Articles
Quantifying the effects of fifteen floriculture species on substrate-pH
Article number
1266_47
Pages
337 – 344
Language
English
Abstract
Floriculture species differ in their effect on substrate-pH and the resulting substrate micronutrient availability in container production.
The objective was to quantify effects of floriculture plant species on substrate-pH. In a growth chamber factorial experiment, 15 floriculture species were grown in 70%:30% by volume peat:perlite substrate and fertilized with nutrient solutions containing 100 mg L‑1 N at NH4+-N:NO3–-N nitrogen ratios of 0:100, 20:80, or 40:60. After 33 days, species and solution type effects on substrate-pH and estimated mEq of acid or base produced were evaluated.
Final substrate-pH ranged from 4.83 for geranium (Pelargonium × hortorum Bailey L.H.) in 40:60 solution to 6.58 for lisianthus in 0:100 solution, compared to an initial substrate-pH of 5.84. This change in substrate-pH corresponded with a net mEq of acid or base produced g‑1 tissue dry mass gain (NMEQ) ranging across solutions and species from 1.47 of base for lisianthus (Eustoma grandiflorum Salisb.) in the 0:100 solution to 2.10 of acid for coleus (Solenostemon scutellariodes L.) in the 40:60 solution.
With the 0:100 solution, species that took up more anions than cations into plant tissue tended to have a more basic effect on substrate-pH, as would be expected to maintain electroneutrality.
Data were used to estimate the percent NH4+-N of total N in a nutrient solution that would be neutral (result in no substrate-pH change) for each species.
This neutral percent NH4+-N of total N ranged from approximately 0% for geranium to 35% for pentas (Pentas lanceolata Forssk.). Evaluating the tendency to raise or lower substrate-pH across a range of floriculture species could help predict NH4+:NO3– ratios for a neutral pH effect and assist growers in managing substrate-pH for container production.
The objective was to quantify effects of floriculture plant species on substrate-pH. In a growth chamber factorial experiment, 15 floriculture species were grown in 70%:30% by volume peat:perlite substrate and fertilized with nutrient solutions containing 100 mg L‑1 N at NH4+-N:NO3–-N nitrogen ratios of 0:100, 20:80, or 40:60. After 33 days, species and solution type effects on substrate-pH and estimated mEq of acid or base produced were evaluated.
Final substrate-pH ranged from 4.83 for geranium (Pelargonium × hortorum Bailey L.H.) in 40:60 solution to 6.58 for lisianthus in 0:100 solution, compared to an initial substrate-pH of 5.84. This change in substrate-pH corresponded with a net mEq of acid or base produced g‑1 tissue dry mass gain (NMEQ) ranging across solutions and species from 1.47 of base for lisianthus (Eustoma grandiflorum Salisb.) in the 0:100 solution to 2.10 of acid for coleus (Solenostemon scutellariodes L.) in the 40:60 solution.
With the 0:100 solution, species that took up more anions than cations into plant tissue tended to have a more basic effect on substrate-pH, as would be expected to maintain electroneutrality.
Data were used to estimate the percent NH4+-N of total N in a nutrient solution that would be neutral (result in no substrate-pH change) for each species.
This neutral percent NH4+-N of total N ranged from approximately 0% for geranium to 35% for pentas (Pentas lanceolata Forssk.). Evaluating the tendency to raise or lower substrate-pH across a range of floriculture species could help predict NH4+:NO3– ratios for a neutral pH effect and assist growers in managing substrate-pH for container production.
Publication
Authors
R.W. Dickson, P.R. Fisher
Keywords
soilless substrate, iron efficiency, pH management, acidity, basicity
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