An Evaluation of Plant Growth and Development under Various Daily Quantum Integrals
| Autor: | R.A. Norton, Ian J. Warrington |
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| Rok vydání: | 1991 |
| Předmět: | |
| Zdroj: | Journal of the American Society for Horticultural Science. 116:544-551 |
| ISSN: | 2327-9788 0003-1062 |
| DOI: | 10.21273/jashs.116.3.544 |
| Popis: | Plants of chrysanthemum (Dendranthema × grandiflorum (Ramat.) Kitamura), radish (Raphanus sativus L.), corn (Zea mays L.), and cucumber (Cucumis sativus L.) were grown under 8-, 12-, 18- or 24-hour daylengths and at three photosynthetic photon fluxes (PPF) within each daylength to evaluate growth and development responses to daily quantum integral (PPF x duration). For the same daily quantum integral, dry matter accumulation and leaf area development were less under 24-hour than under 18-hour daylengths with chrysanthemum and radish. With corn and cucumber, these values were similar under 12-, 18-, and 24-hour daylengths. In all of the species, leaf area and dry matter development were lowest under the 8-hour daylength. Continuous (24-hour) daylength produced some growth abnormalities in radish and chrysanthemum. Specific leaf weight in all species and flower node count in cucumber were linearly related to daily quantum integral up to the highest values examined (73.5 mol·day -l ·m -2 ). All species showed expected photoperiod responses with respect to flowering, but the rate of floral development and number of flower buds formed were highest under the highest PPF (and highest daily quantum integral) treatments. The results indicate that field phenotypes can be obtained in controlled environment (CE) conditions, providing the field daylength and daily quantum integral conditions are reproduced. Developments in lighting technology have resulted in a shift away from the use of fluorescent tubes in CE lighting systems to the use of high intensity discharge lamps. Combinations of high intensity discharge and incandescent lamps can give good light distributions with fewer lamps, acceptable spectral quality, and, if needed, PPFs equivalent to peak natural daylight values (Bugbee and Salisbury, 1988; Warrington et al., 1978a, 1978b). The ability to achieve high PPFs raises important questions with respect to the choice and management of lighting systems for CE experiments. Previously, Warrington et al. (1978b) showed that PPF operating levels of 650 to 750 µmol·s -1 |
| Databáze: | OpenAIRE |
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