The Influence of Temperature on the Growth and Flowering of Oriental Lilies
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Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author. THE INFLUENCE OF TEMPERATURE ON THE GROWTH AND FLOWERING OF ORIENTAL LILIES (Lilium cultivars) A thesis presented in partial fu lfilment of the requirements for the degree of Doctor of Philosophy at Massey University. John Paiba Salinger 1978 ABSTRACT The potentiality of growi ng dwarf cu ltivars of Orienta l lilies as f lmve ring pot plants wa s investigated. Two cu ltivars, 1 L. auratwn 'Little Gem and L xparkmanni 'Li ttle Robin' were grown to assess their su itability and determi ne a predictable schedule of production. Initially it was established that these plants could be grown sa tisfact ori ly in containers and that after adequate vernalization adequate growth and flowering took place. In bu lbs selected after na tura l senescence, ve rna lization can be achieved by planting and sto ring the bulbs outdoors to exp erience natural wi nter chi lling and also artificia lly by storage at controlled cool temperatures. Planting prior to art ificial cool storage wa s not advantageous. There is a minimum period of storage of 35 days and preferably 42 days for both cu ltiva rs, wh ile temperatures ma y ra nge ° ° ° from 1. 7 C to 8 C for L. auratum 'Li ttle Gem and to 12 C for L. x parkmanni 'Litt le Rob in'. The periods from planting to emergence and emergence to macroscopically visib le flower buds are inversely related to the length of time the bulbs are st ored, irrespective of the cool temperature. Subsequent growth to anthesis is directly related to the temp erature at which the plant s are grown and independant of previous storage times and temperatures. The time required to achieve anthesis is consi stent in any one temperature re gime. Although the longer the time the bulbs experience cool temperatu res, the sooner the plants achieve anthesis, the tota l time from commencement of st orage to anthesis is simi lar for all storage periods up to 10 weeks. When bulbs are inadequately vernalized , gro wth and floweri ng is irregular; growth being rosetted and anthesis delayed or occuring spasmodica lly. The growth and development of lilies is considered and compared with that of other bulbous geophyles. ACKNOWLEDGEMENTS Gratefu l thanks are given to Prof. J.A. Veale and Prof. R. G. Thomas for discussions and provision of facilities. Thanks are acknowledged to Prof. R. J. Townsley, Dr I. Gord on and Dr M.A. Nichols for sta tistica l assistance and to Dr J.S. Yeates for the donation of bulbs. The assistance of technical sta ff of Ma ssey University and the encouragement of my own family in the cu ltiva tion of the plants is gratefully acknowledged. TA BLE OF CONTENTS Chap ter Page Ab stract Acknowledgements Introduction l The lily plant 3 1.1 Classification of lilies 3 1.1. 1 Botanical classification 3 1.1. 2 Horticul tural clas sific ation 4 l.l. 3 Comparison of Longiflorum hybrid s and Or iental hybrids 2 Gr owth and development of the lily plan t 6 2. l Studies on development 6 2.2 Lily mo rphology 7 2.2. l Basal or con t ractile root 8 2.2.2 Stem roots 10 2.2.3 The stem ll 2.2.4 The flmver 15 2.2.5 The nectaries or osmophores 16 2.2. 6 Fruit and seed 17 3 Factor s in fluencing the flowering of lilies 18 3. l Inductive factors 3.2 Vernalization 1 9 3.3 Dormancy in lilies 2l 3.4 For cing of lilies 21 3.4 .l The producti on stage 23 3.4.2 The programming stage 23 3.4.3 The gr eenhouse stage 23 3.5 The influence of temp er atur e on reproduction of lil ies 24 3. 5. 1 Germina tion of seed 24 Chapter Pag e 3.5.2 Epigeal ger minat ion 25 3.5.3 Temperature and fertilizat ion 25 3.6 Reproduction asexual ly 27 3.7 The influence of light on flower ing in lilies 27 3.7. l Light intensity 27 3.7.2 Light as a subst itution for vernalizat ion 28 3.7 .3 Photoperiod 29 4 The geophyt ic hab it 30 4. 1 Geophytes 30 4. 2 Comparison of geophytes 31 4.3 Def inition of bu lbous geophy tes 34 4.4 Compar ison of lilies wi th other types of bu lbs 35 4. 4. 1 Periodic classificat ion 35 4.4.2 Structural classification 36 4.4.3 Thermo-r esponsive classificat ion 38 4.4.4 Structural comparison between lilies and other monocots 39 5 Exper iment al aspect s Exper iment 1 5. 1 Ob ject 5. 1. 2 Materials and met hod s r�2 5.1. 3 Record s and Result s 44 5. 1.4 Discussion 47 5. 1.5 Conclusions 49 Exper iment II 5.2 Ob ject 49 5. 2. l Mat er ials and me thod s 49 5. 2.3 Records and Resu lts 51 5.2.4 Discussion 54 5.2.5 Cone lu sions 55 Chapter Page Exp eriment Ill 5.3.1 Ob ject 55 5.3.2 Materials and methods 56 5.3.3 Records and Results 58 5. 3.4 Discussion 63 5.3.5 Conclusions 65 Exp eriment IV 5.4.1 Object 65 5.4.2 Materials and methods 65 5.4.3 Records and Results 66 5. 4. 4 Discussion 68 5.4.5 Conclusions 69 Experiment V 5.5. 1 Object 70 5. 5.2 Haterials and method s 70 5.5.3 Records and R e sul t s 7l 5. 5.4 Discussion 77 5.5.5 Conclusi on 78 Experiment VI 5.6.1 Ob ject 79 5.6.2 Mat erials and me t hod s 79 5.6.3 Records and Results 80 5.6.4 Discussion 83 5.6.5 Conclusions 84 6 Discussion and cone lu sions 6.1 Introduction 85 6.2 Cool temperature effe c t s 85 6. 2. l Grmvth to anthesis 85 6.3 Cultivation pe riods 86 6.3.1 Total cu ltivat ion period 86 6.3.2 Cu ltiva tion aft er storage 86 6.4 Blueprint grmving 87 6.5 Fut ure research 88 6. 5. 1 Long term cool storage 88- 6.5.2 Bu lb production 88 Chapter Page 6.5.3 Genetic aspects 89 Graphs of experiment s 90 Appendices 96 Bibliography 118 LIST OF ILLUSTRATIONS Princ ipa l parts of a lily Between pages 6-7 Photograph 1 Longtitudinal section of bulbs 13-14 2 Foliage of L x parkma nni 'Li ttle Robin' 13-14 3 View of Experiment 2 54-55 4 Flower of L. auraturn 'Little Gem' 54-55 5 Exper iment 5: inf luence of preplanting storage 78-79 6 Experiment 6: plants in gro\vth cabinets 84-85 7 Exp eriment 6: plants in glasshouse 84-85 l. INTRODUCTION Plants of the genus Lilium have for centuries had a particular significance for people, either as a source of food (Wilson 1929) , the bulbs being ga t hered from the wild and eaten in Japan or with religious connotations in Chris tian communit ies (Woodcock and Stearn 1950). In addit ion they have been admir ed and cultiva ted as plants of beauty to decorate ga rdens. The alimentary aspect will not be considered further, while the religious significance must be referred to in greater detail. Traditionally the pure white flowers of Li lium candi dum ha ve been associated >vith the �1adonna, in fact both the specific and common English name indicate that the flowers were of exc ep tional purit y. Similarly L. longiflor>um has been known for :·ears as Easter lily and many mill ions of bulbs are fo rced in the Unit ed States of America as a flowering pot plant specifically for sale at that time and at no other period of the year. In New Zealand, lilies with whit e flowers either L. r>egale or L. longiflor>um 1 Dutch Gl ory 1 , are grmvn outdoors to be sold as cut flowers at Chris tmas only; should they flower too early or too late they have no commercial value. Those spec ies and cultiva rs with coloured flowers, particularly L. (Asiatic hy brid) 1 Enchantment' and culti vars of L. speciosum are grown for cut flower sale in Eu rope and mo re recent ly, L. X par>kmanni cultivars bred in New Zealand have been exported for the same purpose (Do reen pers. cornrn.). Ap art from Eas ter lily cul tiva rs, few other s are grown as pot plants for they do no t possess the des irable characteristics of a pot plant as specified by Sa chs et al. (1976), mostly being too tall or not attaining the desirable height/wid th ratio of 1.62/l. In fact growth retardants such as ch�rmequat, ethepho n or ancymidol are applied to 2. Easter and Asiatic hyb rid lilies (Dick 1974, Wad e 1972, Roh and Wilkins 1977b) to obtain a mo re compact and suitab ly shaped plant. Woodley and Tho mas (1973) similarly ap plied growth retardants to L.