THE EFFECT OF IRRIGATION WATER TEMPERATURE ON THE GERMINATION AND GROWTH OF PLANTS

Seeds of 5 different plant species growing in punnets were irrigated with water at different temperatures (5°, 10°, 15°, 20°, 25°, 30°C (or 5°, 15°, and 30°C). The day/night temperature regime was 25°/17°C or 25°/20°C. Maximum depression of substrate and leaf temperature caused by the irrigation water temperature (IWT) was about 13°C. The substrate temperature returned to air temperature within 40 minutes and the leaves of the plants within 0.5°C of the air temperature in a maximum time of 5 minutes.
The germination and growth of everlasting daisy (Acrotinium sp.) was not affected by IWT at 5° and 15°C. Cold IWT reduced the percentage and speed of germination and internode length of beans (Phaseolus vulgaris – Redlands Wonder) but did not affect dry weight or leaf area.
IWT at 5°C also caused distortion to the leaves.
Dry weight and leaf area of the cabbage (Grey green hybrid) was not affected by IWT but watering at 10°, 15° and 20°C stimulated the rate of germination.
Percentage germination was not affected.
The length of the longest leaf was also reduced by cold (5° to 20°C) water.
The dry weight leaf area and length of longest leaf of Winterlake lettuce was decreased as IWT fell.
However IWT at 15°C compared to that of 5°C and 25°C stimulated the leaf area and dry weight of Great lakes lettuce.
The dry weight leaf area and internode length and rate of germination (but not %) of tomatoes (Grosse Lisse) was reduced by cold water (up to a 33% reduction compared to water at 25°C). IWT at 30°C reduced the internode length and rate of germination compared to that at 25°C.

Symposium on Propagation and Raising of Nursery Stock

R.J. Worrall

https://doi.org/10.17660/ActaHortic.1978.79.16