Effects of shortage of calcium and other cations on ⁴⁵Ca mobility, growth and nutritional disorders of tomato plants (<i>Lycopersicon esculentum</i>)

Abstract

Abstract Calcium mobility in tomato plants grown in sand‐ and water‐cultures with little calcium and other cations was studied using 45 Ca as a tracer. Radioautographs and 45 Ca activity measurements of plant parts showed that 45 Ca was “fixed” near the base (root or stem) of plants grown in low‐Ca nutrient solutions, compared with plants grown with adequate Ca in which 45 Ca was readily translocated to the tops. When plants were grown with little Ca and other cations (i.e. low K, Mg and micronutrients), 45 Ca was also readily translocated to the tops. Calcium stress during the fruiting stage caused serious blossom‐end rot of fruits, indicating that Ca absorbed by plants before fruiting was not readily available subsequently for fruit development. Leaf total‐Ca is not a reliable index for predicting fruit‐Ca deficiency in tomatoes.