Heat stress and the photosynthetic electron transport chain of the lichen Parmelina tiliacea (Hoffm.) Ach. in the dry and the wet state: differences and similarities with the heat stress response of higher plants

Thalli of the foliose lichen species Parmelina tiliacea were studied to determine responses of the photosynthetic apparatus to high temperatures in the dry and wet state. The speed with which dry thalli were activated by water following a 24h exposure at different temperatures decreased as the temperature was increased. But even following a 24h exposure to 50°C the fluorescence induction kinetics OJIP reflecting the reduction kinetics of the photosynthetic electron transport chain had completely recovered within 128min. Exposure of dry thalli to 50°C for 24h did not induce a K-peak in the fluorescence rise suggesting that the oxygen evolving complex had remained intact. This contrasted strongly with wet thalli were submergence for 40s in water of 45°C inactivated most of the photosystem II reaction centres. In wet thalli, following the destruction of the Mn-cluster, the donation rate to photosystem II by alternative donors (e.g. ascorbate) was lower than in higher plants. This is associated with the near absence of a secondary rise peak (~1s) normally observed in higher plants. Analysing the 820nm and prompt fluorescence transients suggested that the M-peak (occurs around 2-5s) in heat-treated wet lichen thalli is related to cyclic electron transport around photosystem I. Normally, heat stress in lichen thalli leads to desiccation and as consequence lichens may lack the heat-stress-tolerance-increasing mechanisms observed in higher plants. Wet lichen thalli may, therefore, represent an attractive reference system for the evaluation of processes related with heat stress in higher plant

Phenotyping of dark and light adapted barley plants by the fast chlorophyll a fluorescence rise OJIP

Chlorophyll a fluorescence of dark adapted leaves of barley plants (Hordeum vulgare L.) upon exposure to actinic light was measured. We compared the photosynthetic behaviour of ten cultivars of barley plants in the dark and light adapted states. A significant relationship between the light adaptation (S1 to S2 transition) of the photosynthetic Performance Index (lPI/dPI) and the normalised Area (lSm/dSm) evaluated by the JIP-test was observed. The two parameters might provide a basis to rank the plants according to their tolerance to light stress conditions, i.e. the studied cultivars can be split into three groups with a different response to high light stress: tolerant, intermediate and sensitive

Etude De L’impact De La Consanguinité Sur La Santé Des Descendants Dans La Population De Tiflet (Maroc)

Several studies confirm the implication of the consanguinity in health problems and some countries still preserve this marital behavior. In this study, our objective is the analysis of consanguinity’s impact on descendants’ health in the Tiflet city and its regions (Northwest of Morocco). Data was collected between June and November 2012 and it was conducted on 1000 families. The calculation of the rate of the mortality concerned 3345 alive born descendants, while the biological effects of the consanguinity study was made on 3241 descendants. The results of this study show a significant association between the consanguinity and its incidence on health, such as the morbidity, the mortality and the abortion in the descendants

Études Des Caractéristiques Et Des Déterminants Des Mariages Consanguins Dans La Ville De Tiflet (Maroc)

The practice of consanguineous marriage is still very widespread in Morocco and in the Arab-Muslim world, where the customs as well as the cultural, economic and social motivations have most often an influence on the marital choice within the family. The purpose of this study is to define the determinants of this practice in the city of Tiflet and regions (Morocco). A survey was conducted on 1000 pairs randomly sampled between June and November of 2012. The results reveal a high level of consanguinity (38.9 %) and a significant association between this marital practice and the geographical and sociocultural factors such as: the place of residence before marriage, the education level, the profession and the age in the marriage

Polyphosphate application influences morpho-physiological root traits involved in P acquisition and durum wheat growth performance

peer reviewedAbstract Background Among phosphate (P) fertilizers, polyphosphates (PolyPs) have shown promising results in terms of crop yield and plant P nutrition. However, compared to conventional P inputs, very little is known on the impact of PolyPs fertilizers on below- and above-ground plant functional traits involved in P acquisition. This study aims to evaluate agro-physiological responses of durum wheat variety ´Karim´ under different PolyPs applications. Three PolyPs fertilizers (PolyA, PolyB, and PolyC) versus one orthophosphate (OrthoP) were applied at three doses; 30 (D30), 60 (D60), and 90 (D90) kg P/ha under controlled conditions. The PolyPs (especially PolyB and PolyC) application at D60 significantly increased morphophysiological root traits (e.g., RL: 42 and 130%; RSA:40 and 60%), shoot inorganic P (Pi) content (159 and 88%), and root P acquisition efficiency (471 and 296%) under PolyB and PolyC, respectively compared to unfertilized plants. Above-ground physiological parameters, mainly nutrient acquisition, chlorophyll content and chlorophyll fluorescence parameters were also improved under PolyB and PolyA application at D60. A significant and positive correlation between shoot Pi content and rhizosphere soil acid phosphatase activity was observed, which reveal the key role of these enzymes in PolyPs (A and B) use efficiency. Furthermore, increased P uptake/RL ratio along with shoot Pi indicates more efficient P allocation to shoots with less investment in root biomass production under PolyPs (especially A and B). Conclusions Under our experimental conditions, these findings report positive impacts of PolyPs on wheat growth performance, particularly on photosynthesis and nutrient acquisition at D60, along with modulation of root morpho-physiological traits likely responsible of P acquisition efficiency

Les réponses morphologiques et anatomiques des racines de blé à des concentrations croissantes du phosphore sous des conditions de salinité

peer reviewedUnderstanding the role of nutrients in the alleviation of salt stress effects and the unrevealed significance of root system architecture for plant adaptation is one of the major research areas in the current context of agriculture. Root anatomy is also a valuable parameter to be considered in understanding how the root system counters soil salinity's effect on plant growth. Although Root Phosphorus Acquisition Efficiency (RPAE) under salt stress differs depending on plant species and the severity of salinity in the rhizosphere, optimising phosphorus (P) nutrition seems to bring positive results. This study was planned to investigate the combined effect of salinity and P-availability on root morphology and anatomy as well as nutrient uptake of wheat plants. A pot experiment was performed in open-field conditions using a Moroccan variety of durum wheat. Special emphasis was placed on how orthophosphate and polyphosphate fertilizer forms and phosphorus doses alter the morphology and anatomy of the roots under salt stress. Two soluble fertilizers were used: an orthophosphate (Ortho-A) and a polyphosphate (Poly-B) were applied at four P levels (0, 30, 45 and 60 ppm of P). Our findings showed that salt stress induced, at both anatomical and morphological levels, a series of modifications in the roots of wheat plants. Compared to salt-stressed and unfertilized plants, soluble P-fertilizers significantly increased soil available P, root P- content, RPAE, root length (RL), root surface area (RSA), root volume (RV), root mass density (RMD), root tissue water content (TWC), number of root tips, vascular cylinder diameter and SD/CT ratio. Furthermore, Poly-B showed a positive response in both morphological and anatomical parameters at lower doses while Ortho-A revealed significant results within the increase in P-concentration. The increased root parameters observed under P-treatments could determine the root performance and efficiency to acquire water and P and their transport to the aboveground organs of wheat plants under salinity

Optimization of macronutrients for improved grain yield of quinoa (Chenopodium quinoa Wild.) crop under semi-arid conditions of Morocco

In the context of climate change, quinoa represents a potential alternative crop for increasing crops diversity, agricultural productivity, and farmer’s income in semi-arid regions. However, appropriate crop management practices under limited water supply are still poorly documented. Quinoa, like other cultivated crops, needs optimum quantities of nutrients, especially nitrogen (N), phosphorus (P), and potassium (K), for better growth and high grain yield. To determine the adequate levels of nutrient requirements and their effect on quinoa growth and productivity, a field experiment was conducted during two growing seasons (2020–2021 and 2021–2022). The experiment was conducted in Ben Guerir region, north-central Morocco, and consisted of a randomized complete block design (RCBD) with three replications. The treatments studied consist of a combination of four N rates (0, 40, 80, and 120 kg ha−1), three P rates (0, 30, and 60 kg P2O5 ha−1), and three K rates (0, 60, and 120 kg K2O ha−1). The physiological, nutritional, and production parameters of quinoa were collected and analyzed. The results showed that the highest total biomass (3.9 t ha−1) and grain yield (0.8 t ha−1) under semi-arid conditions were obtained with 40 kg N ha−1, 60 kg P2O5 ha−1, and 120 kg K2O ha−1. The application of 40–60–120 kg ha−1 of N–P2O5–K2O increased plant height by 44%, chlorophyll content index by 96%, total biomass by 134%, grain yield by 112%, and seed weight by 118%. Among the three macronutrients, N was the most limiting factor, followed by K and P. Nutrients uptake data showed that quinoa needs 60 kg N, 26 kg P2O5, and 205 kg K2O to produce 1 t of grain yield. Our field results provide future recommendations for improving the agronomic and environmental sustainability of quinoa cultivation in dryland areas in Morocco