Soybean [Glycine max (L.) Merr.] plants produce fewer and lower quality see
ds when grown in conditions that decrease seed Ca concentration. Indetermin
ate soybean was gown in modified hydroponic culture to ascertain the effect
s of Ca deficiency on leaf dry matter, seed production and elemental concen
tration, and the effect of pod position on seed elemental concentration in
1992 and 1993. Treatments consisted of 2.0 (Control), 0.2 (Low), 0.1 (Very
Low) mM Ca in the nutrient media. Some Control plants were switched to Low
or Very Low (Con/L, VL) Ca levels at beginning seed growth stage (R5), and
some plants grown at the Very Low Ca level were switched to the Control (VL
/Con) Ca level at R5. At harvest, plants were divided into four sections: t
op-third (T/3), middle-third (M/3), and bottom-third (B/3) of the mainstem
and branches (Br). Low and Very Low treatments produced 65 and 10% as much
seed mass, respectively, as Control in both years. Low and Very Low treatme
nts retained significantly less total leaf dry matter at R5 in both years.
Seed Ca levels were 25 to 300% higher in treatments that included the Contr
ol Ca level during any part of reproductive growth compared to other treatm
ents in both years. Seed Ca concentration was highest in the T/3 and Br sec
tions in both years. Germination was reduced in treatments not including th
e Control solution during part of the reproductive growth period in both ye
ars. Decreased Ca levels in the nutrient medium reduced soybean leaf dry ma
tter during seed fill, seed production, seed Ca concentration, and seed ger
mination, and increased the incidence of seedling disorders such as watery
hypocotyl and epicotyl necrosis.