Effet améliorateur d'un apport extérieur de calcium et de potassium sous différentes formes sur la tolérance à la salinité de l'amarante (Amaranthus cruentus L.)

Aims: The present study was carried out to access the salt tolerance level of nine amaranth (Amaranthus cruentus) mutant lines selected from Benin cultivar ‘Locale’ at young plants stage in comparison with the cultivar ‘Locale’ used as control. Study Design: The experiment was laid out as a Completely Randomized Design with three replications. Place and Duration of Study: The experiment was carried out in a screening house at University of Abomey-Calavi, City of Abomey-Calavi, Republic of Benin from May to June, 2020. Methodology: Three-weeks old plants of the nine stable mutant lines and the control cultivar ‘Locale’ were planted in pots containing a mixture of potting soil and sand. NaCl concentrations: 0; 100; 150 and 200 mM were given by irrigation once in two days Plant growth parameters were evaluated after two weeks. Results: Salt effect caused a reduction of young plant growth whatever the growth parameter considered with a significant disparity (p=.001) among the genotypes. Growth of the control cultivar, lines 1, 11 and 15 was most affected under salt stress whereas that of lines 18; 23 and 16 was least affected. A significant difference (p=.01 or p=.001) was observed among the salt tolerance index of genotypes. The highest salt tolerance index was observed in the line 23 followed by lines 18 and 2; and the lowest in line 15 followed by line 17, line 10 and the control cultivar. Conclusion: Some variability was observed among lines for their salt resistance. Lines 23, 18 followed by line 2 appeared as the most salt resistant types whereas line 15, followed by lines 17, 10 and the control cultivar were the most salt sensitive. Thus, lines 23, 18 and 2 are promising for salt affected areas. Further studies are necessary to determine the physiological and biochemical mechanisms involved in the lines’ salt resistance.

Aims: This research has as objective to evaluate the effect of NaCl salt stress on African eggplant plant growth and to determine the implication of the accumulation of Na+, proline and soluble sugars and the reduction of K+ in the detrimental effect of NaCl in the growth of this plant species. Study Design: The experiment was laid out in a Completely Randomized Design (CRD) having five treatments and three replications. Place and Duration of Study: The experiment was carried out in screening house under natural  conditions at the International Institute of Tropical Agriculture, Commune of Abomey-Calavi. Republic of Benin from June to august 2022. Methodology: Five NaCI concentrations (0, 30, 60, 90 and 120 mM) were used to irrigate four weeks old plants for two weeks. Plant growth, sodium (Na), potassium (K), proline, and soluble sugars contents of leaves and roots were determined at the end of the experiment. Results: Salt stress induced a significant reduction (P = .001) in shoot and root growth from 30 : 60 or 90 mM NaCI according to the growth parameter but had no impact on shoot water content. Leaf and roots Na+ contents significantly increased (P = .001) under salt stress whereas K+ content deoreased significantly (P = .05) only in root. Na change was observed for proline and soluble sugars contents in both leaf and root. Conclusion: Salt stress reduces the growth of plants of African eggplant due mainly to Na+ ion toxicity. The ionic selectivity ratio (K+/ Na+) rather than the K+ ion content plays an important role in the response of plants of African eggplant to salt stress. Proline and soluble sugars accumulation appeared not to intervene.

Amaranthus species are of underutilized orphan crops grown in tropical and sub-tropical regions of the world. Benin’s most appreciated Amaranthus cruentus L. «local» cultivar is susceptible to saline stress. This study aimed to create genotypes agronomically, at least, as good as the «local» cultivar and useful for further saline tolerance breeding using mutation breeding. The morphological diversity among 19 gamma-irradiated A. cruentus mutant lines and «local» cultivar (control) were investigated, through a randomized complete block design with three replications, using 18 phenotypical traits (12 quantitative and 6 qualitative). The results show that among the six qualitative traits, only terminal inflorescence shape was discriminant. However, permutation analysis of variance revealed significant variability in quantitative traits: leaf width (CV=19%), Branches length (CV=47%), plant height (CV=25%), stem diameter (CV=29%), number of branches (21%) number of leaves (CV=25%). Multivariate analysis of quantitative traits showed the first two principal components contributing to 78.30% of observed variability. Correlation analysis revealed the significance of number of leaves, number of branches, plant height and leaf width for selecting better genotypes for biomass production. Mutant lines L1, L2, L6, L16, L18 and L23 showed high performances for traits cited above and could, therefore, be a good source of genes.