MINERAL NEEDS OF BEGONIA X ELATIOR DURING THE GROWING PERIOD AND THE FLOWERING TIME

Two experiments were realized with the cv Aphrodite Radiant during winter and spring time with the same experimental design : four recycled nutrient solutions with increasing mineral N rates (11–17,5–22,5–41 meq/l in winter ; 9–13–17–27,5 meq/l in spring). The third experiment was managed with two other cv in fall without additional light, with a slow release fertilizer.

The total mineral needs (mg/plant) were the following during the growing stage : in winter : N, 582 ; P, 80 ; K, 502 ; Ca,219 ; Mg, 70 in spring : N,1091 ; P,207 ; K,1282 ; Ca,298 ; Mg,165

The mineral balance N/P/K/Ca/Mg goes from 1/0.14/0.86/0.38/0.12 in winter to 1/0.19/1.18/0.27/0.15 in spring. During the flowering time of a red cultivar, the balance becomes 1/0.18/0.83/0.50/0.28

It can be concluded that the mineral balances in the nutrient solutions must be choosen according to the growing period and that they keep relatively stable for P and K but increase for Ca and Mg during the flowering time.

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