Soil salinity has a negative impact on crop production over the world. The effect of salt stress on growth, chlorophyll content, mineral distribution, biochemical constituents and non-enzymatic antioxidant compounds of white yam (Dioscorea rotundata (L) var. gana) cultivar regularly consumed in Cameroon were investigated. Plants were subjected to four different levels concentrations of NaCl (0, 50, 100 and 200 mM), with 0 mM NaCl as a control. The supply of intake doses of NaCl in the culture medium significantly (P < 0.001) decreased the dry biomass (roots and shoots), growth parameters (number of leaves, noose diameter, leaf area and stem height) and chlorophyll contents from 100 mM NaCl. Mineral elements (K, Ca and Mg) and K/Na ratio significantly (P < 0.001) decreased in roots and shoots with increasing salinity. The higher sodium (Na) concentrations were recorded in shoots than in roots. The different biochemical constituents (proline (PRO), total soluble carbohydrates (CH), soluble proteins (PR) and total free amino acids (FAA)) and non-enzymatic antioxidants compounds (total phenolic (TP) and flavonoids (FLA) contents) significantly (P < 0.001) increased from 50 mM NaCl. The main strategy in cv. gana seems to increase osmotic adjustment through high accumulation of CH, PR, FAA and PRO in the leaves and they could eventually be considered as biochemical indicators of early selection and osmotic adjustment ability for salt tolerant plants. The gana variety could be encouraged to be planted on salt affected soils for the better development in salty areas.

Influence des sols salins et calcaires sur la croissance, la nutrition minérale et les composantes agronomiques du niébé dans trois zones agro écologiques du Cameroun

Salt stress negatively impacts plant physiology, metabolism and productivity.The effects of mycorrhizal biofertilizer on the biochemical constituent, nutrient uptake, chlorophyll content, growth and agronomic parameters of American Yam bean (Pachyrhizus erosus L.) under saline conditions were investigated. Seeds were planted in polythene bags previously filled with sand, 50 g of Biofertilizer and supplied with a nutrient solution for six weeks in a completely randomized design in a greenhouse. Plants were subjected to NaCl concentrations (0, 50, 100 and 200 mM) with 0 as control. The concentrations 0 and 50 mM NaCl were tested on the farm for five months. Plots were arranged in a randomized block design. The number of flowers per plant, flowering time, number of pods per plant, yield and harvest index were evaluated. The results in the greenhouse showed that the stem height, leaf area, the number of leaves, noose diameter, dry biomass and chlorophyll content decreased significantly (P<0.01) from 100 mM NaCl. Mg, Ca and K significantly (P<0.001) decreased in plant organs with the supply of intake doses of NaCl in the culture medium. The different metabolites (Total soluble proteins, Proline, Total free amino acids, Total soluble carbohydrates and Total phenolic contents) increased significantly (P< 0.001) from 50 mM NaCl. The findings indicate that the accumulation of AMF positively influenced the growth and agronomic parameters of American yam bean under salinity.Their use alleviated the toxicity of NaCl, improved crop productivity and could be encouraged for better development of salinity affected areas.

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