Critical responses of photosynthetic efficiency in Campsis radicans (L.) Seem to soil water and light intensities

Abstract

Campsis radicans (L.) Seem is one of the main forestation tree species in semi-arid loess hilly region. Using the CIRAS-2 portable photosynthesis system, the light-response of the photosynthetic efficiency parameters of three-year-old C .radicans leaves, such as net photosynthetic rate (P N), transpiration rate (Tr), water use efficiency (WUE), and light use efficiency (LUE), were studied under different soil water conditions in order to explore the effects of soil water stress on photosynthesis and the suitable soil water content for water-saving irrigation of this liana. Soil water and light intensity needed by the growth and development of C .radicans were analyzed. The results show that P N , Tr, WUE, and LUE of the leaves had threshold value to soil water and photosynthetically-active radiation (PAR). The nonrectangular hyperbola model was used to simulate light-response curve and the convexity was about 1. With the increase of soil relative water content of field capacity (Wr, ranged from 20.1% to 71.1%), the light compensation point declined while light saturation point, the maximum P N and apparent quantum yield increased. When Wr was about 71.7%, the light compensation point was at the minimum (21.61µmol/m 2 /s) and the light saturation point was at the maximum (1400 µmol/m 2 /s). In order to maintain the normal plant growth and have higher P N , LUE, and WUE synchronously, the range of Wr was from 49.5 to 71.1%. The optimum Wr was 71.1%, and the minimum Wr was 28.2% for the normal growth of C .radicans. The high P N and WUE were recorded when PAR ranged from 800 to 1600 µmol/m 2 /s and the light saturation points ranged from 800 to 1400 µmol/m 2 /s. The peak value of LUE was found when PAR ranged from 100 to 300 µmol/m 2 /s, indicating that the C. radicans had high adaptability to light conditions.

Growth and photosynthetic responses of Fraxinus mandshurica seedlings to various light environments

“…LCP and LSP were effective indicators of light requirements of plants, and sciophytes generally exhibited lower values than heliophytes (Larcher 2003). LCP of F. mandshurica seedlings under different light levels during the growing season varied from 12.68 to 64.47 μmol·m -2 ·s -1 , which was between sciophyte (LCP < 20 µmol·m -2 ·s -1 ) and heliophyte (LCP > 50 µmol·m -2 ·s -1 ), (Xia et al 2008). LSP of F. mandshurica seedlings increased with the increasing of light level, indicating the good adaptability and plasticity in changes of light regimes.…”

Response of Morphological Characters and Photosynthetic Characteristics of Haloxylon ammodendron to Water and Salt Stress

“…Our results showed that with the decrease of water content, the maximum net photosynthetic rate of Haloxylon ammodendron in gradients II, III, and IV showed a slight upward trend, further confirming that Haloxylon ammodendron in this gradient was more affected by water and salt stress. AQY is an index used to characterize the light energy conversion efficiency of plant leaves and the ability to use weak light for photosynthesis [37]. The higher the value, the stronger the ability.…”

Эколого-Биологическая Оценка Вьющихся Кустарников Для Вертикального Озеленения Территорий

“…Studies on the water regime and colloidal osmotic properties of protoplasm carried out in laboratory conditions. The main attention was paid to the characteristics of the growth and development of plants, their resistance to the environment, and economical use (Jiang-bao, 2011;Novikova, 2019;Baumgartner, 2020).…”