December 1995
U of M Varietal
Trials for 1995 Small Grains
Hard Red Spring
Wheat
By R.H., Busch, J.J. Wiersma, and E.A. Oelke
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Prairie Grains is the
official publication of
the Minnesota
Association of
Wheat Growers,
North Dakota Grain
Growers Association,
South Dakota Wheat,
Inc., and the
Minnesota Barley
Growers Association.
The 1995 growing season was no table because of the potential scab problems and severe heat. Scab was present in production fields throughout the west central and northwestern part of the state but may have caused most yield reduction in the northern part of the state. The average yield for the northern locations (Crookston and Roseau) was 43 bushels per acre in 1995. This compares to an average yield of 37 bushels per acre in 1993 and 1994. The southern locations’ (St. Paul, Morris, and Waseca) average yield was 57 bushels per acre. In 1993 and 1994, the average yield across these locations was 38 and 51 bushels per acre, respectively.
Table A presents the average grain yield from trials in the north, the south and statewide in 1995. In addition, the three-year (1993-95) average yields are presented, which are probably more indicative of the potential performance than one-year averages. Similarly, averages across multiple environments provide a better estimate of mean performance.
The Least Significant Difference or LSD figure near the bottom of Table A is a statistical method to determine whether the observed yield difference between two varieties is due to genetic differences in the varieties, or to interactions with other causes such as disease or soil variability. If the yield difference between two varieties equals or exceeds the LSD value, the higher yielding variety was indeed superior in yield. If the difference is less, the yield difference was probably due to environmental interactions rather than genetic differences.
LSD 5% means that with 95% confidence the observed difference is a true difference. In the past three years, the yield trials have experienced moderate to severe levels of scab. This has resulted in performance data for yield and test weight which do not reflect the true yield potentials under non-scab conditions.
Among the highest yielding varieties in the south in 1995 were 2375, Russ, and Hamer. Eleven varieties in the south were similar in yield based on the LSD 5% of 7 bushels per acre. In the north, the varieties yielded from 39 to 48 bushels per acre, which are all within the range of the LSD 5% of 9 bushels per acre. The variability of the varietal performance across environments, due to different stress factors (disease, heat, moisture), resulted in the inability to distinguish differences among varieties for grain yield in 1995.
Varieties yielding from 39 to 43 bushels per acre in the south over three years (1993-95) were similar in yield. In the north, the varieties which yielded from 52 to 57 bushels per acre did not differ over three years (1993-95). Certainly, varietal choices are not simply a function of yield performance. Other characteristics need to be considered when selecting varieties.
Varietal characteristics are presented in Table B. All values are three year averages (1993-95), except for the scab values which are based on 1994 and 1995 data. The foliar disease rating is based on data from North Dakota State University trials. The foliar disease rating is based on a complex of leaf diseases, including Septoria, tan spot, and bacterial diseases. The rating does not differentiate among these different diseases.
Therefore, the rating should be used with caution for selecting varieties and only be an aid for areas or fields where these diseases historically have been a problem.
The varietal response to scab is presented as a severity rating similar to the rating for leaf and stem rust. In addition, a second rating is presented to characterize the ability of a variety to maintain its kemels under moderate disease pressure. Our experience has been that there are several genetic mechanisms with different modes of action present in the current varieties. To differentiate between these mechanisms has been difficult. In 1995, two scab screening and evaluation nurseries were used. In addition to St. Paul, a nursery was initiated at Morris. High levels of disease pressure were present in both nurseries.
Except for Norm and Wheaton, which were used as scab susceptible checks, none of the older varieties which tested susceptible to scab were included in the variety trials. These susceptible varieties are listed in Table C. These varieties should only be grown with extreme caution, knowing that under even light to moderate disease pressure for scab, significant reductions in yield and test weight can result. Following is a short description and comparison of new varieties.
Variety selections for 1996 should be a function of yield, disease responses and quality parameters. Two of the predominant varieties in the state, namely 2375 and Grandin, are susceptible to the leaf diseases Septoria and tan spot. In addition to a susceptibility to Septoria and tan spot, 2375 has a lower yield potential and can have problems with shattering, lodging, and weed competition in the northern part of the state. However, 2375 has the best tolerance to scab.
Several new varieties have been released in the past two years. The University of Minnesota released Verde, NDSU released Trenton and Kulm, and SDSU released Russ. AgriPro released three new varieties: Hamer, Lars, and Norlander. Under light to moderate scab disease pressure, these new releases with the exception of Trenton and Norlander are good alternatives to 2375, since yield potential and agronomic performance are often superior to 2375 in the northern part of the state. Except for Trenton, which will be increased for certified seed next year, dealers should have enough certified seed for at least 50,000 acres of each of these new varieties.
1) Verde is a medium late maturing variety from the University of Minnesota with high yield potential. Verde is a semi-dwarf variety with good resistance to lodging, similar to Norlander and Lars. Verde is moderately resistant to leaf rust and resistant to stem rust. Verde is moderately susceptible to scab but maintains above average yield test weight. Insufficient data was available to provide a reliable foliar disease rating, but Verde possesses good green leaf retention. Verde has a medium test weight, similar to Hamer and 2370, and intermediate grain protein percentage, lower than Russ but higher than Hamer. The milling and baking quality is intermediate, similar to 2375 and Russ.
2) Trenton is a new, early maturing variety from NDSU with a medium to high yield potential. Trenton has standard height and is susceptible to lodging, similar to Sharp and Butte 86. Trenton is moderately resistance to leaf rust and resistant to stem rust, but is moderately susceptible to the foliar disease complex. Trenton is susceptible to scab but maintains yield and test weight. Trenton has an above-average test weight, heavier than Stoa but less than Sharp, and medium-
high grain protein percentage, but less than Grandin or Kuhn. The milling and baking quality is high to medium, similar to Kulm. NDSU has recommended the variety for the western and central part of North Dakota.
3) Kulm was released by NDSU in 1994. Kulm is a standard height variety and susceptible to lodging, similar to Butte 86. Kulm is early maturing, similar to Sharp, and has a high yield potential. Kulm is moderately resistant to leaf rust and resistant to stem rust, but susceptible to the foliar disease complex, including Septoria and tan spot. Kulm is moderately susceptible to scab. Kulm has a medium to high test weight, similar to Grandin, and a high protein content; lower than Grandin but higher than Stoa. The milling and baking quality is high to medium; lower than Grandin but higher than Butte 86.
4) Russ is a new, early maturing variety from South Dakota State University with high yield potential. Russ is a standard height variety and susceptible to lodging, similar to Sharp and Stoa. Russ is moderately resistant to leaf rust and moderately resistant to stem rust. Russ is moderately susceptible to scab. Insufficient data was available to provide a reliable foliar disease rating. Russ has a medium test weight, similar to Marshall but slightly lower than Butte 86, and intermediate grain protein, similar to 2370. The milling and baking quality is intermediate, similar to 2370 and 2375.
5) Hamer is a semi-dwarf variety from AgriPro with excellent resistance to lodging, similar to Marshall. Hamer has a high yield potential while its maturity ranks as medium early, similar to Trenton and in between varieties 2375 and Norm. Hamer is moderately resistant to leaf rust, resistant to stem rust, and moderately resistant to the foliar disease complex, similar to Norm. Hamer is moderately susceptible to scab. Hamer has a medium test weight, similar to 2370 and Verde, and intermediate grain protein percentage. The milling and baking quality is medium to low, similar to Marshall.
6) Lars is a semi-dwarf variety from AgriPro derived from the same cross as Hamer. Lars has good resistant to lodging, similar to Norm and Verde. Lars is high yielding and is medium late to late in maturity, similar to Norm and Stoa. Lars is moderately resistant to leaf rust, resistant to stem rust, and moderately resistant to the foliar disease complex, similar to Norm. Lars is moderately susceptible to scab. Lars has a medium low test weight and a medium low grain protein percentage. The milling and baking quality is medium to low, similar to Marshall.
7) Norlander is semi-dwarf variety from AgriPro with good resistance to lodging, similar to Verde and Norm. Norlander has a high yield potential with early maturity, similar to Kulm and Sharp. Norlander is moderately resistant to leaf rust, moderately susceptible to stem rust, and moderately resistant to the foliar disease complex except for tan spot, for which it is moderately susceptible. Norlander is susceptible to scab. Norlander has a medium low test weight and an intermediate grain protein percentage, similar to Russ and 2370. The milling and baking quality is intermediate, similar to 2375 and Verde.