Rice in a Different Light
How does a rice plant in the field compete against the weeds growing next to it?
Rice feeds more than half of the world’s human population. As a consequence of climate change, it is becoming more and more difficult to grow rice in wet conditions in a large part of rice farming areas. Weeds, traditionally suppressed by standing water, are becoming a major problem in dry rice farming, which results in excessive use of herbicides. In urgent need for sustainable weed-control, Dr. Martina Huber investigated how rice shoot architecture could be optimized for weed suppression. She explored the natural diversity of rice varieties and defined which traits make them more competitive against weeds, by over-gowing and shading them. Rice plants with a fast and bushy growth and a shoot architecture in which leaves are arranged covering the largest possible ground cover, were selected as promising varieties.
Insights from her studies can now be used for future rice-breeding and will help to reduce the amount of herbicide usage and enable a more sustainable and climate-change resilient rice-farming.
Read the doctoral thesis of Dr. Martina Huber at the Utrecht University Repository or by clicking here.
This work is part of a collaboration between photographers Jasper Zijlstra & Jeroen Verschoor and the Plant-Environment Signaling Group of Utrecht University. Since 2022 Zijlstra & Verschoor have been photographing the role that light plays in the research group, in an attempt to make their research more accessible for the general public.
42 rice plants receiving Far-red light treatment
Far-red light is invisible to the human eye, but not so for plants. Exactly this light is perceived by plants as important information about their surroundings and neighboring plants. Far-red light is known to be a signal for plants for dense vegetation, to which the plants react by changing their growth. Exposing rice plants to far-red light enables Dr. Huber to investigate how they would react to dense-weedy conditions in the field. Usually plants respond with strong elongation and reduced formation of leaves, yet Dr. Huber observed that the rice plants were growing much faster and bushier under far-red light. Measurements proved that photosynthetic activity was almost doubled, where to date, it was thought that plants cannot use far-red light efficiently for photosynthesis.
To create these photographs, a DSLR-camera was adapted to enable it to photograph using only far-red light, with which the 42 plants receiving far-red light treatment were captured.
From seed to four weeks growth of seven rice varieties
Starting from a minuscule seed, the first leaf emerges. This receives light, which gives the plant energy to form another leaf. A cycle of collecting energy from sunlight and forming more leaves starts, following a precise pattern and rhythm dictated by an invisible code. During this cycle, the plant responds to its surroundings, in particular by different wavelengths of the light. Far-red light, perceived as the signal for dense vegetation, results in altered architecture and formation of new leaves. This response differs between varieties, each equipped with a unique code.
All rice plants that were used in the experiment were portrayed to document their growth over the course of four weeks. Seven rice varieties, each having six plants in the treatment group and six plants in the control group, were momentarily transported to a photo studio and put in the spotlight.
Rice varieties differ in the area they are shading
Even a grassy plant like rice, with its thin and long leaves, has the potential to extend and cover a big area. Being bigger and bushier than neighboring plants gives the plant a natural advantage: it provides the plant with more sunlight and therefore stronger growth, and in addition depriving competing weeds from sunlight, serving as a natural weed suppression.
These images are photograms, a technique as old as photography itself. By putting the four week old rice plants directly on light-sensitive paper and exposing it to light, a direct photographic imprint was created of the shading of each rice variety used in the experiment.