Magnesium deficiencies and toxicities may decrease fruit yield and quality. In two cultivars of apple
(Malus pumila Mill.), fruit magnesium concentrations were correlated negatively with fruit color,
whereas fruit potassium concentrations were positively correlated with fruit color
(48). The effects
of magnesium on apple fruit quality may have been due to antagonistic effects on potassium uptake
and accumulation. In tomato, even though increasing magnesium fertilization rates did not affect
total shoot dry weight, overall fruit yield decreased with increased magnesium fertilization supply
from 0.5 to 10 mM
(37).