EFFECT OF LEAD INCREMENTS ON THE YIELD AND LEAD CONTENT OF TOMATO PLANTS

One seedling of tomato was planted in each pot containing 3 1.c. of either clay, CaCO3-rich, sandy soils or washed sand. Increments of Pb(NO3)2 were added to the soil or sprayed on the plants of the washed sand pots. Burning of leaves' margins were noticed on the sprayed plants. The fruits' fresh and dry weights significantly decreased with Pb increments and exponential equations were used to express this relationship. Comparing the slopes of the equations indicated that the Pb effect on yield of plants grown on clay: CaCO3-rich: sandy soils is equivalent to 1:0.63:0.66, respectively. The correlation coefficients between Pb concentration in the shoots and the weight of tomato fruits were -0.869, -0.944, -0.911 and -0.845 for the plants grown on the three soils and washed sand, respectively. Straight line equations were established to express the relation between Pb concentration in the shoots and in the fruits.