Conduct Your Own Variety Trials - Heather Jerrett, High Mowing Organic Seeds Trials Manager
Evaluating the performance
of different varieties through trialing is an important tool for farmers
and gardeners. Choosing the right varieties for your specific area and
field conditions can significantly reduce stress and increase success
while avoiding the disappointment of a failed crop. At High Mowing’s
trial fields, we evaluate hundreds of varieties and use this information
to select the best overall varieties to offer our customers.
Planning the Trial
are some key tips to planning your trial. First, you want to prioritize
the crops you would like to trial. It may sound appealing to trial many
crops, but in reality this will likely lead to more work than you can
keep up with and you won’t be able to acquire the information to make it
worth your labor. It is good to start off with one or two crops that
are most important to you or that you would like to introduce into your
mix. If you are able to plan a few years out you will have all the more
time to talk to fellow growers, take notes from various catalogs, and
look up relevant information before the plants are actually in the
field. In the HMS trials we have a priority list. More often than not,
we aren’t able to get to everything, so this way everyone knows which
trials to pay especially close attention to and which ones are important
but can be left behind for a bit.
Now that you have a plan of what you would like to trial,
it is time to write down some goals. It is important to write out your
goals so that when you are choosing varieties, sourcing seed and
planning the trial, your efforts will reflect your goal. Variety trials
require time and attention. If you can take the time to set up a
well-planned trial you will spend less time figuring it out during your
busy season. The trial goals should determine the timing of planting,
managing the crop, how large the plot size needs to be, when and how to
evaluate the crop and how the evaluation will be interpreted.
Choose Varieties and Acquire Seeds
The next step is choosing varieties and acquiring seed.
This will be very dependent on the goals of your trial. If you are
trying to find the best variety of spinach for over-wintering you will
want to check in with growers that are already over-wintering spinach
and get some recommendations and perhaps add a few of your favorite
varieties as well as varieties suggested in catalogs. A helpful tip is
to create a wish list of desired characteristics. This will help guide
your variety selection. The list of desired traits will also help define
what you would like to evaluate later. If you are trying to identify
the earliest ripening orange slicing tomato you may also want to
describe your goal as finding an orange slicing tomato that ripens in
less than 80 days in the field, weight averages 8-10oz, determinate to
semi-determinate habit, sweet flavor, and is resistant to Fusarium and
An important task when choosing your varieties is to
include a market standard or a variety that you are already very
familiar with. This variety will act as a point of reference and the
standard for one or more of your desired traits. With so many unknown
environmental factors, it is important to be able to compare the
progress of unknown varieties to one that you know well.
Types of Trials
There are two basic types of trials: observational trial
and replicated. In an observational trial, you have a single plot of
varieties to observe. A replicated trial, on the other hand, involves
replicating the single plot in multiple areas on your farm or garden.
The replicated trial requires more attention and effort and may not be
necessary for your goals. For simplicity we will complete this review
with the observational trial in mind.
Observational trials work great for an initial evaluation
of variety characteristics or particular strains of the same variety,
checking for trueness of type or seed quality concerns such as
germination rate or emergence vigor, identifying variety traits and
potential strengths and weaknesses of them.
When performing observational trials you only have one shot
for the season to look at your set of varieties. It is important to
reduce any variation in your plot such as soil type, sun exposure,
access to irrigation, slope. If you are unable to eliminate plot
variation, it is important to keep these limitations in mind. For
example, in 2010 we conducted an extensive spinach trial. We could
clearly see variability in fertility where the compost had been spread.
Because it was consistent throughout the plot we were evaluating, we
were able to accurately compare varieties. However, we also had to keep
in mind that each variety was not living up to its true potential.
The number of plants you will want to include in your trial
depends on the available space, and, to a large extent, on the crop
type and the number of varieties you would like to include. The greater
the population size the more reliable your information will be.
A very important task when pulling your trial together is
labeling. From the greenhouse to the field you will want to label every
variety and its source. At High Mowing, we label everything twice, just
in case one gets lost. We also usually put varieties in alphabetical
order to make it easy to find them in the field. You may also do a blind
trial where you take all your varieties and assign them a number. From
then on, each variety is only associated with a number. Blind variety
trials eliminate any bias you may have towards your long-time favorite
or ones you think are more disease resistant because of the claims on
the packet and so on.
The trial evaluation should reflect all the characteristics
stated in your goal and should be a combination of data and notes. Data
can be very useful but is also time consuming. Narrow your data
objectives to a manageable list that reflect your desired
characteristics. At High Mowing, we use a number of evaluations based on
the nature of the trial such as: germination rate, emergence, vigor,
plant characteristics (height, weight, sensitivity to bolting), edible
portion of plant characteristics, uniformity, flavor, ease of
harvesting, length of productivity (first to final harvest dates),
yield, holding ability in the field, packing, washing, storage ability
and pest and disease sensitivity.
Evaluation criteria can be qualitative or quantitative.
Quantitative data can be measured directly (height of plant, weight of
fruit etc). When taking quantitative data, it is helpful to have
multiple measurements per plant or fruit, and take an average so that it
represents a wide range instead of just one unit. Qualitative traits
are descriptive - such as color, flavor and uniformity. We measure
these with a 1-5 ranking, where 1=worst and 5=best. It is important to
use the full range when using a ranked scale. This can prove difficult
especially if all your plants look great. Start out with obvious
evaluations like color, or growth rate, to get used to the ranking
process and move onto vigor, disease resistance or overall best. I like
to walk through and find my #1 ranking and my #5 ranking, and then fill
in the spaces between. If you feel the ranking system is too complicated
or does not offering good information, you can also use a rating system
where #1 could equal a certain quality and #5 another quality. The
rating system does not offer good comparative data to crunch, but may be
sufficient for your needs. I often use a rating system for things like
maturity, where 1=no signs of maturity, 3=perfect maturity and 5=over
mature. The most important role of data collection is that you can
easily use it.
Assess Your Results
Once all data and field notes are collected it is time to
assess your results. This is probably one of the most painful steps for
me because I already have all the results in my head and feel like I
have a good assessment of varieties from seeing them in the field. But
as you would guess, there are often hidden surprises in the numbers and I
am always thankful I have taken the time to write up my conclusions. It
also makes it very easy to return to for information and for others to
be able to get a quick snapshot. Again, you will want to start with your
goal and start reviewing each characteristic one by one. Much can be
learned by simply looking over the data without using statistical
analysis. However, statistics offer a relevance to the data you
collected and can provide insight to the variability of the data. We
have performed statistical analysis in the past but do not feel it is
necessary for our purposes at this point in time. We take all of our
data and enter it into Excel datasheets. This proves to be very helpful
when reviewing our data, especially to easily calculate what the average
ratings are for criteria. This allows you to state whether a variety is
above or below the average immediately.
The last and most helpful step is to identify the winners
of your trial. At the end, when I have all the information in front of
me, I like to give each variety and overall ranking based on data and my
notes. This quickly lets me see which varieties performed well based on
my desired characteristics and I can include notes on how to proceed in
the future or other characteristics that have caught my eye.
I hope all of the above gives you a good starting point to
trial some varieties on your farm and develop a process for assessing
which varieties are truly standing-out.