ISHS Acta Horticulturae 515: XXV International Horticultural Congress, Part 5: Culture Techniques with Special Emphasis on Environmental Implications Chemical, Physical and Biological Means of Regulating Crop Growth in Ornamentals and Other Crops
IMPROVEMENT OF PLANT QUALITY BY INTEGRATED CONTROL OF LIGHT, TEMPERATURE AND DIF-STRATEGY |
| Author: | J.V.M. Vogelezang |
| Keywords: | Fuchsia x hybrida, bedding plants, crop quality, DIF, elongation growth, light, Pelargonium zonale, Salvia splendens, temperature, Verbena hybrid |
| Abstract:
Growers still require chemical growth retardants in order to obtain acceptable plant height. For some time it is known that elongation growth can be controlled more ‘naturally’ using DIF (difference between day and night temperature). Effectiveness of DIF was studied in relation to light and temperature level as well as the response of different plant parts to DIF on a range of bedding plants. Research was carried out in 16 climatized daylight chambers with Fuchsia x hybrida, Salvia splendens, Pelargonium zonale and Verbena hybrid. The experimental design was factorial with two light levels (resulting in 1.6 and 3.8 mol.m-2.day-1), two levels of air temperature (17 and 20EC) and two DIF-strategies (+2 and -6EC). Negative DIF reduced plant height, varying from 25 (Pelargonium) to 35% (others) compared to DIF+2. Length of leaf petioles and - surface were reduced to a lesser extent (10 to 15%) than length of the main shoot by negative DIF. No interaction was found between DIF-strategy and light or temperature level on elongation growth in the investigated range. Plant quality was highly affected. A high light level increased plant weight per cm (‘density’), leaf thickness and chlorophyll content. A high level of temperature favoured side shoot formation and/or flowering when combined with a high light level. Compared to traditional growing circumstances plant quality improved substantially by combining negative DIF with a higher 24-hour mean temperature than usual. In this case positive effects of negative DIF (compactness, plant density, leaf thickness) are completed with positive effects of a higher 24-hour mean temperature (cultivation time, crop weight). | |
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