Prior to this study in California Central Valley ( non-attainment for ozone and PM), crops cultivated on the valley floor, potentially a large source of monoterpenes, sesqui terpenes, and other biogenic emissions, had not been extensively studied. In phase I, biogenic emissions at the branch or whole plant scale were characterized for more than 20 key crop species in a greenhouse. All crops studied had very low emission rates of isoprene. These results are consistent with previous studies in California for several of the same crop species. All crops studied, with the exception of orange, fall in the category of low mono terpene emitters. The ‘Parent Navel’ orange tree emitted more terpenes than other crop plants though emissions from orange are still far less than emissions from the major biogenic emitting California plant species occurring in the natural environment.
In phase II, canopy scale flux measurements were performed at the selected citrus orchard site for a full year. During flowering, harvesting, and pruning, emissions increased substantially for short periods. Continuous biogenic measurements were made during two specific study periods including a summer period and a flowering period to assess the emission contributions at different times of the day.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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