In late February, in an almond orchard in the Sacramento Valley, the fall-planted cover crop mix of grasses, brassicas and legumes had barely produced a green fuzz above the soil surface, and it was unclear when it would...
Ozone reduces plant growth, yield of horticultural and agronomic products, and beauty of ornamental vegetation. But the mechanism of ozone damage is not well understood. As a result, methods to protect plants are not available.
The Air Quality Effects Laboratory, in collaboration with other researchers in California, other states, and other countries, is working to understand the mechanism of ozone damage, to develop production methods to protect crops, and to identify targets for genetic improvement of plants.
It is well known that photosynthesis is damaged by ozone. It is less clear that this is the only or even the primary target of ozone action. Loading of newly photosynthesized sugars into the phloem for long distance translocation to roots and fruits is rapidly inhibited. Allocation of biomass among competing plant parts is disrupted by ozone, reducing root development and hydraulic conductance, and indirectly affecting leaf water relations and photosynthetic gas exchange. The Air Quality Effects Laboratory has shown that in Pima cotton (Gossypium barbadense) carbohydrate translocation is inhibited more than photosynthetic carbon assimilation following brief exposures to high concentrations of ozone.