Fall has arrived, and for many crops, this means that it is harvest season. For small grains, however, the season starts anew. The UC Davis small grains variety evaluations are conducted across the state, including a site in the Delta. The results of last year's evaluations are now available, and we invite you to take a look as you prepare to plant your new crop. 

All of the 2017 trial results are available from this webpage. It is a rich dataset, so allow me to highlight a few things. We evaluated 43 varieties of common wheat and 9 varieties of triticale over 4 replicate blocks at the Delta site. Delta site data and data from other statewide sites are available from the link “single site data” for common wheat and triticale. When viewing the single site data, keep a few things in mind. The data show what varieties performed well under specific conditions. For example, the Delta evaluation was conducted on a Rindge muck soil, which according to soil maps, has about 30 percent organic matter in the top foot of soil. Additionally, the site received approximately 37 inches of rain, and there was standing water for much of the growing season. Under these conditions, the varieties that yielded best were late-maturing varieties. This is visualized in Figure 1, which shows a “heat map” of the yield results by location. Higher yields are represented as blue, and lower yields are represented as red.

To understand trends over time, we suggest reviewing the 3-year summaries, which are available from the link “Yield and Protein Summary” for common wheat and triticale. These summaries indicate which varieties performed consistently well over time. For these summaries, the Delta is grouped with other Sacramento Valley locations. The data indicated that the varieties performed similarly between the Sacramento Valley and the Delta, compared to the San Joaquin Valley and the Delta. This is probably due to similar climatic considerations, like rainfall and temperature. The 3-year summaries rank the varieties for both yield and protein. In the future, rather than tables, the research team will develop an online tool to assist with variety selection that will take both yield and protein into account. Stay tuned for more information on this tool.

Keep in mind that disease ratings are important considerations. Disease ratings are found here, where “S” indicates susceptible varieties and “R” indicates resistant ones. Additionally, some of these varieties are in initial stages of testing, so not all of them are commercially available. Look for whether the variety is “released”, which is indicated on the data tables.

Barley and durum wheat were also evaluated at certain locations but not in the Delta. We will continue trialing small grain varieties in the Delta in 2018.

The 2017 UCCE grain corn variety trial was planted on May 9^th, almost two weeks later than the trial was planted in 2016, due to the wet winter and spring. The trial is located in the Sacramento County Delta. Three replicate blocks of fifteen varieties were planted by air planter. This year, the varieties represent both conventional and RR varieties, as indicated in Table 1. Stand counts were made approximately two weeks after planting, and bloom was assessed over the week of July 10^th. While bloom occurred later this year due to the later planting, the number of days to bloom was less than in 2016. Across all varieties, the average number of days to bloom was 65, compared to 70 in 2016. Over the remainder of the season, we will also evaluate disease pressure (fusarium ear rot, head smut, and common smut), lodging, ear height, grain moisture, and yield. Results from previous years are available from my website. 

Table 1. Corn varieties planted in the 2017 UCCE grain corn variety trial.

 

Table 1 shows the results of the 2016 UCCE Delta field corn variety trial, located on Tyler Island. Three replicate blocks of eighteen varieties were planted on April 27^th by air planter. The eighteen varieties included 16 varieties submitted by seed companies and two varieties submitted by the grower. All varieties supplied by the seed companies were glyphosate-tolerant varieties. Each plot consisted of four 30-inch beds on an average row length of 1158 feet. Seed was planted approximately two inches deep and six inches apart down the row. The soil is a Rindge mucky silt loam with approximately 20 percent organic matter in the top 15 inches of soil. The Rindge series is a mucky peat soil down to about 60 inches, and approximately 55,600 acres in the Delta are described by the Rindge classification. The previous crop in the field was wheat. Subsurface irrigation by “spud ditch” was employed three times. Nitrogen was applied preplant (125 units/acre as NH₃), and 34 gallons/acre of 8-24-6 with ½% of zinc was knifed in at planting. Weed control was by cultivation and herbicide application (Steadfast, Shark, and No Foam A adjuvant). Zeal miticide was applied. The field was harvested on October 10^th.

The table presents mean values for the three replicates. When interpreting the results, keep the following in mind. The mean is equal to the sum of values divided by the number of values, in this case, three replicates. The statistical method used to compare the means, called Tukey's range test, compares all means against each other. Varieties were considered statistically different if their P value was less than 0.05, or 5 percent. What this means is that when differences between varieties exist, we are 95% certain that the two varieties are actually different; the results are not due to random chance. Differences between varieties are indicated by different letters following the mean. For example, a variety that has only the letter “a” after the mean yield value is different from a variety that is followed by only the letter “b”, but it is not different from a variety whose mean value is followed by both letters (“ab”). Similarly, a variety whose mean yield is followed by the letters “ab” is not different from a variety whose mean yield is followed by the letters “bc”. Seven varieties have a letter “a” following their mean yield, which means that those seven varieties all performed similarly in the trial. The numerical values of these seven varieties differ, but based on this research, we cannot attribute those numerical differences to variety differences. Among varieties, there were also differences in stand count, bloom date, fusarium ear rot presence, ear height, grain moisture, and bushel weight.

The CV, or coefficient of variation, is the standard deviation divided by the mean, or a measure of variability in relation to the mean. For some measures, particularly the disease percentage, the variability between the three replicates was very high.

Special thanks go to grower cooperators, Steve and Gary Mello, and participating seed companies. The report is available in an easy-to-print version from my website.

 

Tables 1 and 2, respectively, show the results of the 2015 San Joaquin County rice variety trial and a 5-year yield summary of very early maturing commercial varieties. The statewide trials are a cooperative effort of the California Cooperative Rice Research Foundation, Inc., the United States Department of Agriculture, and the University of California. The trials compare advanced breeding lines with commercial varieties. The San Joaquin County test site is located in the Delta. It is a test site for very early maturing varieties because San Joaquin County is cooler than other rice growing regions of the state. The varieties were drill-seeded on April 29^th at a rate of 140 lbs/acre and harvested on October 13^th.

When interpreting the results, consider the following. The mean represents the average of all varieties. The CV, or coefficient of variation, is a measure of variability of the data in relation to the mean. The LSD (.05), or least significant difference at 95%, is used to compare means of different varieties. When the difference between two varieties exceeds the LSD value, we are 95% certain that the two varieties performed differently; the results are not due to random chance. For example, the LSD of the grain yield at 14 percent moisture is 640. This means that if the yields of two varieties differ by at least 640 lbs/acre, then we can conclude that the two varieties yielded differently. In this case, the top six varieties in Table 1 had statistically similar yields. In Table 2, yield means are averaged across all locations and years and compared to M-104, a standard very early variety. Over the five years, and across the four very early variety locations, M-206 – a common variety in this area – yielded 2.2 percent higher than M-104.