Sensitivity of yellow passion fruit to ultraviolet‑B radiation

Abstract

The objective of this work was to evaluate the effects of UV‑B radiation on the vegetative growth and on the gas exchange characteristics of passion fruit plants (Passiflora edulis) grown in greenhouse. The average unweighted UV‑B radiation near the apex of the plants was 8 W m^-2 for the UV‑B treatment (high UV‑B), and 0.8 W m^-2 for the control plants (low UV‑B). Plants were irradiated with UV‑B for 7 hours per day, centered on solar noon, during 16 days. High UV‑B radiation resulted in lower shoot dry matter accumulation per plant. The content of UV‑B absorbing compounds and anthocyanins was increased in the plants exposed to high UV‑B radiation, when compared with the control. UV‑B radiation did not affect stomatal conductance or transpiration rate, but reduced photosynthesis and instantaneous water‑use efficiency, and increased intercellular CO2 concentration. The accumulation of UV‑B‑absorbing compounds and anthocyanins did not effectively shield plants from supplementary UV‑B radiation, since the growth and photosynthetic processes were significantly reduced.