Gabriella Frosi

Ecophysiological performance of Calotropis procera: an exotic and evergreen species in Caatinga, Brazilian semi-arid

To better understand the proliferation of Calotropis procera in a semi-arid region of northeastern Brazil (Caatinga), we designed two experiments to determine which ecophysiological characteristics contribute to the species adaptive success. The first experiment was conducted with young plants under greenhouse conditions and three water regimes. The second experiment was conducted with adult plants under field conditions subject to regional seasonality. Young plants exhibited a high tolerance to water deficits, mainly because of their strong stomatal control, which was observed before any biochemical alterations in leaf metabolism. Only under full suspension of irrigation did the plants show a reduction in relative water content. Under field conditions, adult plants showed a high resilience to the semi-arid environment with respect to gas exchange and other measured biochemical parameters, including photosynthetic pigment, soluble sugars, amino acids and protein content, even under the low soil water availability of the dry season. This season featured high photosynthetically active radiation, low relative humidity and high temperatures, and thus exposed plants to extreme differences between leaf and air temperatures. Calotropis procera remains green throughout the year, indicating that it has developed several means of tolerating the semi-arid climate. Furthermore, this species maintains a high photosynthetic rate despite reduced stomatal conductance, which increases its water use efficiency, a fundamental characteristic for survival in this ecosystem.

Symbiosis with AMF and leaf Pi supply increases water deficit tolerance of woody species from seasonal dry tropical forest

In seasonal dry tropical forests, plants are subjected to severe water deficit, and the arbuscular mycorrhizal fungi (AMF) or inorganic phosphorus supply (Pi) can mitigate the effects of water deficit. This study aimed to assess the physiological performance of Poincianella pyramidalis subjected to water deficit in combination with arbuscular mycorrhizal fungi (AMF) and leaf inorganic phosphorus (Pi) supply. The experiment was conducted in a factorial arrangement of 2 water levels (+H2O and -H2O), 2 AMF levels (+AMF and -AMF) and 2Pi levels (+Pi and -Pi). Leaf primary metabolism, dry shoot biomass and leaf mineral nutrients were evaluated. Inoculated AMF plants under well-watered and drought conditions had higher photosynthesis and higher shoot biomass. Under drought, AMF, Pi or AMF+Pi plants showed metabolic improvements in photosynthesis, leaf biochemistry and higher biomass compared to the plants under water deficit without AMF or Pi. After rehydration, those plants submitted to drought with AMF, Pi or AMF+Pi showed a faster recovery of photosynthesis compared to treatment under water deficit without AMF or Pi. However, plants under the drought condition with AMF showed a higher net photosynthesis rate. These findings suggest that AMF, Pi or AMF+Pi increase the drought tolerance in P. pyramidalis, and AMF associations under well-watered conditions increase shoot biomass and, under drought, promoted faster recovery of photosynthesis.

Ecophysiological leaf traits of native and exotic palm tree species under semi-arid conditions

AbstrA ct: The main goal of this study was to evaluate the performance of two palm species under semi-arid conditions during the rainy and dry periods: the semi-arid native Syagrus coronata and a native to tropical America, Acrocomia aculeata. The leaf water potential, gas exchange, leaf soluble sugars, starch, free amino acids, total soluble protein content and morphological traits were measured. The highest leaf water potential and CO 2 assimilation values in both species were achieved during the rainy period. In response to the low soil moisture content during the dry period, gas exchange decreased 72 and 92% in S. coronata and A. aculeata, respectively,

Arbuscular mycorrhizal fungi and foliar phosphorus inorganic supply alleviate salt stress effects in physiological attributes, but only arbuscular mycorrhizal fungi increase biomass in woody species of a semiarid environment

Salinity may limit plant growth especially in arid and semiarid regions. Arbuscular mycorrhizal fungi (AMF) and the supply of inorganic phosphorus (Pi) could alleviate the negative effects of such stress by improvement in stomatal conductance, photosynthesis and biomass. The aim of this study is to evaluate the ecophysiological performance of Cenostigma pyramidale (Tul.) E. Gagnon & G. P. Lewis (Fabaceae) in a greenhouse under salinity conditions in combination with the supply of AMF and leaf Pi. The experiment was conducted in a factorial design considering two levels of salinity (+NaCl and -NaCl), two levels of AMF (+AMF and -AMF) and two levels of leaf Pi supply (+Pi and -Pi). The variables gas exchange, leaf primary metabolism, dry biomass and nutrients were measured. Plants with AMF under non-saline conditions presented a high photosynthesis and biomass. In saline conditions, AMF promoted lower decrease in photosynthesis, high shoot dry matter and low content of leaf and root Na+ and Cl-. Plants treated with leaf Pi increased biomass and photosynthetic pigments under both conditions and accumulated more Cl- in shoots under salinity conditions. When combined, AMF * Pi increased photosynthesis only in non-saline conditions. Plants under salinity conditions without AMF and Pi had higher decreases in gas exchange and high content of Cl- in roots. Therefore, C. pyramidale plants improved their metabolism under both growth conditions in the presence of AMF, Pi or a combination of both. However, the greatest increases in growth and tolerance to salinity occurred in the isolated presence of AMF.

Changes in phenotypic variability of two tropical woody species due to short and long-term exposure to different irradiances

Bragantia, Campinas, v. 77, n. 3, p.429-439, 2018 ABSTRACT: Studies addressing the physiological and anatomical responses of plants under different light intensities normally are performed in short term. Thus, the present study includes a long term analysis. This study aims to verify whether the phenotypic variability off attributes in two woody tropical specieis, Paquira aquatica and Sterculia foetida, are compatible both under short term exposure to different light availability levels (full-light and half-light local irradiance) and long-term exposure in the same conditions. The study was developed in two phases: phase I (short term) and phase II (long term). The variables measured were referent to CO2 assimilation responses to light intensity, chlorophyll a fluorescence, chlorophyll content, morpho-anatomical attributes and phenotypic variability. In phase I, P. aquatica had differences between treatments in Amax (maximum net photosynthesis) and LCP (light compensation point), without differences in these attributes in phase II. S. foetida BASIC AREA Article

Estratégias para tolerar o estresse salino em duas espécies lenhosas tropicais

This study aimed to evaluate the leaf primary metabolism in two woody species, Sterculia foetida and Bombacopsis glabra. Both species have seeds rich in oil and they are largely found in regions with irregularities in water availability. Seedlings were grown in a greenhouse from seeds. At 140 days after emergence, 50% of the plants were subjected to salt stress for 23 days, daily receiving 100 mM of NaCl solution. In both species, leaf stomata conductance and water potential decreased quickly under salt stress. The two species showed different strategies in photosynthetic pigment concentration and components of nitrogen metabolism. S. foetida kept the pigment concentration unchanged after 23 days of stress, while B. glabra increased concentration of chlorophyll a and carotenoids. S. foetida showed a high leaf concentration of K+ in stressed plants and a Na+/K+ ratio without differences when compared to control. Thus, S. foetida presented a better ionic balance, while B. glabra invested in photoprotection. Therefore, both species present potential to be planted in Brazilian Northeast, where water deficit and salt stress are challenging for annual crops. Estratégias para tolerar o estresse salino em duas espécies lenhosas tropicais Resumo O estudo teve como principal objetivo avaliar o metabolismo primário foliar de duas espécies lenhosas, Sterculia foetida e Bombacopsis glabra, de sementes ricas em óleo e amplamente encontradas em regiões com disponibilidade hídrica irregular. As duas espécies foram cultivadas em casa de vegetação a partir de sementes. Aos 140 dias após a emergência, 50% das plantas foram submetidas ao estresse salino durante 23 dias, recebendo diariamente uma solução de 100 mM de NaCl. As duas espécies rapidamente reduziram a sua condutância estomática e o potencial hídrico foliar, em relação às plantas controle. S. foetida e B. glabra apresentaram estratégias diferentes quanto ao conteúdo de pigmentos fotossintéticos e componentes do metabolismo do nitrogênio. S. foetida manteve seus pigmentos intactos após 23 dias de estresse, enquanto B. glabra aumentou o conteúdo de clorofila a e carotenoides. S. foetida apresentou alto teor foliar de K+ e uma relação Na+/K+ sem diferença nas plantas estressadas comparadas com as do controle. Portanto, S. foetida apresentou um melhor em balanço iônico, enquanto B. glabra investiu em fotoproteção. Assim, as duas espécies são alternativa potencial para serem cultivadas no Nordeste brasileiro, onde condições de estresse hídrico e salinidade são restritivas para culturas anuais. ISSN: 1983-2605 (online)