Effect of salinity on the physiology of peanut variety 73-33 (Arachis hypogaea L.)

Abstract

Peanut (Arachis hypogaea, L.) is an annual papilionaceous oilseed legume cultivated on nearly 25 million hectares in tropical and temperate zones due to its remarkable plasticity to temperature and water requirements. In Senegal, peanut is produced in rural areas where they are the main source of agricultural income. Variety 73-33 is cultivated in the river valley and the groundnut basin is subject to the influence of salinization affecting four of Senegal's ecogeographic zones. Studies conducted with randomized full-block experimental set-up in the laboratory and under semi-controlled greenhouse conditions have shown the effect of different concentrations of NaCl on the peanut variety 73-33: 0mM; 25mM; 50mM; 100mM; 200mM; 300mM; 400mM; 500mM for germination and 0mM; 25mM; 50mM; 100mM for growth growth and chlorophyll production. The parameters which were measured are: the germination rate (ten days after sowing), the number of nodules, the number of gynophores, the dry biomass and the production of chlorophyll at twenty, forty and seventy-five days after sowing. Germination is significantly negatively affected from 400mM. Twenty days after sowing there is a significant difference between the control and the other treatments for the production of chlorophyll a (Chla) only. Forty days after sowing, the production of chlorophyll a and total chlorophyll shows a very highly significant difference between all the treatments. The dry biomass only shows a significant difference from 100mM. Seventy-five days after sowing, the dry biomass and the number of gynophores are significantly reduced by the salinity from 25mM.