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Photosynthetic responses of tomato leaves to salt and cadmium stresses: growth and chlorophyll a fluorescence kinetic analyses

100%

Gharbi F. , Zribi L. , Daly A. B. , Rejeb S. , Hanchi B.

Polish Journal of Environmental Studies

2018

tom 27

nr 6

This study investigated the effects of salinity (NaCl) and cadmium (Cd) on leaf growth and photosynthetic parameters of tomato plants (Solanum lycopersicum cv. Rio Grande). Cd and NaCl treatments considerably reduced leaf dry matter and leaf area of tomato plants. Stomatal conductance decreased significantly with increased NaCl and Cd in the growth medium, with the decrease occurring at an early stage under Cd treatments. For the fluorescence parameters, there was no significant difference in the maximum quantum efficiency of PSII (Fv/Fm) for either type of stress. However, the quantum yield of PSII photochemistry (ΦPSII), photochemical quenching (qp), and the intrinsic efficiency of PSII (Фexc) decreased significantly under both NaCl and Cd treatments. Decreases in ΦPSII, qp, and Фexc were coupled with a significant increase in non-photochemical quenching (NPQ), and the highest NPQ was obtained in NaCl-treated plants. The correlation between electron transport rate (ETR) and stomatal conductance showed that stomatal closure is associated with a down-regulation of ETR, which is compensated by an increase in non-photochemical quenching.

Isotopic evaluations of dynamic and plant uptake of N in soil amended with 15N-labelled sewage sludge

86%

Kchaou R. , Khelil M. N. , Gharbi F. , Rejeb S. , Henchi B. , Hernandez T. , Destain J. P.

Polish Journal of Environmental Studies

2010

tom 19

nr 2

363-370

Field experiments were conducted to evaluate the use of a novel ¹⁵N isotope technique for comparing the dynamics of N derived from sewage sludge applied to sorghum to the dynamics of N derived from the commercial fertilizer, urea. The treatments included a control, sludge applied at three rates (3, 6 and 9 t/ha, or 113, 226 and 338 kg N/ha) and N-urea applied at three rates (150, 250 and 350 kg N/ha). Recovery of ¹⁵N-labelled sludge was similar for the different nitrogen rates applied, with a mean value of 27%. However, the recovery of ¹⁵N-urea decreased as the rate of N application increased (from 38% to 27%). Approximately 22% and 19% of the ¹⁵N from sludge and urea, respectively, remained in the 0-60 cm layer of soil, most of which was present in the 0-20 cm layer. Furthermore, losses of ¹⁵N-labelled fertilizer were not affected by the N fertilization source, and the greatest losses, which were measured in response to the highest N application rate, were 59%.

Short-term response of wild grapevines (Vitis vinifera L. ssp. sylvestris) to NaCl salinity exposure: changes of some physiological and molecular characteristics

72%

Askri H. , Daldoul S. , Ammar A. B. , Rejeb S. , Jardak R. , Rejeb M. N. , Mliki A. , Ghorbel A.

nr 3

The physiological and molecular response to salt stress was studied in two wild grapevine (Vitis vinifera L. ssp. sylvestris or Vitis sylvestris) accessions ‘‘Khédhayria’’ and ‘‘Houamdia’’, previously identified as salt-tolerant and salt-sensitive pair wise. Plants from both accessions were subjected to a progressive salt stress by the use of a nutritional solution containing up to 150 mM NaCl for 2 weeks. Salt stress adversely affected growth and water potential since the first day of exposure to 150 mM NaCl. However, chlorophyll fluorescence parameters were unchanged until 14 days of salt exposure. At that time point the predawn water potential (ΨPD), the non-photochemical quenching of fluorescence (NPQ) and the coefficient of photochemical quenching (qp) were significantly less altered in the tolerant accession. At the molecular level semi-quantitative RT-PCR assays revealed a differential expression of (Vs α-gal/SIP and Vs DHN) genes within these contrasting accessions after exposure to 24 h and 14 days of salt. Comparably, the Vs RD22 gene had increased slightly after only 14 days of treatment in both accessions. These results were the first pieces of information reported on the early and late regulation of salt response genes in wild grapevines. Furthermore, genotype-dependent parameters such as NPQ, qp, mRNA levels of Vs α-gal/SIP and Vs DHN could be used to screen salt-tolerant wild grapevine genotypes.