Articles
EFFECTS OF PH VALUE AND MN APPLICATION ON YIELD AND NUTRIENT ABSORPTION WITH ROCKWOOL GROWN GERBERA (REFEREED)
Average pH values between 6.7 and 5.6 were realized in the rockwool slabs by different quantities of NH4 in the nutrient solution added to the crop.
Furthermore three Mn levels were realized in the nutrient solution, viz. 0, 7.5 and 15 μmol l-1. Two cultivars were grown, viz.
Amber and Joyce, highly and less sensitive to chlorosis, respectively.
With lowering of the pH the chlorosis was strongly suppressed.
Increasing Mn supply also reduced the chlorosis.
However, this was only the case with the highest pH value.
The pH strongly affected the number of flowers harvested as well as the flower weight.
The number of flowers with the lowest pH value was 26 and 16% higher than those with the highest pH value for the cultivars Amber and-Joyce, respectively.
For the flower weight these percentages were 24 and 10. The Mn application had no significant effect on the flower production.
The effect of the pH on the absorption of macro elements was small and unimportant, but the effect on the micro nutrient absorption was substantial.
The Mn application only affected the Mn absorption.
The Mn contents in the plant tissues were closely correlated with those in the rockwool slabs.
Recommendations are given for the Mn application in relation to the pH value in the root environment.