield decline occurs with frosts during flowering of WW.

Some PNW dryland farmers have expressed reluctance to plant WT because its male parent is cereal rye whose seed can lay dormant in/on the soil for several years. Such “feral” cereal rye and WT are somewhat similar in appearance, and both grow ≥ 4 inches taller than semi-dwarf WW; therefore, volunteer plants are easily seen in a WW field. However, importantly, unlike cereal rye, triticale seed has little to no primary dormancy, and like wheat, does not persist in the seed bank. Thus, the concern of some farmers that WT will become a feral weed is unfounded.

The early maturity of WT is favorably viewed by dryland farmers in east-central Washington as it allows for its harvest before WW. Farms are large and many farmers own or rent two or three combines. As the region is almost exclusively in two-year WW-F, including WT on some farmland acres would spread the optimum period for grain harvest over a longer time window, which would likely allow some farmers to reduce the number of combines needed.

Although WT produced an average of 14 and 24% greater grain yield than three- and two-year WW, respectively, it was not economically competitive with either WW system, primarily since it fetched a considerably lower market price. Equal profitability could be attained by 11–16% higher WT price or 11–16% higher WT yield or a combination of price and yield increases.

The SW phase of the three-year rotations is not as profitable as the WT or WW phase of these rotations. While the cost of SW production is similar to that of WW, the annualized cost for WW, including the cost of fallow, is lower than the cost of SW production while the annualized yield for WW is higher than for SW. However, the lack of profitability for SW is partially offset by the rotational yield benefits to the WW phase of the WW-SW-UTF rotation. As a result, net returns for WW-UTF were not significantly different from net returns for WW-SW-UTF.

Conclusion

Winter triticale is an easy-to-grow and hardy crop that produced significantly greater grain yield than WW. Spring wheat grain yield was slightly, but significantly, greater after WT versus after WW. Unlike essentially all reports to the contrary, WT did not produce greater dry straw biomass than WW. The WT rotation was less profitable than the WW rotations due to the lower price of WT. Additional yield improvements or development of higher-value uses for WT that increase the price of WT relative to wheat would help WT be economically competitive with WW rotations. This may be feasible in future years due, for example, to recent promising research with selected 1R chromosomes and known wheat alleles to improve protein, hardness, and gluten strength of triticale grain for bread making.