Articles
PLANT BIOASSAY FOR SUBSTRATES
Article number
644_28
Pages
211 – 215
Language
English
Abstract
Peat is the most commonly used constituent in substrates especially for young flower and vegetable plants and ornamental pot plants.
Wide knowledge of chemical and physical aspects of peat is a good basis of successful and safe use of peat-based substrates by professional growers.
Although standard chemical and physical measurements show normal values, growth disturbances may occur in peat.
It is often difficult to find out the chemical compounds that cause the problem.
The aim of this study was to develop a good test method to screen substrates and their raw materials.
The tests were conducted on the growth of Chinese cabbage, cucumber and leaf lettuce seedlings in different materials (e.g. peat, soil, compost mixture). The test plants were monitored both visually and by measurements for germination, seedling emergence and development, and root condition.
The results were compared with those of the control substrate.
So far, we have tested 156 peat substrates.
Of these, 31% of the samples were peat products and 69% were raw materials taken from different peat moss production areas in Finland.
The fresh yields of Chinese cabbage, cucumber and lettuce were similar but lettuce and Chinese cabbage are more responsive to poor-quality peat.
The proportion of poor-quality peat samples was about 14% and most of these samples were known or suspected of having some association with growth problems like self-heating or too high nitrogen levels.
We could not find any statistical correlation between the bioassay and chemical assay results and it seems that poor-quality peats could not be identified by chemical or physical analyses only.
Our bioassay is suitable for routine testing because it recognizes the peats which have growth inhibiting properties, but to find out the reasons for inhibiting growth we need more microbiological and chemical research.
Wide knowledge of chemical and physical aspects of peat is a good basis of successful and safe use of peat-based substrates by professional growers.
Although standard chemical and physical measurements show normal values, growth disturbances may occur in peat.
It is often difficult to find out the chemical compounds that cause the problem.
The aim of this study was to develop a good test method to screen substrates and their raw materials.
The tests were conducted on the growth of Chinese cabbage, cucumber and leaf lettuce seedlings in different materials (e.g. peat, soil, compost mixture). The test plants were monitored both visually and by measurements for germination, seedling emergence and development, and root condition.
The results were compared with those of the control substrate.
So far, we have tested 156 peat substrates.
Of these, 31% of the samples were peat products and 69% were raw materials taken from different peat moss production areas in Finland.
The fresh yields of Chinese cabbage, cucumber and lettuce were similar but lettuce and Chinese cabbage are more responsive to poor-quality peat.
The proportion of poor-quality peat samples was about 14% and most of these samples were known or suspected of having some association with growth problems like self-heating or too high nitrogen levels.
We could not find any statistical correlation between the bioassay and chemical assay results and it seems that poor-quality peats could not be identified by chemical or physical analyses only.
Our bioassay is suitable for routine testing because it recognizes the peats which have growth inhibiting properties, but to find out the reasons for inhibiting growth we need more microbiological and chemical research.
Authors
R. Kemppainen, H. Avikainen, M. Herranen, O. Reinikainen, R. Tahvonen
Keywords
chinese cabbage, cucumber, growth problems, lettuce, peat
Online Articles (81)