Abstract
Calcium (Ca) is an important macronutrient for soybean production, and its absorption and translocation are influenced by environmental factors. Therefore, the effects of 12 and 16 h photoperiods with and without water stress during the seed-filling stage of soybean on the distribution of Ca was studied by using the radioisotope (45Ca) as a tracer in leaves, petioles, and stem within nodes. Univariate and multivariate analyses (Manova) showed the main effects of photoperiod, water stress, and plant tissues on Ca distribution to be highly significant (p<<0.001) . The 16 h photoperiod increased the Ca concentration in top leaves compared with the 12 h photoperiod. Water stress significantly (p<0.001) modified the pattern of Ca distribution and reduced its concentration in plant tissues within nodes irrespective of photoperiod.
