MICRONUTRIENT TESTING IN ARTIFICIAL MIX SUBSTRATES

A greenhouse experiment was conducted to determine if analyzing the substrate or the leaf tissue grown in it for their micronutrient content, would provide a more reliable assessment of the micronutrient status in peat-vermiculite soil mixes in relation to tomato production.

Three levels of Mn and three levels of Zn at 1:3:9 ratios were applied to the substrate with three replications.
Tomato plants were grown through maturity.
The substrate was sampled four times and the tomato leaves three times, during the growing season.
Finally, the distribution of Mn and Zn was determined in the roots, stems, leaves, and fruit.
In Zn treated substrates, Zn in roots had 1:3:9 and in Mn treated substrates, Mn in roots had 1:3:50 ratios.
In stems, Zn concentration was very high and Mn concentration was very low.

The double acid (0.05NHCl and 0.025NH₂SO₄) and DTPA extracts of the substrate and the nitric-perchloric acid digests of plant tissue were analyzed with an atomic absorption spectrophotometer.

The model using the four substrate samplings extracted for Zn and Mn by DTPA and the three leaf samplings analyzed for Zn predicted yield with a R²=0.84. A model using the first and fourth substrate samplings extracted for Zn and Mn by DTPA and the first leaf samplings analyzed for Zn predicted yield with a R²=0.70. DTPA was a more sensitive extractant for Zn and Mn than the double acid (DA).

Symposium on Substrates in Horticulture other than Soils In Situ

D.K. Markus, J.E. Steckel, J.R. Trout

https://doi.org/10.17660/ActaHortic.1982.126.27