Developing Applications with Partners

We develop the application to suit the needs of our partner. Below are some applications developed in conjunction with our research partners.

Root System Development over Time

Because of the nondestructive nature of our imaging process, we can image the same plant over and over during its development.

We have done daily imaging and even morning and evening imaging to relate root growth to photo-period; that is, do the root systems grow during nighttime.

For maize, our standard imaging period is weekly. The below figure shows maize imaged at planting, after four weeks, and after another three weeks. These plants are in 200 x 500 mm containers (reduced resolution).

Characterize Root Architecture

A recent heavily cited paper by Hammer, et al. (click here) concludes that "Change in [maize] root system architecture and water capture has greater direct effect than change in canopy architecture and light capture in explaining enhanced plant growth rate and biomass accumulation associated with historical yield increase and its interaction with density; ..."

Figure 3 from that article (shown below) illustrates that a greater root angle (b) produces a relatively narrow, deep root volume. This has two advantages.

1. Closer spacing of plants allows more plants per unit of land area and thus greater yield.

2. Deeper root systems have more access to water at deeper soil strata.

In the case of rice, two varieties can be screened for root angle and depth by simply inspecting the images. The below images show two example plants of two varieties. These plants are in 50 x 200 mm containers. Red/cyan glasses are required to see the stereo effect.

Angular distribution of roots would be completely lost using the conventional wash and scan method.

Trait Screening

Periodic imaging can be an exploratory process. For example, an early establishment study may be used to characterize the early development of soybean cultivars. Below is a series of images of soybean roots at one week intervals. These plants are in 50 x 200 mm containers.

Given the knowledge of when a desired root trait becomes distinguishable, one may grow plants to that age and nondestructively image their root systems in order to determine the presence of that trait. If the trait becomes distinguishable at day 7, plants having the trait can be left to grow to maturity and plants not having the trait can be terminated. This results in a saving of grow room space, energy, time, and money.

As an example, two cultivars of soybean, one having a “prolific” root system and the other having a “normal” root system were grown and imaged.

The distinctions between the two cultivars may not be easy to see using the unaided eye. These plants are in 50 x 200 mm containers.

The two cultivars of soybean were distinguished by plotting lateral root density against taproot length.

In this case, the normal root cultivar (left image in Figure above) is below the black line and the prolific root cultivar (right image in Figure above) is above the black line. When the two varieties are crossed, this classification capability allows the screening of progeny for the prolific root characteristic at day 7. From the data plot above, it is clear that use of taproot length alone would not make a separable classification. For this reason, growing plants in glass bottomed soil pots will not reveal the difference between these two cultivars at such an early stage.

Automated Root System Analysis

When dealing with a large number of complex root systems, we can use our segmentation software to identify root and filter out noise. We then can apply further analysis to measure properties of the root system automatically

An example is the Transect Method. In this method, a series of horizontal lines, or transects, is defined at regular spacings. At each transect line, the segmented image is analyzed to determine the position, number and diameter of roots crossing that transect.

These and other derived values can be used to plot the distribution of roots within the root zone.

The below graph shows the distribution of root mass (arbitrary units) vs. depth.

The below graph shows the distribution of number of root crossings vs. depth.

The below graph shows the distribution of mean root diameter vs. depth.

Other analyses are possible; for example, curved transects, root angle at transect crossing, convex hull, and fractal dimension.

Introduction of Stressors

A plant may be subjected to stress during part or all of its development. The polymeric growth substrates used by Phenotype Screening Corporation contain no nutrients, moisture, or pests of any kind. The Plant Scientist has total control over nutrient and moisture delivery to the plant. Pests may be introduced and plant response monitored.

When subjected to iron deficiency Maize displays a chlorosis in the interveinal areas.

A soybean subjected to drought stress.