biologia plantarum

Biologia plantarum 67:28-35, 2023 | DOI: 10.32615/bp.2022.039

Cucumber leaf necrosis caused by radiation with abrupt increase of far-red component

T. SHIBUYA^{1, *}, C. KATAOKA², K. NISHIO², R. ENDO¹, Y. KITAYA³, Y. SHINTO², K.I. MISHIBA⁴, Y. IWATA²

¹ Graduate School of Agriculture, Osaka Metropolitan University, Osaka 599-8531, Japan

² School of Life and Environmental Sciences, Osaka Prefecture University, Osaka 599-8531, Japan

³ R&D Center for the Plant Factory, Osaka Metropolitan University, Osaka 599-8531, Japan

⁴ Faculty of Agriculture, Ryukoku University, Otsu 520-2194, Japan

Plants exhibit morphological plasticity in response to changes in the proportion of far-red radiation (FR). However, little is known about the response to a sudden increase of FR component. Cucumber seedlings were acclimatized to radiation without FR (FR-) for 1 - 5 d after germination, and then transferred to radiation containing FR (FR+) at levels similar to those in natural sunlight. Other seedlings were acclimatized to FR- or FR+, which was maintained continuously. The sudden increase in FR damaged the cotyledons and the first true leaf, especially when radiation was changed from FR- to FR+ at days 3 or 4 after germination. Necrosis of the damaged leaves may have resulted from inhibition of water flow in leaf xylem, because wilting and decreased stomatal conductance were observed simultaneously with leaf necrosis. Plants in the treatment groups that showed the most frequent damage showed two peaks in cotyledon elongation. This suggests that the leaves that had been acclimatized to FR- were easily damaged by the sudden promotion of leaf expansion caused by FR+.

Keywords: leaf expansion, morphological plasticity, phytochrome, radiation quality.

Received: May 18, 2022; Revised: September 8, 2022; Accepted: October 14, 2022; Published online: February 22, 2023  Show citation