Acclimation to sun and shade of three accessions of the Chilean native berry-crop murta

Abstract

Murta (Ugni molinae Turcz.) is an evergreen shrub of the native forest understorey of southern Chile that produces berries which are consumed in the local markets. Because of the natural adaptation of murta to growing under the shade of trees, we propose that an adequate way of domesticating this species would be its cultivation in agroforestry systems. In order to assess the suitability of three murta accessions from different regions in southern Chile for their cultivation in such systems, we established a trial in which these accessions were submitted to six light transmittance levels (20%-100% of full solar irradiance) from planting in spring to the following autumn. Optimum growth, as assessed through dry mass accumulation and emission of branches and metamers, was achieved at moderate light transmittance levels (50%-65%). These growth traits showed stable positive responses to the relative amount of light intercepted by the plants (as estimated from plant structural traits) up to these optimum light transmittance levels and diverged to lower values thereafter. These stable relationships suggest that the differences in plant growth at low and moderate light transmittance levels can be attributed to restrictions of photosynthesis by light availability. The reduction in growth for higher light transmittance levels may be partly attributed to photoinhibition as suggested by reduced chlorophyll content and relatively low increments in carotenoid content in leaves at high light transmittance levels.

Changes in Photosynthetic Pigments Content in Non-Transformed and AtCKX Transgenic Centaury (Centaurium erythraea Rafn) Shoots Grown under Salt Stress In Vitro

“…During the process of Chl degradation, Chl b is converted to Chl a, and this might explain the increment of the Chl a/Chl b ratio [78]. Traditionally, the sun-shaded tolerance in plants has been defined based on the Chl a/Chl b ratio [79,80]. The Chl a/Chl b ratio has variable values, and when the ratio is ~3, it is clear that plants are adapting to the light conditions.…”

Effectiveness of photochemical reflectance index to trace vertical and seasonal chlorophyll a/b ratio in Haloxylon ammodendron

“…Since short-term increase in light enhances light harvesting in plants, Chl a/b ratio has been applied as a measure for plants' tolerance to irradiance in many species (Kitajima and Hogan 2003;Johnson et al 1993). As plants growing at high light increases the amount of light utilization components to maintain the balance by having higher Chl a/b ratios (Franck et al 2007;Terashima and Evans 1988), H. ammodendron was expected to exhibit lower Chl a/b ratio at the end of the growing season when meteorological variables were minimal. However, the opposite response was observed where the detailed mechanism that explains the response of PRI during senescence when Chl a/b ratio was the highest was assumed to be related to elevated stress arising from drought.…”

“…The response of PRI to changes in Chl a/b ratio emanating from degradation of chlorophyll at the end of the growing season emphasized the importance of considering age-related changes in plant leaves when assessing their physiological response to stress. However, this study focused on stratum (canopy heights) and temporal (seasonal) relationship between Chl a/b ratio and PRI, and hence an increase in Chl a/b ratio during the 3-year growing seasons may have aided in reducing the excess energy buildup in PSII (Franck et al 2007), especially within the bottom canopy branches. This was evidenced from unaffected annual pattern in Chl a/b ratio, which implied that the PRI signal may be an effect of interrelated factors within the ecosystem that affected the reaction centers of branches within the canopy throughout the growing season as they respond to stress.…”

The combined effects of soil moisture and irradiance on growth, biomass allocation, morphology and photosynthesis in Amomum villosum

“…The influential trade-off hypothesis (Smith and Huston 1989) predicts that drought has stronger impacts on individuals of a species grown in deep shade than on those under higher irradiance. Compared with plant grown at higher irradiance, shaded-plant generally has a higher specific leaf area (SLA) and invests more biomass to leaves but less to roots for efficient light capture (Poorter 1999;Feng et al 2007;Franck et al 2007), which might decrease its drought tolerant ability. According to above-ground facilitation hypothesis (Holmgren 2000) shade decreases leaf and air temperature, leaf-to-air vapour pressure deficit (Ishida et al 1999), oxidative stress, and therefore can reduce the impacts of drought on growth and photosynthesis (Valladare and Pearcy 1997).…”