EFFECT OF LOW POTASSIUM REGIMES ON SOME SALT-TOLERANT AND DROUGHT-TOLERANT LINES OF PEARL-MILLET

The effect of K deficiency on three salt- and drought-tolerant lines of pearl millet (Pennisetum glaucum A. Br.), Kitui local, KAT/PM-2 and Selection II was studied in a pot experiment. Plants of these lines were treated with 235 (control), 117.5, 58.8, 29.4, and 14.7 mg L-1 K in Hoagland's nutrient solution. Of the three lines, Selection II was the highest, Kitui local the lowest and KAT/PM-2 intermediate in shoot and root mass. Analysis of tissue K showed that Selection II had high K+ concentrations in the leaves and low concentrations in the roots compared with the other two lines. This relatively greater translocation of K+ from roots to leaves could explain this line's vigorous growth under K-deficient regimes. By contrast, Kitui local was not able to efficiently translocate K+ from roots to leaves, a factor which may account for its greater relative sensitivity to K-deficient conditions. The moderate growth performance of KAT/PM-2 could be related to its moderate uptake of K+ in its leaves and roots. It is concluded that Selection II is the most K-efficient of the lines examined in this study and can be used for salt affected and drought-prone sandy soils naturally low in potassium.