Effects of salinity stress on seedlings growth, mineral nutrients and total chlorophyll of some tomato (Lycopersicum esculentum L.) cultivars

In this study, six cultivars of tomato (Lycopersicum esculentum L. var. Jaguar, Xewel, Nadira, Lindo, Mongal and Ninja) were evaluated. They were subjected to salt stress during vegetative growth. Three concentrations of salt solution 50, 100 and 200 mM NaCl and the control (Wacquant nutrient solution) were used in irrigation. The total chlorophyll, the dry weight of seedlings (roots dry weight, stems dry weight and leaf dry weight), the plant height and the mineral nutrient concentrations (Na+, K+ and Ca2+) were determined. The results showed that the salt treatments increased significantly Na+ concentrations in roots, stems and leaves of plants, whereas K+ and Ca2+ concentrations and K+/Na+ selectivity ratio of plants were decreased in all tomato cultivars. The results also revealed after six weeks of salt treatments that the dry weight partitioning and the plant height decreased significantly in Jaguar, Xewel, Nadira and Mongal with increasing salinity. Jaguar, Xewel, Nadira and Mongal can therefore be considered as salt-sensitive cultivars which tolerance level ranges from 0 to 50 mM NaCl. The Lindo and Ninja plant height was less affected by salt stress than the four other cultivars. In Ninja, the moderately salt-tolerant cultivar, the growth parameters were significantly reduced at 100 mM NaCl. The supply of mineral nutrient solution with NaCl did not affect significantly leaf total chlorophyll content and plant organs dry weight of Lindo at 100 mM NaCl suggesting that it was relatively more tolerant in saline medium than other cultivars studied. The Lindo cultivar could be cultivated in environments with relatively moderate salinity.Keywords: Growth, Lycopersicum esculentum, tolerance, mineral nutrients, plant organsAfrican Journal of Biotechnology Vol. 9(33), pp. 5366-5372, 16 August, 201

Effects of some physical and chemical characteristics of soil on productivity and yield of cowpea (Vigna unguiculata L. Walp.) in coastal region (Cameroon)

Studies were conducted to assess the response of cowpea (Vigna unguiculata L. Walp) to some physical and chemical characteristics of soil in coastal region (Cameroon). The cowpea variety used in this trial was Tsacre, planted at a spacing of 80 cm × 80 cm. The experimental design was a randomized complete block comprising of five plots with three replicates. Productivity parameters (dry weight aerial parts, roots dry weight, abortion seeds rate, number of flowering per plant, flowering rate) and yield components (number of seeds per pod, number of pod per plant, grain yield, pod yield and weight of 1000 seeds) were determined. Soil samples were taken randomly from depths of 0 - 30 and 30 - 60 cm before seeds sowing. The results showed that the plot with the highest percentage of sand (71.80%), the lowest percentage of clay (21.00%) and silt (7.20%) and with the highest amount of organic matter (10.26%), exchange potassium (0.36 g Kg-1), calcium (0.49 g Kg-1) and magnesium (0.46 g Kg-1) increased significantly (

Mineral nutrient status, some quality and morphological characteristics changes in peanut (Arachis hypogaea L.) cultivars under salt stress

Peanut (Arachis hypogaea L.) is considered to be one of the most important crops which thrive in newly reclaimed sandy soils as a leguminous crop of high nutritive value and a source of edible oil. Our study tested the effects of different salt levels on mineral nutrient partitioning (Na+, K+, Mg2+, Ca2+, P and N) and some quality (dry weight and leaf relative water content) and morphological (plant height, number of leaves) characteristics of peanut commercial cultivars. Four peanut cultivars (Mbiah, Ngondo, Pyrieur and Vanda) were used in this experiment. Three concentrations of salt solution including 50, 100 and 200 mM NaCl and the control (Wacquant nutrient solution) were used in irrigation. The pot experiment was arranged in completely randomized design with four replicates. The leaf relative water content (LRWC) provoked by the salinity in nutrient solution decreased from 85.08 to 83.43%, 87.82 to 85.30%, 85.81 to 78.20% and 85.90 to 79.70% in Mbiah, Ngondo, Pyrieur and Vanda cultivars respectively. The results showed that the salt stress reduced significantly (p<0.05) the plant height in Pyrieur cultivar from 40.49 to 21.45 cm, the number of leaves from 11.2 to 7.0, the dry weight of roots from 0.15 to 0.11 g Plant-1, the dry weight of stems from 0.37 to 0.15 g Plant-1 and the dry weight of leaves from 0.46 to 0.19 g Plant-1. Similar results were obtained in Vanda cultivar where the supply of nutrient solution with salinity reduced significantly (p<0.05) the plant height from 38.26 to 26.30 cm, the number of leaves from 12.5 to 7.5, the dry weight of roots from 0.14 to 0.03 g Plant-1, the dry weight of stems from 0.36 to 0.12 g Plant-1 and the dry weight oh leaves from 0.46 to 0.19 g Plant-1. The results also revealed that K+, Mg2+, Ca2+, P, N, K+/Na+ and Ca2+/Na+ uptake of peanut plant organs were significantly (p<0.05) reduced with increasing salinity in Pyrieur, Vanda and Mbiah except for total N accumulation in plant organs of Mbiah. The plant height, the number of leaves, the dry weight and the mineral nutrient uptake were not significantly (p>0.05) reduced under salt stress in Ngondo plant organs except at high salt-treated (200 mM NaCl). The Ngondo cultivar was observed to have relatively higher tolerance on average of all growth parameters and mineral nutrient status than others. This finding suggested that the Ngondo cultivar could be used to highlight the newly salt cultivated sandy soils in arid, semi-arid regions and similar environments across Cameroon.Key words: Arachis hypogaea, growth parameters, mineral nutrient, plant organs, salt stress

Effects of salinity and drought on growth, ionic relations, compatible solutes and activation of antioxidant systems in oleander (Nerium oleander L.)

[EN] Nerium oleander is an ornamental species of high aesthetic value, grown in arid and semi- arid regions because of its drought tolerance, which is also considered as relatively resistant to salt; yet the biochemical and molecular mechanisms underlying oleander¿s stress toler- ance remain largely unknown. To investigate these mechanisms, one-year-old oleander seedlings were exposed to 15 and 30 days of treatment with increasing salt concentratio ns, up to 800 mM NaCl, and to complete withholding of irrigation; growth parameters and bio- chemical markers characteristic of conserved stress-response pathways were then deter- mined in stressed and control plants. Strong water deficit and salt stress both caused inhibition of growth, degradation of photosynthetic pigments, a slight (but statistically signifi- cant) increase in the leaf levels of specific osmolytes, and induction of oxidative stress¿as indicated by the accumulation of malondialdehyde (MDA), a reliable oxidative stress marker ¿accompanied by increases in the levels of total phenolic compounds and antioxidant fla- vonoids and in the specific activities of ascorbate peroxidase (APX) and glutathione reduc- tase (GR). High salinity, in addition, induced accumulation of Na + and Cl - in roots and leaves and the activation of superoxide dismutase (SOD) and catalase (CAT) activities. Apart from anatomical adaptations that protect oleander from leaf dehydration at moderate levels of stress, our results indicate that tolerance of this species to salinity and water deficit is based on the constitutive accumulation in leaves of high concentratio ns of soluble carbohydrates and, to a lesser extent, of glycine betaine, and in the activation of the aforementioned antiox- idant systems. Moreover, regarding specifically salt stress, mechanisms efficiently blocking transport of toxic ions from the roots to the aerial parts of the plant appear to contribute to a large extent to tolerance in Nerium oleanderThis work was financed by internal funds of the Polytechnic University of Valencia to Monica Boscaiu and Oscar Vicente. Dinesh Kumar’s stay in Valencia was financed by a NAMASTE fellowship from the European Union, and Mohamad Al Hassan was a recipient of an Erasmus Mundus pre-doctoral scholarship financed by the European Commission (Welcome Consortium).Kumar, D.; Al Hassan, M.; Naranjo Olivero, MA.; Agrawal, V.; Boscaiu, M.; Vicente, O. (2017). Effects of salinity and drought on growth, ionic relations, compatible solutes and activation of antioxidant systems in oleander (Nerium oleander L.). PLoS ONE. 12(9). doi:10.1371/journal.pone.0185017Se018501712

Salinity effect on seedling growth, water, sodium and potassium distributions in the mangrove species (Avicennia germinans L. (Avicenniaceae)) in semi controlled conditions.

The effect on plant growth of NaCl concentrations in soil, under semi-controlled conditions, water content and monovalent cations (Na+ and K+) distributions in seedlings of Avicennia germinans were studied. After 4 weeks of growth, results show that NaCl affected leaf growth more than roots and stems. For the two lower vegetal organs, 100 mmoles of NaCl brought about a significant increase in plant growth. A high retention rate of Na was noted in seedling epicotyl axes, contributing in delaying young leaves proliferation and thereby, preventing the toxic effects of this ion. Mature leaves exhibited good adaptative behavior toward salinity stress by increasing succulence due to absorption of large quantities of water and K+ in leaves. Potassium uptake in leaves was not found to be affected by NaCl concentration. As a consequence, monovalent cations adsorption resulted in an increase in the water contents of the plant organs. The high accumulation of K+ in leaves of A. germinans show that this ion was the major element responsible for osmotic adjustment in leaf cells.L\'effet de différentes concentrations du milieu en NaCl sur la croissance de la plante, l\'état hydrique et la distribution des cations monovalents (Na+ et K+) au niveau des organes de Avicennia germinans a été étudié en conditions semi-contrôlées. Après 4 semaines de culture, les résultats montrent que le NaCl améliore significativement plus la croissance des feuilles que celle des racines et des tiges. Pour ces derniers organes, une concentration de 100 mmoles de NaCl a entraîné une meilleure croissance. Une forte rétention de Na a été observée au niveau des axes épicotylés des plantules, contribuant à réduire l\'envahissement des jeunes feuilles et par conséquent, éviter les effets toxiques de cet ion. Les feuilles plus âgées s\'adaptent aux conditions de salinité, à travers l\'augmentation de la succulence, due à une absorption massive d\'eau et de K+. L\'approvisionnement en K+ des feuilles n\'a pas été affecté par la présence de NaCl dans le milieu. Par conséquent, l\'absorption des cations monovalents Na+ et K+ a entrainé une augmentation de la teneur en eau des organes étudiés. La forte accumulation de K+, au niveau des feuilles, montre que chez A. germinans, cet ion est le principal élément responsable de l\'ajustement osmotique des cellules foliaires. Keywords: Mangrove, Avicennia germinans, salinity, ionic transport, CameroonAgronomie Africaine Vol. 19 (3) 2007: pp. 263-27

Parasitisme des champs semenciers de cacaoyers par les Loranthaceae dans la localité de Nkoemvone (sud Cameroun)

 Objectif : le présent travail consiste à rechercher les méthodes de lutte adéquates contre le parasitisme des Loranthaceae dans les champs semenciers de la SODECAO à Nkoemvone, au Cameroun.Méthodologie et résultats : l’étude a consisté à dénombrer les différentes espèces de Loranthaceae qui parasitent les champs semenciers, les pieds de cacaoyers infestés et les touffes de parasites rencontrés sur ces arbres, afin de déterminer le taux et l’intensité du parasitisme des cacaoyers et le comportement des différents clones vis-à-vis de l’attaque des  Loranthaceae. Les résultats obtenus montrent que Cinq Loranthaceae attaquent les champs semenciers, le niveau d’infestation varie suivant les différents clones, Phragmanthera capitata est la Loranthaceae la plus abondante ; le niveau de parasitisme des cacaoyers est plus important chez les cacaoyers de diamètre moyen.Conclusion et application des résultats : pour une amélioration des récoltes par les paysans, il est urgent de rechercher les méthodes de lutte appropriées contre le parasitisme des Loranthaceae. En attendant uneméthode de lutte efficace, les clones ICS 46 et UPA 146 résistants au parasitisme, peuvent être utilisés pour l’extension des champs semenciers et la distribution aux paysans.Mots clés : Loranthaceae, semenciers, cacaoyers, clones, parasitisme, Nkoemvone  Objective: The present work consists in looking for appropriate control methods against the parasitism of Loranthaceae in the seed fields of the SODECAO to Nkoemvone, in Cameroon.Methodology and results: The study consisted in counting the various species of Loranthaceae which live as parasites on the seed fields, on the feet of infested cacao trees and to determine the rate and the intensity ofthe parasitism of cacao trees and the behaviour of the various clones towards the attack of Loranthaceae. The obtained results show that five Loranthaceae attacked the seed fields, the level of infestation varied according to the various clones, Phragmanthera capitata was the most abundant Loranthaceae; the level of parasitism of cacao trees is more important at the cacao trees of average diameter.Conclusion and application of the results: for an improvement of the harvest by the farmers, it is urgent seek appropriate control methods suited against the parasitism of Loranthaceae. Pending an effective controlmethod, clones ICS 46 and UPA 146 resistant of parasites can be used for the extension of fields and seed distribution to farmersKey words: Loranthaceae, seed fields, cocoa, clones, parasitism, Nkoemvon

Effets de la salinite sur la croissance, la distribution ionique et l\'etat hydrique d\'une glycophyte tolerante: Gossypium hirsutum (Malvaceae)

No Abstract.Journal of the Cameroon Academy of Sciences Vol. 6 (3) 2006: pp. 167-17

Changes in growth and nutrient uptake in response to foliar application of sodium and calcium chloride in cowpea cultivars (Vigna unguiculata L. Walp)

In this study, the effects of NaCl and CaCl2 on growth and nutrients uptake of cowpea (Vigna unguiculata L. Walp cvs. Mouola GG; Mouola PG, Garoua GG, Garoua PG and Tsacre) were investigated. Three treatments [0 (unsprayed), 50 mM NaCl or 50 mM CaCl2] were adopted, with five replications. NaCl and CaCl2 were applied as foliar spray twice a week during 30 days after sowing. Application of NaCl resulted in significant decreases in plant height, dry weights of root and shoot of Garoua GG, Mouola PG and Tsacre compared to Garoua PG and Mouola GG cultivars, while those growth parameters were significantly reduced under CaCl2 treatment in all cowpea cultivars except Mouola PG. K+, Ca2+ and Mg2+ contents decreased under NaCl stress in leaves of Garoua PG and Mouola GG, but no significant changes were observed in those of Garoua GG, Mouola PG and Tsacre. The main strategy of salt tolerance in Mouola GG and Garoua PG seems to be as a result of increased osmotic adjustment through the accumulation of Na+ in leaves while in salt sensitive Mouola PG, Garoua GG and Tsacre, the osmotic adjustment may be due to the accumulation of inorganic ions (K+, Ca2+ and Mg2+) in leaves, contributing to the maintenance of water uptake and cell turgor, allowing for physiological processes. In the analysis of growth parameters measured, the results suggested that Mouola GG and Garoua PG cultivars were relatively more tolerant to salinity than others, suggesting that those cultivars could be cultivated in the environment with varying salinity. CaCl2 treatment significantly increased growth parameters and nutrients uptake specially Ca2+ in Mouola PG cultivar, suggesting that it could grow and develop on calcareous soils.Keyword: Foliar spray, growth, nutrients uptake, saline and calcareous soils, Vigna unguiculata.African Journal of Biotechnology, Vol 13(47) 4382-438

Influence des aports mod&#233r&#233s d'engrais sur la valeur nutritionnelle de Manihot esculenta Crantz. (Euphorbiaceae)

No Abstract.Cameroon Journal of Experimental Biology Vol. 2 (2) 2006: pp. 62-6

Germination et accumulation des métabolites chez les plantules de légumineuses cultivées sous stress salin

Les effets de la salinité sur le comportement physiologique des graines, feuilles et tiges de cinq légumineuses ont été évalués afin d\'identifier des critères précoces de sélection des espèces végétales tolérantes au sel. Quatre niveaux de salinité (0, 50, 100 et 200 mM de NaCl) ont été testés. Au bout de 4 semaines, trois séries de 7 plantes ont été prélevées dans chaque milieu de culture en vue d\'évaluer les teneurs en lipides, protéines et proline. Ainsi, l\'apport de NaCl a entraîné une baisse significative des teneurs en lipides et du taux de germination chez toutes les espèces étudiées. Cependant cet effet dépressif du sel a été plus marqué chez les deux glycophytes sensibles (Phaseolus vulgaris et Glycine max ) ; leur vitesse de germination étant fortement ralentie à partir de 3 g/l de NaCl avec des seuils critiques d\'inhibition à la germination à 9 et 12 g/l de NaCl respectivement. Toutefois ce seuil critique a été au-delà de 21 g/l pour Mucuna poggei (halophyte facultative), Phaseolus adenanthus (halophyte) et Vigna unguiculata (glycophyte moyennement tolérante). L\'effet dépressif du sel a été moins marqué sur la croissance en hauteur des tiges chez P. adenanthus, M. poggei et V. unguiculata excepté chez ces deux dernières espèces à 200 mM. L\'apport de sel a entraîné une accumulation des protéines et de proline au niveau des feuilles chez M. Poggei, P. adenanthus et V. unguiculata comparativement à G. max et P. vulgaris. Le taux de germination et l\'accumulation des protéines et proline au niveau des feuilles pourraient être utilisés comme critères précoces de sélection des légumineuses tolérantes à la salinité.In order to determine physiological criteria of early selection for salt tolerant leguminous plants, effects of NaCl concentrations on physiological behaviour of seeds, leaves and stems of five leguminous plants were evaluated. Plants were submitted to 4 levels of salt stress at the roots (0, 50, 100 and 200 mM of NaCl). After four weeks, lipids, proteins and proline contents were determined in each medium on 7 randomly sampled plants. Results showed that sodium chloride had an underrating effect on growth of stems and seed germination of the species studied. The germination rates of seeds of Glycine max and Phaseolus vulgaris (sensitive glycophytes) were affected from 3 g/l of NaCl, with critical thresholds at 9 and 12 g/l respectively. In contrast, critical thresholds with Mucuna poggei (facultative halophyte), Vigna unguiculata (moderately tolerant glycophyte) and P. adenanthus (natural halophyte) was found to be above 21 g/l. The reduction of stems growth rate were not significant in P. adenanthus whereas in M. poggei and V. unguiculata this inhibition was observed just when nutritive solutions were enriched with 200 mM. The lipid contents were reduced in all the species under salt stress, whereas proteins and proline contents in the leaves were substantially increased in tolerant species (M. poggei, P. adenanthus, and V. unguiculata). In contrast, proteins and leaf proline contents were negatively affected by salt concentration to G. max and P. vulgaris. Seed germination, proteins and proline could be used as physiological criteria of early selection for salt tolerant leguminous plants Keywords: Stress salin, légumineuses, NaCl, accumulation des métabolites, CamerounAgronomie Africaine Vol. 20 (2) 2008: pp. 129-13