Effects of substrate acidity and UV-B radiation on photosynthesis of radishes

Abstract

The aim of this study was to assess the combined effect of substrate acidity (pH 4.8; pH 3.8) and 1 kJm−2d−1 UV-B radiation on photosynthesis and growth of radishes (Raphanus sativus L.). Radishes were sown in a neutral pH 6.5 peat substrate. When the second true leaf unfolded, the growth substrate was acidified using different concentration of H2SO4 and exposed to UV-B radiation for a period of ten days. Gas exchange parameters were measured with the LI-6400 portable photosynthesis system. Content of chlorophyll was evaluated spectrophotometrically. The results showed that the greatest inhibition of net photosynthesis was observed when radishes were grown in an acidified pH 3.8 substrate. The decrease of the photosynthesis of radish plants treated with both investigated factors (substrate acidity and UV-B) were lower compared to the effect of substrate acidity alone. UV-B radiation stimulated both enzymatic reactions of photosynthesis and water use efficiency of radish plants grown in acidified peat substrates. Also, investigated factors had higher impact on biomass of tuber than biomass of foliage.

Light Intensity Influence on Growth and Photosynthetic Characteristics of Horsfieldia hainanensis

“…The Ci size depends on four factors: the CO 2 concentration of the air around the leaves, Gs, mesophyll conductance (gm), and the photosynthetic activity of the mesophyll cells (Januskaitiene, 2011). Gs represents the degree of stomatal opening, which is the primary factor affecting plant photosynthesis and respiration, with a direct impact on transpiration (Kinose et al, 2020;Zhen and Bruce, 2020).…”

The effect of foliar spray fertilizers on the tolerance of Hordeum vulgare to UV-B radiation and drought stress

“…Biophysical processes, which include CO 2 transport through the leaf and stomata, and biochemical processes located in the chloroplast thylakoid membranes, stroma, mitochondria and the cytosol of the cell, determine the net rate of CO 2 assimilation. Whereas the increase in intercellular CO 2 level (in well-watered plants and treated with UV-B radiation) also indicates that net photosynthesis is reduced by reducing CO 2 fixation by Rubisco, and can also include conditions in which enzymes of the Calvin cycle (other than Rubisco) limit the rate of photosynthesis (Januskaitiene 2011). Barley plants exposed to UV-B show both a decreased photosynthetic rate and increased intercellular CO 2 concentration.…”

Low UV-B radiation and substrate acidity impact on photosynthetic parameters of Brassica napus

“…When 2nd true leaf unfolded, i. e. at leaf development stage (BBCH-12) [21] rape plants were divided into four groups: I) reference treatment group (substrate pH 6.5) was watered with distillated water all the time; II) rape plants were exposed to 1 kJm -2 d -1 UV-B radiation; III) growth substrate of rape plants was watered with 0.07 M concentration H 2 SO 4 solution and growth substrate acidified till pH 4.8; IV) plants growth substrate was acidified as mentioned above till pH 4.8 and rape plants exposed to 1 kJm -2 d -1 UV-B radiation. The treatment variants were chosen according to earlier experiments at the Environmental Department of the VMU [20]. Duration of the experiment was five days.…”

“…While our earlier experiments with radish showed a slightly different plant response to combined effect of the mentioned stressors, i. e. the decrease of photosynthesis of radish plants treated with substrate acidity and UV-B radiation was lower compared to the single impact of the substrate acidity. And UV-B radiation stimulated both enzymatic reactions of photosynthesis and water use efficiency of radish plants grown in acidified peat substrates [20]. So this study focused on the combined impact of low UV-B radiation and substrate acidity on photosynthesis and growth of summer rape (Brassica napus) plants.…”