Plant roots proven to actively adapt to unreliable resources
Have you ever accidentally killed a plant, watering it too much, or too little? Giving it the wrong amount of sunlight, or planting it in the wrong soil? People often feel guilty about subjecting plants to this kind of treatment, since the plants are completely dependent on us, like innocent babes in the (potentially over-watered) woods. Two recent studies suggest that you may not have had such complete control over your plants as you thought, as multiple species have been found to employ different growth strategies in response to their environment. While nobody is suggesting your drooping daisies are cognizant of your poor gardening, there’s a chance they’re actively adapting to make the most of harsh conditions.
Peas play the odds
The first study looked at how risk-averse pea plants are. This may sound wildly outside the behavior patterns of your average greens, but it was demonstrated in how much the plant developed different root structures in different conditions. Plants had their roots separated into two adjacent pots, each with differing amounts of nutrients. In general, the plants grew more robust roots in the pot with more nutrients, which intuitively makes sense, almost like flowers that grow tilted towards their local light source. However, the plants showed more complex degrees of responsiveness when the nutrients were not consistently supplied.
In a second phase of the experiment, researchers started actively manipulating the amount of nutrition available in each pot to see if the peas could respond to the shift in resources. If one pot offered a minimum amount of nutrition at all times, but the other offered a fluctuating amount of food, from huge spikes to nearly nothing, the plants seemed to “choose” the less predictable pot, growing more roots in that direction. If the stable pot offered a more comfortable amount of nutrients at all times, the plants seemed to rely on it more often, gambling on the fluctuating flower pot less. It’s not yet clear what physiological process triggers these shifts in growth, but at the very least it shows that plant growth is more active and dynamic than previously understood.
Grass roots restrict themselves
Along those lines, grass has been found to adjust root growth according to the amount of water available. Grasses employ various roots, with a central “crown root” that acts as the plant’s primary conduit for water and nutrients from the soil. Researchers found that if the available water is reduced, such as during a drought, that grasses seem to voluntarily slow their crown root growth, putting themselves on a stricter water budget until more moisture is available. While the family of plants studied includes maize, sorghum, and sugarcane, this kind of hydraulic belt-tightening was much less pronounced in domesticated breeds. If farmers want to incorporate these plants’ natural drought-resistance measures, they may have to make adjustments in their crops’ breeding.
Both studies may have applications in how we grow plants for food and/or fuel. Working with a plant’s natural adaptions, or trying to encourage them further, may help us make the most of harsh growing conditions as demand for food continues to rise around the world. It may also make you feel even worse about that orchid you killed when you realize that the flower may have been actively struggling to survive your poor gardening. Better luck next time?
Source: Pea plants demonstrate ability to 'gamble' -- a first in plants by University of Oxford, EurekAlert!