Leaf-Fruit Relationship in Kiwifruit (Actinidia Deliciosa (A. Chev.) C.F. Liang Et A.R. Ferguson)
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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. LEAF-FRUIT RELATIONSHIP IN KIYIFRUIT (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson) A thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plan t Phy iology s at Massey University, Palmers ton North New Zealand Robert Lai 1987 TABLE OF CONTENTS Page Abs tract . vii Acknowledgements x List of Tables . xi List of Figures . xv List of Plates . xx GENERAL INTRODUCTION . 1 1. GENERAL MATERIALS AND METHODS. 4 1.1 Plan t Ma terial 4 1.2 Plant Growth Envi ronment and Cultural Conditions . 6 1.3 Collection of Leaf Data . 8 1.4 Collect ion of Fruit Data. 11 4 1.5 1 C Me thod ... 13 1.6 Data Analysis 20 2. KIWIFRUIT LEAF PHYSIOLOGY . 21 2.1 Introduction. 21 2.2 Experiment 2A 27 2.2.1 Introduction 27 2.2.2 Materials and Methods . 27 2.2.3 Results. 28 2.3 Experiment 2B . 33 2.3.1 Introduction 33 2.3.2 Materials and Methods . 34 2.3.3 Results. 37 2.4 Experiment 2C . 53 2.4.1 Introduction 53 2.4.2 Materials and Methods . 53 2.4.3 Results ....... 54 ii Page 2.5 Discussion . 56 2.5.1 Kiwifruit Leaf Growth. 56 2.5.2 Light Responses and Shade Effects. 58 2.5.3 Temperature Responses . 60 2.5.4 Light and Temperature Interactions 62 2.5.5 Acclimation to Temperature . 64 2.5.6 Male and Female Photosyn thesis . 66 2.5.7 Effect of Frui t Sinks on Leaf Photosynthesis 67 3. FRUIT DEVELOPMENT . 69 3.1 Introduction. 69 3.2 Experimen t 3A 73 3.2.1 Introduction 73 3.2.2 Materials and Methods . 73 3.3 Results 76 3.4 Discussion . 84 3 ... 1 Kiwifruit Growth Pattern 84 3.4.2 Fruit Growth Stages . 86 3.4.3 Frui t Dry \Jeight . 86 4. FACTORS AFFECTING FRUIT SINK STRENGTH . 88 4.1 Introduction. 88 4.2 Experimen t 4A 94 4.2.1 Introduction . 94 4.2.2 Materials and Methods. 95 4.2.3 Results. 99 4.3 Experiment 4B 109 4.3.1 Introduction 109 4.3.2 Materials and Methods . 109 4.3.3 Results. 112 4.4 Experiment 4C 123 4.4.1 Introduction 123 4.4.2 Materials and Methods . 123 4.4-: 3 Results. 125 iii Page 4.5 Discussion ......... 131 4.5.1 Interfruit Competit ion 131 4.5.2 Long and Short Shoots. 133 4.5.3 Fruit Pedicel Diameter 136 4.5.4 Effect of Time of Flower Anthesis. 136 5. ASSIMILATE SUPPLY FROM SOURCE LEAVES ON A FRUITING SHOOT 141 5.1 Introduction . 141 5.2 Experiment 5A 147 5.2.1 Introduction 147 5.2.2 Materials and Methods . 147 5.2.3 Results. 148 5.3 Experiment 5B . .. 150 5.3.1 Introduction . 150 5.3.2 Materials and Methods . 151 5.3.3 Resul ts. 151 5.4 Experiment 5C . 153 5.4.1 Introduction 153 5.4.2 Materials and Methods. 154 5.4.3 Results. 157 5.5 Discussion . 163 5.5.1 The Source Leaf. 163 5.5.2 Direction of Assimilate Translocation. 164 5.5.3 Sectorised Transport in the Fruit ing Lateral 165 5.5.4 Effects of Pruning on Assimilate Distribution. 166 6. SOURCES OF ASSIMILATE SUPPLY OUTSIDE THE FRUITING SHOOT . 168 6.1 Introduction. 168 6.2 Experiment 6A 171 6.2.1 Introduction 171 6.2.2 Materials and Methods . 171 6.2.3 Results. 174 6.3 Experimen t 6B ; . ' . ' 182 6.3.1 Introduction . 182 6.3.2 Materials and Methods. 183 6.3.3 Results ....... 189 iv Page 6.4 Experiment 6C .. .. .. 194 6.4.1 Introduction .... 194 6.4.2 Materials and Methods. 194 6.4.3 Results. 195 6.5 Discussion ... 200 6.5.1 Effect of Vege tative Shoots. 200 6.5.2 Leaf-Fruit Ratios .. 201 6.5.3 Effect of Sink Strength on Assimilate Translocation. 203 6.5.4 Dependence on Curren t Photosynthesis . 204 7. LEAF EFFECTS ON FRUIT GROWTH 205 7.1 Introduction . 205 7.2 Experimen t 7A . 208 7.2.1 Introduction 208 7.2.2 Materials and Methods . 209 7.2.3 Results. 214 7.3 Experimen t 7B . 239 7.3.1 Introduction 239 7.3.2 Materials and Methods . 239 7.3.3 Results. 240 7.4 Discussion . 244 7.4.1 Vine Performance 244 7.4.2 Leaf Inhibitory Effect 246 7.4.3 Time of Pruning .... 249 7.4.4 Effect of Shoot Regrowth 250 7.4.5 Shoot Fruit Numbers and Fruit Size 251 8. LEAF-FRUIT RATIO AND FRUIT GROWTH . 253 8.1 Introduction. 253 8.2 Experiment 8A 255 8.2.1 Introduction 255 8.2.2 Materials and Methods . 255 8.2.3 Results ....... 256 v Page 8.3 Experiment 8B ....... 268 8.3.1 Int roduction .... 268 8.3.2 Materials and Methods . 268 8.3.3 Results. 269 8.4 Discussion ... 274 8.4.1 Effect of Girdling 274 8.4.2 Leaf-Fruit Ratios .. 276 8.4.3 Interfrui t Competition 278 9. GENERAL DISCUSSION ............. 280 9.1 Canopy Establishmen t and Photosynthesis 280 9.2 Shade and Temperature Effects on Pho tosynthesis . 282 9.3 Effects of the Presence of Frui ts on Photosynthesis 283 9.4 Sources of Assimilate Supply to Fruits . 284 9.S Flexibili ty in Assimilate Translocation . 286 9.6 Fruit Development and Seed Number ..... 287 9.7 Effects of Pre-An thesis Factors on Fruit Size 288 9.8 Leaf-Fruit Ra tios .......... 290 9.9 Leaf Inhibitory Effects on Fruit Growth 292 9.10 Interfruit Competition. 293 CONCLUSION . 296 BIBLIOGRAPHY 299 vi ABSTRACT Net photosynthe tic rates of kiwi fruit (Actinidia deliciosa (A. Chev. ) C.F. Liang et A.R. Ferguson) leaves were lowered by as much as 50 % of ligh t saturated rates when the vines were shaded to half the ligh t satura ting level (280 uE m-2 S-1). The pho tosynthetic response also showed a broad temperature optimum around 20 C. Vines wh ich were grown in 10 or 30 C conditions acclimatised rapidly when they were transferred to a 20 C growth temperature, and adjusted their photosynthetic rates within 24 days . Fruit growth in the kiwifruit was dependen t on current phot osynthates . Only negligible amounts of 1 4 C-label, which accumulated in the stems and roots of the vines from the previous season, were remobilized to support fruit growth. Kiwifruit leaves exported 1 4 C-assimilate when they were 60 % of full expansion , or 40 days from emergence . The principal source leaves which supplied the frui ts were the leaves which sub tended the fruits. On an intact shoot system , each subtending leaf supplied as much as 62 % of their total 1 4 C-assimilate exclusively to its own fruit. The fruit also received smaller amounts of 1 4 C-assimilate from some distal leaves via vascular connections wh ich linked at vii least, the n, n+5 , and n+8 nodes . However , this pat tern of 1 4 C translocation was altered when the frui ting shoot was pruned. Each fruit then received supplies of 1 4 C-assimilate from every distal leaf, plus an increased amount (78 % of total leaf 1 4 C) from its subtending leaf . The minimum leaf-fruit ratio to support normal fruit growth lies between 0.83:1 (86 cm2 ) and 1.7:1 (173 cm2 ). A shortfall in the supply of assimilate wi thin a fruiting shoot below this ratio was readily me t by surplus 14 C-assimilate from source leaves on adj acent fruit ing or non-fruiting shoots, up to 8 nodes distance away . It Vas probably because of this flexibility in the translocation of assimilate that kiwifruit leaves did not show any photosynthetic response to increased fruit demand for carbohydrate. Bo th fruit ing and non-fruit ing shoots had similar maxi mum photosynthetic rates - 2 - 1 of about 657 ugC02 m S . The fruit growth of a kiwifrui t, as determined by fruit volume or fresh weight, followed a double sigmoid pattern. Increases in frui t dry weight however were linear throughout the growth period . Final fruit sizes were partly determined by pre-anthesis fac tors , although vine management practices and pollination also had a significant influence on fruit growth. Fruits which developed from early flowers were as much as 31g larger than those from late flowers . The early viii flowers had bigger ovaries and were found on strong, vigorous shoots, which were mostly long shoots. It was also found that fruits produced on long shoots contained more viable seeds so tha t they carried larger fruits than those on short shoots, even though both developed from flowers with the same day of anthesis . The early stage of fruit growth on a fruit ing shoot was inhibited by large leaf numbers greater than 8 distal leaves , but this effect was diminished on vines older than 5 years . However, there was no effect of frui t number on fruit size wi thin a frui t ing shoot. Frui ts wi th similar numbers of seeds developed in synchrony wi th each other , whereas fruits with lower seed numbers were inhibited by those with higher seed numbers at adj acent positions .