Cadmium (Cd) is considered one of the heavy metals disturbing plant biophysiological functions. The potential role of phosphorus (P) nutrition in the attenuation of Cd effects on photosynthetic ...efficiency, plant growth, and cadmium uptake has been investigated in hydroponically grown tomato. Two P nutrition regimes (P15: 15 mg l
-1
; P30: 30 mg l
-1
) were assessed in the presence or absence of Cd (Cd0: 0 μM; Cd25: 25 μM of CdCl
2
). The results showed a positive effect of P30 concentration on leaf chlorophyll content and chlorophyll a fluorescence compared to P15 treatment under Cd stress (Cd25). The disturbance of electron transfer caused by Cd at K and I-steps of OJIP transient was attenuated with sufficient P supply. P30 enhanced the performance index of photosystem II and the efficiency of electron transfer to electron acceptor at PSI acceptor side. Besides, increased P concentration improved root growth parameters and biomass accumulation in the presence of Cd. It was found that root tissues accumulated more Cd than shoots and Cd translocation was reduced with increasing P concentration. Our results reveal that Cd-P interaction induced a cascade of physiological and chemical changes in plants. An optimal P nutrition can attenuate Cd stress on plant by the promotion of nitrogen and potassium uptake, which in return improved photosynthesis efficiency, enhanced biomass accumulation and distribution, and minimized Cd accumulation and translocation in plant tissues.
Simultaneous in vivo measurements of prompt fluorescence (PF), delayed fluorescence (DF) and modulated reflection (MR) at 820-nm were used to assess effect of short desiccation period (4.5 h) on ...Parmelina tiliacea lichen. The two performance indexes (PIABS and PItotal) as a measure of an overall photosynthetic thalli performance showed a negative effect of desiccation treatment on photosynthetic activity. The maximal intensity of PF and DF recorded during desiccation treatment decreased and at 4.5 h desiccation time Parmelina tiliacea thalli loss their variable fluorescence and DF amplitude. This loss of variable fluorescence was due to an increase in inactive reaction centers and a limitation of electron donation on the donor side of photosystem II (PSII) that caused a down-regulation of electron transport chain at the PSII level. However, the efficiency with which an electron can move from the reduced intersystem electron acceptors to the PSI end electron acceptors was less affect by desiccation treatment. In respect to MR change, re-reduction kinetics of the primary electron donors of photosystems I (P700) and plastocyanin (PC) in desiccated thalli seem to be faster, their amplitudes gradually decrease and a disconnection between the two photosystem (PSII and PSI) were observed. These responses allow to Parmelina tiliacea lichen a photoprotection mechanism from the excess light excitation.
Main conclusion
Some salt stress response mechanisms can translate into sorghum forage yield and thus act as targets for genetic improvement.
Sorghum is a drought-tolerant cereal that is widely grown ...in the vast Africa’s arid and semi-arid areas. Apart from drought, salinity is a major abiotic factor that, in addition to natural causes, has been exacerbated by increased poor anthropological activities. The importance of sorghum as a forage crop in saline areas has yet to be fully realized. Despite intraspecific variation in salt tolerance, sorghum is generally moderately salt-tolerant, and its productivity in saline soils can be remarkably limited. This is due to the difficulty of replicating optimal field saline conditions due to the great heterogeneity of salt distribution in the soil. As a promising fodder crop for saline areas, classic phenotype-based selection methods can be integrated with modern
-omics
in breeding programs to simultaneously address salt tolerance and production. To enable future manipulation, selection, and genetic improvement of sorghum with high yield and salt tolerance, here, we explore the potential positive correlations between the reliable indices of sorghum performance under salt stress at the phenotypic and genotypic level. We then explore the potential role of modern selection and genetic improvement programs in incorporating these linked salt tolerance and yield traits and propose a mechanism for future studies.
Salt stress is considered one of the major constraints limiting plant growth. Here, tomato plants were grown in hydroponic culture with two salt sodium chloride concentrations (S1 = 2.8 dS m
−1
and ...S2 = 4.8 dS m
−1
). Under salt treatment, a significant decrease in chlorophyll content index and shoot and root dry weight were observed. We found that copper (Cu) was accumulated significantly in the shoot and sodium (Na) was significantly accumulated in the root. Furthermore, a significant nutrient imbalance indicated by a decrease in phosphorus (P), and potassium (K) uptake was measured. These decreases were accompanied by an increase in Na and Cu contents. A decrease in chlorophyll fluorescence yield was also observed indicating an inhibition at photosystem I acceptor sites. It seems that the downregulation of the electron transport between photosystem II and photosystem II under salt stress could be due to an imbalance in nutrient uptake.
In this work, we assessed the drying and composting effectiveness of helminth eggs removal from sewage sludge of a lagoon wastewater treatment plant located in Chichaoua city. The composting was run ...after mixing sludge with green waste in different proportions: M1 (½ sludge + ½ green waste), M2 (
2
3
sludge +
1
3
green waste), and M3 (
1
3
sludge +
2
3
green waste) for 105 days. The analysis of the dewatered sewage sludge showed a load of 8–24 helminth eggs/g of fresh matter identified as
Ascaris
spp. eggs (5–19 eggs/g) followed by
Toxocara
spp. (0.2 to 2.4 eggs/g);
Hookworm
spp. and
Capillaria
spp. (0.4–1 egg/g);
Trichuris
spp.,
Taenia
spp., and
Shistosoma
spp. (< 1 egg/g) in the untreated sludge. After 105 days of treatment by composting, we noted a total reduction of helminth eggs in the order of 97.5, 97.83, and 98.37% for mixtures M1, M2, and M3, respectively. The
Ascaris
spp. eggs were reduced by 98% for M1 and M3 treatments and by 97% for M
2
Treatment.
Toxocara
spp.,
Hookworm
spp.,
Trichuris
spp.,
Capillaria
spp., and
Shistosoma
spp. eggs were totally eliminated (100% decrease) and the
Taenia
spp. was absent from the first stage of composting. These results confirm the effectiveness of both dehydrating and composting processes on the removal of helminth eggs.
The present study is aimed at assessing the effectiveness of solar drying process in terms of helminth egg reduction in sewage sludge (SS) generated from an activated sludge wastewater treatment ...plant (WWTP) in Marrakesh city (Morocco). It is also engaged to highlight a synergic effect of liming (1% CaO) and solar drying on helminth egg reduction. The solar drying process was conducted for 45 days, in summer under a semi-arid climate in a pilot scale polycarbonate-based tunnel (2 m
3
). Before undergoing solar drying process, data showed an important load of helminth eggs including
Ascaris
sp.,
Schistosoma
spp
.
,
Capillaria
spp.,
Trichuris
spp
.
,
Ankylostome
spp
.
,
Toxocara
spp
.
, and
Taenia
spp
.
in limed sludge (LS) and non-limed sludge (NLS) (15.2 and 17.9 eggs/g, respectively). Ascaris eggs were the most abundant (11.2 and 13.5 eggs/g in LS and NLS, respectively). By the end of the solar drying process, a considerable removal of the total helminth eggs was recorded in LS and NLS (92.8% and 91.6%, respectively). A complete removal of
Schistosoma
spp
., Capillaria
spp
., Trichuris
spp
., Toxocara
spp
. and Taenia
spp
.
was noted in LS and NLS. In the case of
Ankylostome
spp
.
, data showed a total removal in LS and 81% in NLS; however, the final load is in agreement with the standards (0.4 egg/g). As for
Ascaris
spp
.
, neither liming nor solar drying process allowed a complete removal (91% and 90% in NLS and LS, respectively) and the final load (1.1 egg/g) does not fulfill the WHO requirements for an agricultural use. Principal component analysis (PCA) demonstrated a negative correlation between dry matter (DM) content (hence temperature) and helminth egg concentration. No significant synergic effect of liming and solar drying process was showed by statistical analysis. This is substantiating that temperature is the key parameter involved in helminth egg removal while undergoing solar drying of SS.
Africa’s lands are largely vulnerable and threatened by soil degradation and low water availability, especially in semi-arid and arid regions, limiting crop and livestock productivity and farmer ...livelihood options. Therefore, in African agricultural lands, adopting/improving measures that conserve soil and water resources is crucial. This review aims to provide an update on soil and water conservation (SWC) in terms of farmer practices and research actions and explore how SWC technologies and practices represent a pathway to build or re-establish soil health and enhance sustainable agriculture in Africa. It also aims to increase knowledge on best-fit SWC approaches. Soil conservation, which includes measures of controlling soil erosion and maintaining or improving soil fertility, is inseparable from water conservation. On agricultural lands, the two are typically co-addressed. Increasing plant biomass production through improved water, crop and soil management practices, and managing this biomass judiciously, have direct and indirect impacts on conserving soils and water resources, particularly in drylands. This study focuses on rainfed agricultural systems. We discuss the barriers and challenges to scaling up best-bet SWC technological and management options. Moreover, we show that options, such as Conservation Agriculture (CA), Agroforestry (AF), as well as integrated soil fertility management (ISFM) and field-scale rainwater harvesting (RWH), remain promising for the preservation and improvement of soil health in Africa’s farmlands and improving the resilience of agrosystems to climate change and variability as well as droughts.
Crop models have evolved over the past decade to incorporate more soil-related processes. While this may open avenues to support farmers regarding fertilization practices, it also widens the pitfalls ...related to model parametrization. Open-access georeferenced soil databases are often a solution for modelers to derive soil parameters. However, they can potentially add to model uncertainty depending on database resolution and the variability of the characteristics it contains. Fertimap is an online spatial database recently released in Morocco. In this study, we aim at assessing how Fertimap could support the use of crop model in the rainfed wheat production areas of Morocco. Data including local soil analysis, farmers’ practices, wheat biomass, and yield were collected on 126 farmers’ fields distributed across the rainfed wheat production area in Morocco from 2018 to 2020. Data were first used to parameterize, calibrate, and assess the model, using site-specific data to infer soil parameters. Then, the impact of soil data source on model uncertainty was assessed by rerunning the simulations while using alternatively locally measured soil inputs or inputs extracted from Fertimap. To disentangle the effect of data source from model sensitivity on model outputs, the model’s sensitivity to labile phosphorus, pH, and organic carbon parameters was also tested. The APSIM-wheat model was found to reasonably simulate wheat phenological stages, biomass, and yield. The comparison of model outputs using one or another source of soil data indicated that using Fertimap had no significant effect on the model’s outputs. This study provides the first assessment of the APSIM-wheat model for simulation of widely used wheat cultivars in Moroccan rainfed areas. It is also the first proof of the practical utility of Fertimap database for modeling purposes in Morocco. This preliminary study delivers a robust basis for model-assisted agricultural advising to take off in Morocco.
Abstract
In the context of climate change, in-season and longer-term yield predictions are needed to anticipate local and regional food crises and propose adaptations to farmers’ practices. ...Mechanistic models and machine learning are two modelling options to consider from this perspective. In this study, multiple regression (MR) and random forest (RF) models were calibrated for wheat yield prediction in Morocco, using data collected from 125 farmers’ wheat fields. Additionally, MR and RF models were calibrated both with or without remotely sensed leaf area index (LAI), while considering all farmers’ fields, or specifically to agroecological zoning in Morocco. The same farmers’ fields were simulated using a mechanistic model (APSIM-wheat). We compared the predictive performances of the empirical models and APSIM-wheat. Results showed that both MR and RF showed rather good predictive quality (normalized root mean square errors (NRMSEs) below 35 %), but were always outperformed by the APSIM model. Both RF and MR selected remotely sensed LAI at heading, climate variables (maximal temperatures at emergence and tillering), and fertilization practices (amount of nitrogen applied at heading) as major yield predictors. Integration of remotely sensed LAI in the calibration process reduced NRMSE by 4.5 % and 1.8 % on average for MR and RF models, respectively. Calibration of region-specific models did not significantly improve the predictive. These findings lead to the conclusion that mechanistic models are better at capturing the impacts of in-season climate variability and would be preferred to support short-term tactical adjustments to farmers’ practices, while machine learning models are easier to use in the perspective of mid-term regional prediction.
Agriculture is facing many challenges as climate change, drought, and salinity which call for urgent interventions to fast adaptation and diversification such as the introduction of new climate smart ...and stress tolerant crops such as quinoa. This study aims to introduce new high yielding quinoa cultivars conducted under several agronomic practices (rainfed, irrigation, and organic amendment) and to assess the technical and economic aspects related to quinoa seed production, transformation, and quality. Results obtained from agronomic trials clearly showed that International Center for Biosaline Agriculture cultivars recorded higher yields than locally cultivated seeds. Irrigation and organic amendment had a tremendous effect on quinoa productivity as it increased most of cultivar’s yield by more than three times compared with rainfed conditions. Production cost analysis showed that using mechanized production and processing practices combined with irrigation and organic amendment can reduce seed production and processing cost from 2.8 to 1.2 USD kg
−1
compared with manual production system under rainfed conditions. The diagnosis of the quinoa transformation pathways revealed different transformation levels, and the production cost increased with the level of transformation due to high cost of labor and raw material. Analysis of quinoa seeds showed that macronutrient content is mostly not affected by pearling process, while micronutrients content was significantly decreased in processed seeds. In addition, total saponin content was reduced to an acceptable level after using mechanical pearling compared with manual abrasion.
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