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Plant Growth Under Controlled Conditions. V. The Relation between Age, Light, Variety and Thermoperiodicity of Tomatoes

F. W. Went
American Journal of Botany
Vol. 32, No. 8 (Oct., 1945), pp. 469-479
Stable URL: http://www.jstor.org/stable/2437574
Page Count: 11
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Plant Growth Under Controlled Conditions. V. The Relation between Age, Light, Variety and Thermoperiodicity of Tomatoes
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Abstract

The thermoperiodicity of tomato plants was studied in detail, considering interrelations between age of plant, light intensity and variety on the one hand, and stem elongation at six night and two day temperatures on the other hand. It was found that a gradual shift of the optimal night temperature occurred, from 30⚬C. in small plants to 18⚬C. for the San Jose Canner and 13⚬C. for the Illinois T19 in the early fruiting stage. A similar response was found in 14 other tomato varieties, but they each had slightly different temperature characteristics. In general the English and Greenhouse varieties grew fastest and had the lowest optimal night temperatures. Western varieties had the highest optimal night temperatures, and Eastern varieties were intermediate between the other two as far as night temperature was concerned, but had the lowest absolute growth rates. When the tomato plants were grown in full sunlight, their optimal night temperature was higher than on cloudy days, provided they were shaded by other plants. In artificial light the optimal night temperature fell off very rapidly with decreasing total illumination. Incidence of virus diseases was greatly modified by both day and night temperature. In the discussion it is pointed out that these complex interrelationships are examples of a multidimensional causality, which can be presented properly only in multidimensional models.

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