Growth of Bedding Plants in Response to Root-zone Heating and Night Temperature Regimes

Abstract

Nine bedding plant vegetable and flower cultivars were grown in each of 10 night air and root media temperature regimes. Generally, fresh and dry weights were greater at 16°C than at 7° night air temperature when root-zone (RZ) heating was not used. Soil warming increased fresh and dry weights of all cultivars grown at 16° night air temperatures. When air temperatures were below 16°, soil warming maintained fresh and dry weights equivalent to or better than plants grown at 16° without soil warming. Two split-night (SN) air temperature regimes were as effective as a constant 16° night temperature, ranking first and 3rd in fresh and dry weight per unit of energy consumption. All soil warming treatments had higher energy productivity than the 16° air temperature treatment with no RZ heating.

Mineral Nutrition of Tomato under Diurnal Temperature Variation of Root and Shoot

“…The diurnal variation of air and soil temperature may tables benefitted from constant root-zone heating when air was cool at night (Shedlosky and White, 1987). The play a role in nitrogen nutrition of field crops.…”

“…Tomato seedlings grew more slowly under +14°C than +5°C air DIF, except when the root‐zone was heated constantly. Various species of flowers and vegetables benefitted from constant root‐zone heating when air was cool at night (Shedlosky and White, 1987) The seedlings grew at similar rates under 7°C or 16°C air temperature at night, when the roots were heated constantly to 16°C. Leaf area expansion of potato ( Solanum tuberosum L.) had an optimum DIF that increased with day temperature, from a DIF of 0°C with days at 20°C, to a DIF of +11°C with days at 35°C (Benoit et al, 1986) The +14°C air DIF in our study may be deleterious because it was combined with a relatively cool mean temperature.…”

“…if the air is cool at night (Gosselin and Trudel, 1983a;Shedlosky and White, 1987). Heating the root zone to Plant Material 24ЊC increases phosphorus and potassium concentra-…”

“…A root‐zone temperature cooler than 15°C dramatically slows the uptake of mineral elements in the shoot of tomato, even if the shoot is warm (Cannell et al, 1963; Cornillon, 1974), and it has an equally dramatic effect on growth (Martin and Wilcox, 1963) Constantly heating roots to 16 to 18°C increases shoot dry weight if the air is cool at night (Gosselin and Trudel, 1983a; Shedlosky and White, 1987). Heating the root zone to 24°C increases phosphorus and potassium concentrations in the shoot of tomato grown under a 12 or 15°C night temperature, but the effect of heating roots is much less at air temperatures of 21°C or above (Gosselin and Trudel, 1983b) Under controlled conditions with a forced transition in air and root temperature from night to day, roots that are cool only in the night inhibit shoot growth far less than roots that are cool constantly or only in the day (Harssema, 1977; Ali et al, 1994).…”

Crop Productivity and Morphology of Petunia and Geranium in Response to Low Night Temperature

“…A linear relationship between 0 and moisture tension was found between 0 and 2 kPa, whereas a quadratic relationship existed from 2 to 10 kPa. Several researchers developed a cubic regres- sion model to describe the moisture retention curve, with the goal of predicting the container-specific values of air space and container capacity (8,10,16).…”