Characteristics of leaf photosynthesis and simulated individual carbon budget in Primula nutans under contrasting light and temperature conditions

Abstract

Primula nutans Georgi is widely distributed in hummock-and-hollow wetlands on the Qinghai-Tibetan Plateau. To assess the ecophysiology of this species in responding to microenvironments, we examined the photosynthetic characteristics and individual carbon gain of plants growing in different microsites from a hummock-and-hollow wetland on the Qinghai-Tibetan Plateau and under laboratory conditions. Plants from wetland hummock microsites showed significantly higher light-saturated photosynthetic CO(2) uptake (A (max)) than those from microsites in hollows at a controlled temperature of 15 degrees C in leaf chamber. Leaf dark respiration rate (R) was only significantly higher in plants from hummocks than hollows at the measuring temperature of 35 degrees C. Optimum temperature for A (max) was 15 degrees C for all plants in the field despite different microsites. In plants growing under laboratory conditions differing in light and temperature, both A (max) and R were significantly higher under higher growth light (photosynthetic photon flux density, PPFD: 800 or 400 micromol m(-2) s(-1)) than low light of 90 micromol m(-2) s(-1). No statistically significant differences in A (max) and R existed in plants differing in growing temperatures. Estimates derived from the photosynthetic parameters of field plants, and microsite environmental measures including PPFD, air temperature and soil temperature showed that the optimum mean daily temperature for net daily carbon gain was around 10 degrees C and the net daily carbon gain was largely limited under lower daily total PPFD. These results suggest that the differences in A (max) and R in P. nutans are strongly affected by growing light regimes but not by temperature regimes.

Effects of low irradiation on photosynthesis and antioxidant enzyme activities in cucumber during ripening stage

“…The primary reason may be that the LI stress caused disorder of chloroplast ultrastructure and aggravated its degradation, leading to reduction of chlorophyll content. P max , which was consistent with chlorophyll, decreased under LI, in accordance with Shen et al (2008). The reason may be that low light availability results in significant reduction of carbon gain in the plants.…”

“…Ren et al (2002) have reported that SOD activity of tomato leaves decreased under LI stress. LI also reduced F v /F m , ETR, and --- Ernstsen et al 1999, Andersen and Pedersen 2002, Miko et al 2004, Shen et al 2008. The study has reported that LI stress significantly reduced the chlorophyll content in leaves of Arabidopsis thaliana (Tanaka and Tanaka 2005), henbit genus (Haliapas et al 2008), and rice (Yamazaki 2010).…”

Anti-Ulcer activity of methanol extract of Plantago rugelii Decne. (Plantaginaceae)

“…They also aid in the biological actions for which they are identified in folk medicine. The geographical distribution of plants, affect both the morphology and expression of phytochemicals [24,25] , this may be the case with P. rugelii which lacked tannin, anthraquinone and phenolic compounds. The results of the phytochemical composition of the whole plant powder consisting of the roots, stem and leaves showed that the plant has an appreciable number of phytochemicals.…”

Phytochemical, Antioxidant, Proximate, and Selected Mineral Status of Egyptian Citrus paradisi Fruit obtained from Wamakko Local Government Area of Sokoto State, North-western Nigeria

“…These differences may be attributed to differences in species as well as the geographical location which is known to affect both the morphology and expression of phytochemicals. [32,33] DPPH is usually used as a reagent to evaluate free radical scavenging activity of antioxidants because it is as table free radical which accepts an electron or hydrogen radical to become a stable diamagnetic molecule. [8] The fruit concentrates exhibit a reasonable antioxidant potential but not statistically significant (P < 0.05) to that of the ascorbic acid standard [ Table 2].…”