Calcium Accumulation in Grasses in Relation to their Root Cation Exchange Capacity

In order to assess the role of root CEC on the accumulation of Calcium in roots or shoots, pot-culture experiments with wild grasses was carried out. The seven species of grasses used were Sporobolus diander (L.), Eleusine indica (L.) Gaertn., Heteropogon contortus (L.) P. Beauv. Ex Roem and Schult, Cynodon dactylon (L.) Pers., Panicum repens Jacq, Stenotaphrum dimidiatum (L.) Brongn. and Chloris barbeta Sw. These grasses were significantly different in their root cation exchange capacity (4.6 to 12.3 C mol (P+) kg-1; p<0.05) as well as in their average root biomass (10 to 121 g per plant; p<0.05)/shoot biomass (4 to 60 g per plant; p<0.05) while growing in same environments. Four treatments of calcium (0.20, 0.25, 0.30 and 0.37 g kg-1 of soil) were given to all these species against a control; each treatment was given in four split doses with a gap of about 10 days in between. Calcium in the roots and shoots of these grasses was assessed at the end of the experimental cultures. Negative correlations were found between average Ca accumulations in plant tissues and root cation exchange capacity at all treatment levels. The correlation patterns between root cation exchange capacity and Ca in roots and that in shoots were quite distinct. Experiments of these kinds can reveal exact relationships between root characteristics and mineral accumulations in plants, which will have applications in agriculture involving mixed crops.