SUPPLEMENTAL LIGHTING for GREENHOUSE CROPS Ir. J.J. Spaargaren along with Hortilux Schreder B.V. and P.L. Light Systems, Inc. i © August, 2001, Hortilux Schréder B.V. and P.L. Light Systems, Inc. All rights reserved. 1st edition: November, 2000, Dutch version. 2nd edition: August, 2001, English revised version. This book is created using Adobe Pagemaker 6.5 on a Power Mac G4. The Helvetica font is used for the text. No parts of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from Hortilux Schréder B.V. and P.L. Light Systems, Inc. Ordering: This book can be ordered at 45 euro, 100 Can.$ or 65 US$ incl.VAT, in Europe, Asia, Africa, Australia and New Zealand from Hortilux Schréder B.V., Groote Noort 11, NL 2681 DJ Monster, The Netherlands. Phone + 31 (0)174 28 66 28, Telefax + 31 (0)174 28 66 48. Web site: http://www.hortilux.com E-mail: [email protected] in Canada, North and South America, from P.L. Light Systems, Inc., 4800 Hinan Drive, R.R.#1, Beamsville, Ontario, Canada LOR 1B1. Phone + 1 905 563 41 33, Telefax + 1 905 563 04 45, Toll Free + (800) 263 02 13. Web site: http://www.pllight.com, E-mail: [email protected] Liability Every effort has been made to ensure that the information in this book is accurate. However, Hortilux Schréder B.V., P.L. Light Systems, Inc. and Ir. J.J. Spaargaren are not responisble for following advices made in this book. ii FOREWORD Since the previous edition of this book (Application Contents of growlight in greenhouses, 1985), several advances The book starts with a Summary and a table pre- have been made in the field of supplemental lighting senting a brief overview of the production methods used for supplemental lighting of various greenhouse of greenhouse crops. crops in The Netherlands. On page 6 is explained how to adjust minimum light levels of supplemental The design of supplemental lighting installations can lighting to the natural light sums in other countries. be optimized using sophisticated computer models. Using supplemental lighting is more than installing New luminaires are available with ever increasing luminaires. Supplemental lighting interacts with many efficacies (efficiency of converting electric energy into other production aspects and, thus, with the overall management of a greenhouse operation. It is impor- useful light – usually expressed in lumen per watt). tant that a grower uses the correct lighting strate- High-Pressure Sodium (HPS) lamps are widely used gies. Hortilux Schréder B.V. and P.L. Light Systems, Inc. for their highest conversion efficiency (approximately have several tools to provide recommendations 30%). Further increases in conversion efficiencies (Chapters 1 and 2). are expected. Hortilux Schréder B.V. and P.L. Light Sys- Subsequent chapters describe the physics and plant tems, Inc. are continuing to contribute towards this goal. physiology behind supplemental lighting. Chapter 3 describes the basic physical principles of light as elec- tromagnetic radiation. The effects of the light spec- Research in plant physiology uncovered many crop trum on plant growth and development are summa- responses to supplemental lighting. It is becoming rized in figure 3.29. clear that not only light intensity should be taken into Chapter 4 discusses some of the plant physiology consideration but also light sum, lighting period, and behind growth and development. corresponding daylength. Particularly the daylength Chapter 5 focuses on the units of light an their con- may have a significant impact on growth and devel- versions. In Chapter 6, recommendations for supplemental opment, as will be discussed in this book. Integrated lighting strategies are presented. These recommen- light sums are now used to indicate threshold values dations include light intensity, light sum, daylength, below which problems can occur with flower initia- etc. The light intensity provided by the installed tion, development, growth rate, and branching. supplemental lighting system can be compared with the desired light levels for e.g. foliage plants, flower- The basis for plant growth is the increase in dry mat- ing pot plants, and cut flowers. The information pro- vided for pot plants also discusses minimum light ter. The building blocks for dry matter increase are levels for the end user (inside the consumer’s living supplied by photosynthesis. In addition to light, car- room) because this information is important for main- bon dioxide, and water, chlorophyll content and the taining satisfactory plant quality. For cut flowers, appropriate temperature determine the rate of pho- threshold values are presented below which plant tosynthesis. The optimum rate of photosynthesis is quality problems can be expected. only attainable when none of these growth factors At the end of Chapter 6, supplemental lighting rec- ommendations for greenhouse vegetable production are limiting. For example, a high root temperature are presented. during rose production considerably increases the Chapters 7 through 11 discuss the technical as- consumption of sugars through respiration. As a re- pects of supplemental lighting installations. sult, the net rate of whole-plant photosynthesis may Chapter 7 discusses the various light sources. decline even to the point of an overall loss of biom- Chapter 8 describes the construction of luminaires, ass despite the use of supplemental lighting to in- in 8a for Europe and in 8b for North America, and Chapter 9 presents the luminaires produced by crease plant growth rates. Hortilux Schréder B.V. (in 9a) and P.L. Light Systems, Inc. (in 9b). Plant nutrition also has a major impact on plant Chapter 10 discusses the process by which Hortilux growth. Without proper nutrition, the necessary build- Schréder B.V. and P.L. Light Systems, Inc. design and ing blocks, such as enzymes, will not be available. quote supplemental lighting installations. Therefore, plant nutritional aspects will also be ad- Chapter 11 describes the electrical installation. Finally, a Reference list and an Index are included dressed in this book. to help a reader find information quickly. iii Acknowledgements The first edition, published in Dutch in November * The following publishers kindly permitted to reprint figures from 2000, was written in co-operation with the technical their publications. staff of Hortilux Schréder B.V., and Dr. Tjeerd Agricultural Institute of Canada, figure 6.15, from Demers et al.,1991, Blacquière from the Research Station for Floricul- in Canadian Journal of Plant Science. American Society for Horticultural Science, figure 4.13, from Heins et ture and Glasshouse Vegetables in Aalsmeer, The al., 1986, in the Journal of American Society of Horticultural Science, Netherlands. figure 6.13 from Blain et al., 1987, in HortScience, figures 6.17 and I am especially indebted to Tjeerd who gave me valu- 6.19 from Boivin et al., 1987, in HortScience. able stimulating advice. He thoroughly reviewed the American Society of Plant Biologists (formerly American Society of Plant Physiologists), figure 3.16, from Zscheille et al, 1942 in Plant first six chapters. Physiology. Elsevier Publishers, figures 6.14 and 6.16, from Van Uffelen and This second edition of the book in English would Heuvelink, in Groenten en Fruit. not have been accomplished without the excellent Elsevier Science, figure 6.3, from Bruggink, 1987, in Scientia Horticulturae, figures 3.21 and 3.22, from McCree, 1972, in Agricul- translation work, improvements and additions for the tural Meteorology. world market of: Harvard College Library, figure 3.15, from Zscheile and Comar, 1941, in Botanical Gazette. - Dr. Theo J. Blom, Greenhouse Floriculture, De- Headley Brothers/The Invicta Press, figures 6.18, 6.20, 6.21, 6.22,6.23, 6.26, 6.27, from McAvoy, Janes (1991) and Cockshull et al. , 1992 and partment of Plant Agriculture, University of Guelph, 1995, in The Journal of Horticultural Science and Biotechnology. Vineland Station, Ontario, Canada, International Society for Horticultural Science (ISHS), figure 4.10, - Dr. Arend-Jan Both, Assistant Extension Special- from Morisot, 1996, figure 4.14, from Faust and Heins, 1997, figure ist, Rutgers, The State University of New Jersey, 3.18, from Schurer in Acta Horticulturae. Kluwer Academic Publishers, figure 3.14, from H. Smith, 1986, in: Bioresource Engineering, Department of Plant R.E.Kendrick and G.H.M. Kronenberg (eds.), Photomorphogenesis in Science, U.S.A., Plants, Martinus Nijhoff Publishers, Dordrecht. - Drs. Willem van Winden, Research Station for Flo- McGraw-Hill, Publishers, figure 4.5, from Leopold and Kriedemann, riculture and Glasshouse Vegetables in Naaldwijk, 1975, in Plant Growth and Development. Munksgaard, International Publishers, Ltd., figure 4.8, from Björkman The Netherlands. and Holmgren, 1963, in Physiologia Plantarum. The Optical Society of America, figure 4.16, from Gates et al., 1965, in Special thanks go to Arend-Jan and Theo with whom Applied Optics. I have exchanged countless e-mails. Oxford University Press, figure 6.12, from D.W. Hand et al., 1992. J. Finally, I want to thank publishers*, researchers and Exp.Botany, Vol. 43, No.248. Sinauer Associates, Inc., Publishers, figure 3.24, from Vierstra and companies for the use of information and graphics. Quail, 1983, in Taiz and Zeiger, 1998, Plant Physiology. Dr. T.C. Vogelmann, University of Wyoming, figure 3.19. Ir. Jaap Spaargaren, Aalsmeer,