The effect of irradiance and water restriction on photosynthesis in young jatobá-do-cerrado (Hymenaea stigonocarpa) plants

Abstract

High irradiance promotes decreases in the quantum yield in plants, which reduce the photosynthetic rate. The excess of light in combination with water deficit can intensify the response of plants to stress, especially in species susceptible to those factors. The aim of the present study was to characterize the photosynthetic activity of young jatobá-do-cerrado (Hymenaea stigonocarpa Mart. ex Hayne) trees under different irradiance conditions, both alone and/or in combination with water deficit. Four irradiances [45, 230, 510, and 1,700 μmol(photon) m -2 s -1 ] and two levels of water in soil (90% and 50% of field capacity) were used. Gas exchange, water potential, and chlorophyll a fluorescence were measured. The highest rates of photosynthesis were observed under irradiances of 230 and 510 μmol(photon) m -2 s -1 . Irradiance of 1,700 μmol(photon) m -2 s -1 led to the photoinhibition of photosynthesis, as indicated by a reduced maximum quantum yield of PSII, effective quantum yield ratio, and electron transport rate, as well as higher nonphotochemical quenching. The most stressful to young H. stigonocarpa plants was high irradiance, while water deficit did not intensify the response to light stress.

In Situ Hyperspectral Remote Sensing for Monitoring of Alpine Trampled and Recultivated Species

“…Therefore, the measurements confirmed the dependence, namely that plants exposed to abiotic and biotic stress show lower than 0.830 or 0.832 ± 0.004 F v /F m values [86,87], with a decrease of F v /F m and mechanic damage to plant tissues causing disturbed transport within the plant and a drop in biomass and overall robustness [88]. However, high photosynthetically active light intensity can also lead to stress in plants, with a drop in the rate of F v /F m [89]. Therefore, in shady sites, trampling can lead to less vegetation damage and a smaller drop in biodiversity [90].…”

<b>Morphoanatomy and physiology of Pouteria gardneriana Radlk plantlets grown in vitro at varied photosynthetic photon flux densities

“…Although a lower Fv/Fm ratio was observed in the plantlets cultured at 150 μmol m -2 s -1 they did not demonstrate photoinhibition and the biomass accumulation was higher. Photoinhibition was observed in apple plants cultured in vitro (Zanandrea, Bacarin, Falqueto, Braga, & Peters, 2007) and in young 'jatobá-docerrado' (Hymenaea stigonocarpa) plants grown in a greenhouse (Costa et al, 2015), when they were exposed to PPFDs higher than the ideal range for photosynthesis.…”

Biochemical and physiological impacts of zinc sulphate, potassium phosphite and hydrogen sulphide in mitigating stress conditions in soybean

“…Two independent experiments were performed with the application of the treatments at the development stages vegetative (V4, third trifoliate fully expanded) and reproductive (R1, bloom beginning), respectively. At each stage, the water regime was implemented using the gravimetric method (Costa et al ) in order to maintain the plants well‐watered (WW) and under water deficit (WD), using 100 or 50% of the maximum water holding capacity (MWHC), respectively. The compounds used to make the nutrient solution were as follows: potassium phosphite (PP) in 0.75 c. p. ha −1 (GRAP PHILL, 30% P 2 O 5 , 20% K 2 O), hydrogen sulphide (HS) in 0.66 dose c. p. ha −1 (sodium hydrosulphide [NaHS], donor of HS, Sigma‐Aldrich), and zinc sulphate (ZS) in 1.98 c. p. ha −1 (ZnSO 4 ·7H 2 O, Sigma‐Aldrich).…”