The photosynthetic parameters of cucumber as affected by irradiances with different red:far-red ratios

• Published in: Biologia Plantarum
• Main Authors: T. Shibuya, R. Endo, T. Yuba, Y. Kitaya
• Format: Article
• Language: English
• Published: Institute of Experimental Botany of the Czech Academy of Sciences 2015-01-01
• Subjects: cucumis sativus; intrinsic water-use efficiency; rubisco; stomatal conductance; stomatal density
• Online Access: https://bp.ueb.cas.cz/artkey/bpl-201501-0025_The-photosynthetic-parameters-of-cucumber-as-affected-by-irradiances-with-different-red-far-red-rat.php
• ISSN: 1573-8264

We compared photosynthetic performance between cucumber (Cucumis sativus L.) leaves acclimated to saturating irradiances with high red: far red (R:FR = 10) and normal R:FR (= 1.4) ratios. The net photosynthetic rate (PN) and stomatal conductance (gs) of the leaves acclimated to high R:FR were greater than those of the leaves acclimated to normal R:FR; the greater gs partly explains the greater PN. The greater gs of the high-R:FR-leaves probably resulted from a higher stomatal density and/or a greater size. PN of the high R:FR leaves was still greater than that of the normal R:FR leaves at the same intercellular CO2 concentration (ci). This indicates that non-stomatal factors also increased the photosynthetic capacity of the high R:FR leaves. The maximum Rubisco carboxylase activity estimated from a PN-ci curve analysis was also greater in the high R:FR leaves, however, the intrinsic water-use efficiency (WUEi = PN/gs) of the high R:FR leaves was lower than that of the normal R:FR leaves.