Yellow leaves for more energy

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Yellow leaves for more energy

Optimal use of photosynthetic capacity, the capture of energy is of great importance for a higher crop yield. Knowing this, it is not strange that for a long time breeders were selecting for greener leaves. As greener leaves mean more photosynthetic capacity. But this is not the whole story. Greener leaves also let through less light, putting the lower leaves in de the shade. Not ideal for optimal photosynthesis. Now researchers from the Netherlands and China showed that actual selecting on yellower leaves can result in a plants optimal energy capture.

The amount of energy a leaf in theory can capture with photosynthesis depends on the amount of chlorophyl in the leaf. The greater the amount of chlorophyl, the more sunlight it can absorb, the bigger the photosynthesis capacity. And the greener the leaf. But that is the theory. To find out how this translates to a whole plant, the researchers compared plants with more or with less chlorophyl in their leaves.

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Greener is not always automatically better

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To do this the researchers measured the photosynthesis capacity, but also things like how much light a leaf absorbs, and which proteins they made. This enabled the researchers to conclude that extra green leaves actually don’t contribute that much extra. While having less chlorophyl had a clear effect, although which depended on the background of the plant.

The researchers noticed that plants with a lower amount of chlorophyl needed less protection against an overdose of sunlight. This saved energy. When the plant manages to use this saving for making more proteins that convert the captured sunlight into glucose, then these plants, in the end captured more energy.

Yellower leaves can mean a more profitable energy balance for the plant. In this way, a reduced chlorophyl level can result in an optimal use of its photosynthetic capacity. Making greener not always automatically better.

Literature

Z. Zhou, P.C. Struik, J. Gu, P.E.L. van der Putten, Z. Wang, X. Yin, and J. Yang (2023) Enhancing leaf photosynthesis from altered chlorophyll content requires optimal partitioning of nitrogen,Crop and Environment, https://doi.org/10.1016/j.crope.2023.02.001.