“…A reduction in quantity of chloroplasts, number of lamellar membranes, and starch within deficient plants is morphological evidence of reduced photosynthetic activity. A reduction in starch content as observed in this study seems to be one of the earliest symptoms of Mn deficiency and supports findings of Eltinge (1941); Vesk, Possingham, and Mercer (1966); and Cheniae and Martin (1968). Since chlorophyll content is not a true indication of photosynthesis with no obligatory linear relationship (Ruck and Bolas, 1954;Cooper and Girton, 1963;Crang and Noble, 1974), low photosynthetic rates may be a consequence of the absence of Mn, which is known to participate in the 02-evolving step of the light reaction (Kessler, 1955;Eyster et al, 1958;Cheniae and Martin, 1967;Heath and Hind, 1969) rather than a decrease in chlorophyll content.…”