UNIVERSITI PUTRA MALAYSIA

UNIVERSITI PUTRA MALAYSIA PHYSIOLOGICAL RESPONSES OF WINGED BEAN [PSOPHOCARPUS TETRAGONOLOBUS (L.) DC.] TO SUPPORT SYSTEMS AND RATOONING MD. MOTIOR RAHMAN FP 1998 6

PHYSIOLOGICAL RESPONSES OF WINGED BEAN [PSOPHOCARPUS TETRAGONOLOBUS (L.) DC.] TO SUPPORT SYSTEMS AND RATOONING MD. MOTIOR RAHMAN DOCTOR OF PHILOSOPHY UNIVERSITI PUTRA MALAYSIA 1998

PHYSIOLOGICAL RESPONSES OF WINGED BEAN [PSOPHOCARPUS TETRAGONOLOBUS (L.) DC.] TO SUPPORT SYSTEMS AND RATOONING By MD. MOT lor RAHMAN Thesis Submitted in Fulfilment of the Requirements for the Degree of Doctor of Philosophy in the Faculty of Agriculture Universiti Putra Malaysia June 1998

DEDICATED TO THE DEPARTED SOULS OF MY GRANDFATHER AND GRANDMOTHER

ACKNOWLEDGEMENTS I would like to express my deepest gratitude and sincere appreciation to Dr. Wan Mohamad Wan Othman, Associate Professor, Department of Agronomy and Horticulture, Faculty of Agriculture, Universiti Putra Malaysia, the Chairman of my supervisory committee, for his constant valuable guidance and support throughout the research and preparation of 'this thesis. His continuous advice and encouragement have helped me to develop my entire graduate career. I am also grateful to Dr. Wong Kai Choo, Professor, Department of Agronomy and Horticulture, Faculty of Agriculture, Universiti Putra Malaysia for his thoughtful suggestions in the preparation of thesis proposal, for his meticulous reading of the drafts, and for his advice and criticisms to further improve the final draft. I am especially thankful to Dr. Zulkifli Haji Shamsuddin, Associate Professor, Department of Soil Science and Deputy Dean (Research), Faculty of Agriculture, Universiti Putra Malaysia, for giving me the financial support for conducting field research and laboratory analyses. I have had the privileges of attending and presenting part of my thesis at the Second International Crop Science Congress, 17-24 November 1996, New Delhi, India and the National Soil Science Conference of Malaysia, 14-16 April, 1997, Ipoh, Perak, Malaysia due to his kind assistance. I am furthermore grateful for his careful and critical suggestions in the improvement of the thesis. iii

I would like to thank Dr. P. M. Chalk, Associate Professor and Reader, University of Melbourne, Australia (currently Head, Soil and Water Management and Crop Nutrition Section, IAEA, Vienna, Austria) and Dr. M. Quayum, Associate Professor, Department of English, Faculty of Modem Languages, Universiti Putra Malaysia for carefully editing the manuscript. Thanks are also due to Dr. Ridzwan Abdul Halim, Associate Professor and Head, Department of Agronomy and Horticulture, Faculty of Agriculture, Universiti Putra Malaysia for helping me with statistical analysis. I appreciate the help and cooperation of the following people who have made this study possible: Mr. Amir Hamzah Bin Ahmad Ghazali, Mr: Mahbub Shah Bin Gohar Shah, Mr. Azhar Bin Othman, Mr. Mazlan Bin Bangi, Mr. Abdul Aziz Bin Ismail, Mr. Khoiri Bin Kandar, Mrs. Mahani Binte Yahaya and Mr. Kamaruddin Bin Yusof for helping me in the use of portable photosynthesis meter, leaf area meter, Auto analyzer, Atomic Absorption Spectrophotometer, Spectrometer and Gas Chromatograph. Gratitudes are expressed to the field staff, Mr. Shahril Bin Abdul Rahman, for the technical assistance while conducting my field experiments. Among the Bangladeshi community in Malaysia, I would like to especially thank Mr. Shaheed Sohrawardi for taking field photographs, and Md. Lutfor Rahman and Md. Hafizul Haque for their assistance in the field study. iv

The research project was made possible by the financial support of Crop Diversification Programme (CDP), funded by the Canadian International Development Agency (eida), in collaboration with Bangladesh Agricultural Research Institute. I wish to gratefully acknowledge Dr. A.F.M. Maniruzzaman, Former Director (Research), Bangladesh Agricultural Research Institute for his constant encouragement and guidance to develop my research career on field crop research during the period of my service at the Bangladesh Agricultural Research Institute. Sincere thanks and heartfelt gratitude are also due to Dr. M. A. Mazed, Director General, Bangladesh Agricultural Research Institute for providing me the much needed moral support and encouragement during the period of my stay at the Bangladesh Agricultural Research Institute and in Malaysia. I am deeply indebted to my mother, brother and sister, my father-inlaw and mother-in-law and my uncle Mr. M. A. Maleque for their continuous inspiration and prayers for the success of my study. I am forever indebted to my beloved wife, Farzana Rahman and to my daughter Nabila for their sacrifices and patience during the course of my graduate study. I would not have been able to complete my study successfully without their understanding, unfailing support and inspiration. v

TABLE OF CONTENTS ACKNOWLEDGEMENTS... LIST OF TABLES... LIST OF FIGURES... LIST OF PLATES...... LIST OF APPENDICES... ABSTRACT... ABSTRAK.... Page iii xi xu XVI xvii xviii....... XXI CHAPTER.... I WTRODUCTION.... 1 Statement of Problem...,... 4 Objectives of the Study..... 5 IT ill REVIEW OF LITERATURE.... Biomass Accumulation and Partitioning... Leaf Area Index (LAI).... Net Assimilation Rate (NAR)... Relative Growth Rate (RGR)... Source Sink Relationship...,......... Harvest Index (HI)... Photosynthesis.... Solar Radiation... Nitrogen Accumulation and Partitioning... N Itrogen p" lxation... Support System... Ratooning...:.................. MA TERIALS AND METHODS..... 6 7 10 11 12 l3 15 16 19 20 24 30 32 35 Experimental Site, Cultural Practices and Crop Management.. 35 Support System............................................ 36 Measurement of Net Photosynthesis... 36 Measuremen( of Chlorophyll Content of Leaves... 38 Measurement of Solar Radiation Interception... vi 39

Recording of Leaf Senescence................... 40 Determination of Total Dry Matter, Leaf Area Index (LAI), Relative Growth Rate (RGR) and Net Assimilation Rate Page 40 (NAR)................................ Determination of N Concentration............. 41 Estimation of Nitrogen Fixation...... 42 Xylem Exudate Collection and Determination of Nitrogenous Solutes........................ 43 Seed Yield, Yield Attributes and Harvest Index.......... 45 Statistical Analysis... 45 IV EXPERIME NTALS.... 46 Experiment 1 Effects of Support Systems on Growth, Nitrogen Fixation and Seed Yield of Winged Bean......................................... 46 Materials and Methods... 47 Results................................. 49 Above Ground Dry Matter Accumulation......... 49 Partitioning of Dry Matter.................... < 53 Leaf Area Index................................... 55 Relative Growth Rate (RGR)... 57 Net Assimilation Rate (NAR)..................... 59 Chlorophyll Content of Leaves.................... 59 Net Photosynthesis........................... 61 Stomatal Conductance and Intercellular CO2 62 Concentration... Absorption of Photosynthetically Active Radiation (PAR) 64 Leaf Senescence..................................... 64 Nodule Dry Weight and Nitrogenase Activity....... 66 Pod Bearing Node and Inter-node Length... 70 Flowering and Seed Filling Period.............. 72 Seed Yield and Yield Attributes................... 72 Correlation Between Seed Yield, Yield Attributes and Some Relevant Characters... 74 Economic Analysis of\vinged Bean Grown on Different Support Systelns.... 77 Principal Component Analysis of Characteristics that Determine the Total Dry Matter................. 78 vii

Page Principal Component Analysis of Characteristics that 81 Determine the Nitrogenase Activity...... Principal Component Analysis of Characteristics that Contribute to Seed Yield......... 82 Discussion.............,..."...................... 85 Growth and Dry Matter Partitioning of Winged Bean Grown on Different Support Systems.................. 85 Nodulation and Nitrogenase Activity of Winged Bean Grown on Different Support Systems... 92 Seed Yield Attributes and Their Correlation of Winged Bean Grown on Different Support Systems...... 94 Experiment 2 Effects of Ratooning on Seed Yield of Winged Bean Grown With and without Support...,...................................... 97 Materials and Methods...................... 97 Results..... 99 Total Dry Matter Accumulation in Aerial Parts of Ratooned Winged Bean Grown on Support Systems... 99 Total Nitrogen Accumulation of Ratooned Winged Bean Grown on Support Systems... 105 Seed Yield of Ratooned Winged Bean Grown on Support Systems.... 110 Discussion...... 113 Experiment 3 Effects of Support Systems and Ratooning on Growth, Nitrogen Partitioning and Seed Yield of Winged Bean......... 116 Materials and Methods....................... 117 Results.................................... 118 Biomass Production of Ratooned Winged Bean Grown on Different Support Systems... 118 viii

Page Dry Matter Partitioning of Ratooned Winged Bean 121 Grown on Different Support Systems.... Leaf Area Index of Ratooned Winged Bean Grown on Different Support Systems...... 123 Relative Growth Rate (RGR) of Ratooned Winged Bean Grown on Different Support Systems..................... 125 Net Assimilation Rate (NAR) of Ratooned Winged Bean Grown on Different Support Systems................... 127.. Net Photosynthesis of Ratooned Winged Bean Grown on Different Support Systems............... 130 Solar Radiation Interception of Ratooned Winged Bean Grown on Different Support Systems...................... 132 Nodule Dry Weight and Nitrogenase Activity of Ratooned Winged Bean Grown on Different Support Systems...................... 134 Nitrogen Accumulation in Aerial Parts of Ratooned. Winged Bean Grown on Different Support Systems... Nitrogen Accumulation in plant parts of Ratooned Winged Bean Grown on Different Support Systems...... 141... 138 Nitrogen Partitioning of Ratooned Winged Bean Grown on Different Support Systems............. 145 Nitrogen (N) Concentration of Ratooned Winged Bean Grown on Different Support Systems..................... 147 N Solutes Concentration in Xylem Exudates of Ratooned Winged Bean Grown on Different Support Systems...... 149 Flowering and Seed filling Period of Ratooned Winged Bean Grown on Different Support Systems... 156 Seed Yield and Yield Attributes of Ratooned Winged Bean Grown on Different Support Systems............. 158 Discussion........................................... 164 Seed Yield of Ratooned Winged Bean Grown on Support Systems.............................................. 164 Nitrogen A ccumulation and Nitrogenase Activity of Ratooned Winged Bean Grown on Support Systems..... 165 Growth and Dry Matter Partitioning ' of Ratooned Winged Bean Grown on Different Support Systems... 167 v GENERAL DISCUSSIO N AND CO NCLUSIO N..... 173 ix

Page BIDLIOGRAPHY............................................ 178 APPENDICES............................... 193 VITA................................................ 220 A NOTE ON PUBLICATIONS...... 222 x

LIST OF TABLES Table Page 1 Stem and Leaf Dry Matter and Leaf to Stem Ratio at Different Growth Stages of Winged Bean Grown on Different Support Systems........................... 51 2 Seed Yield, Yield Attributes and Harvest Index (ill) of Winged Bean Grown on Different Support Systems........ 74 3 Relationship among Different Traits in Winged Bean...... 75 4 Cost Benefit Analysis of Winged Bean Grown on Different Support Systems......................... '" 77 5 Eigen Values and Proportions of Total Variation Among Nine Variables for Total Dry Matter (TDM) of Winged Bean as Explained by The First Four Principal Components........................................... 79 6 Characteristics of Total Dry Matter of Winged Bean Used in The Principal Component Analysis and The Eigen Vectors of Each Character on The First Four Principal Components.......................................... 80 7 Eigen Values and Proportions of Total Variation Among Five Variables for Nitrogenase Activity of Winged Bean as Explained by The First Two Principal Components.... 81 8 Characteristics of Nitrogenase Activity of Winged Bean Used in The Principal Component Analysis and The Eigen Vectors of Each Character on The First Two Principal Components............................................... 82 9 Eigen Values and Proportions of Total Variation Among Nine Variables for Seed Yield of Winged Bean as Explained by The First Two Principal Components........ 83 10 Characteristics of Seed Yield of Winged Bean Used in The Principal Component Analysis and The Eigen Vectors of Each Character on The First Two Principal Components............................................ 84 11 Seed Yield Attributes of Ratooned Winged Bean Grown on Different Support Systems...................... 162 xi

LIST OF FIGURES Page 1 Total Dry Matter Accumulation of Winged Bean Grown on Different Support Systems..... 50 2 Dry Matter Accumulation in Leaves, Stems, Petioles and Pods III Winged Bean Grown on Different Support Systems..... 52 3 Dry Matter Distribution of Winged Bean Grown on Different Support Systems................. 54 4 Leaf Area Indices of Winged Bean Grown on Different Support Systems..................'"... 56 5 Relative Growth Rate of Winged Bean Grown on Different Support Systems............................... 58 6 Net Assimilation Rate of Winged Bean Grown on Different Support Systems............... 58 7 Chlorophyll Content of Winged Bean Leaves Grown on Different Support Systems............. 60 8 Net Photosynthesis of Winged Bean Plants Grown on Different Support Systems.............. 60 9 Stomatal Conductance of Winged Bean Leaves Grown on Different ' 10 Intercellular CO2 Concentration of leaves of Winged Bean Grown on Different Support Systems... 63 11 Abso rption of PAR by Winged Bean Grown on Different Support Systems............................... 65 12 Leaf Senescence of Winged Bean Grown on Different Support Systems........... 65 13 Nodule Mass Accumulation of Winged Bean Grown on Different Support Systems....................... 68 14 Nitrogenase Activity of Nodulated Root Systems of Winged Bean Grown on Different Support Systems... 68 xii

15 Interrelationship Between Nitrogenase Activity with Nodule Dry Weight, Seed Yield, Net Photosynthesis and Page Solar Radiation Interception....................... 69 16 Pod-Bearing Node and Inter-node Length of Winged Bean Vines Grown on Different Support Systems.......... 71 17 Flowering and Seed Filling Period of Winged Bean Grown on Different Support Systems................ 73 18 Relationship Between Total Dry Matter and Seed Yield per Plant.................. 76 19 Relationship Between Leaf Area Indices and Total Dry Matter............................... 76 20 Total Dry Mat ter Accumulation of Ratooned Winged Bean Grown on Support Systems...................... 100 21 Leaf Dry Matter Accumulation of Ratooned Winged Bean Grown on Support Systems.................... 102 22 Pod Dry Matter Accumulation of Ratooned Winged Bean Grown on Support Systems.......................... 103 23 Total N Accumulation of Ratooned Winged Bean Grown on Support Systems.................................. 106 24 Leaf N Accumulation of Ratooned Winged Bean Grown on Support Systems............... 108 25 Pod N Accumulation of Ratooned Winged Bean Grown on Support Systems......... 109 26 Seed Yield of Ratooned Winged Bean Grown on Suppor t Systems....... III 27 Total Dry Matter Accumulation of Ratooned Winged Bean Grown on Support Systems... 120 28 Dry Matter Distribution of Ratooned Winged Bean Plants Grown on Support Systems................. 122 29 Leaf Area Indices of Ratooned Winged Bean Grown on Support Systems.................. 124 xiii

Pa ge 30 Relative Growth Rate of Ratooned Win ged Bean Grown on Support Systems............ 126 31 Net Assimilation Rate of Ratooned Win ged Bean Grown on Different Support Systems............ 129 32 Net Photosynthesis of Win ged Be an Grown on Suppor t Systems.................. 131 33 Net Photosynthesis of Ratooned and Non-Ratooned Win ged Bean Grown on Support Systems................. 131 34 Solar Radiation Interception of Win ged Bean Grown on Support Systems... 133 35 Solar Radiation Interception of Ratooned and Non- Ratooned Win ged Bean Grown on Support Systems...... 133 36 Nodule Dry Mat ter of Ratooned Win ged Bean Grown on Suppor t Systems.............. 135 37 Nitro genase Activity ofratooned Win ged Bean Grown on Support Systems.... 137 38 Total N Accumulation of Ratooned Win ged Bean Grown on Support Systems...'"... 140 39 Leaf N Accumulation of Ratooned Win ged Bean Grown on Suppor t Systems............................ 143 40 Pod N Accumulation of Ratooned Win ged Bean Grown on Support Systems...... 144 41 Relative Distribution of Nitro gen amon g Ratooned Win ged Bean Plant Or gans Grown on Support Systems '" 148 42 Allantoin Concentration in Xylem Exudates of Ratooned Win ged Bean Grown on Support Systems......... 150 43 Nitrate-N Concentration in Xylem Exudates of Ratooned Win ged Bean Grown on Support Systems........... 151 44 Amino-N Concentration in Xylem Exudates of Ratooned Win ged Bean Grown on Support Systems... 153 xiv

Page 45 Relative Abundance of Vari ous Soluble N Fracti ons in Rat ooned Winged Bean Xylem Exudates as Affected by Supp ort Systems....... 154 46 Relati onship Between Nodule Dry Weight and Allant oin Concentrati on in Xylem Ex udates of Rat ooned Winged Bean..... 155 47 Fl owering and Seed Filling Peri od of Rat ooned Winged Bean Gr own on Supp0l1 Systems....... 157 48 Seed Yield of Ratooned Winged Bean Gr own on Supp ort Systems........ 159 49 Relati onship Between Total N Accumulati on and Seed Yield of Ratooned Winged Bean Gr own on Supp ort Systems........................... 161 50 Relati onship Between Total Dr y Matter and Total N Accumulati on of Rat ooned Winged Bean Gr own on Supp ort Systems... 161 xv

LIST OF PLATES P 3.1 Diagram Showing the Construction of Support System... 37 4.1 A Close up View of Winged Bean Plants at Mid Pod Formation Stage........................... 48 A.2 A Close up View of Winged Bean Root Nodules....... 67 xvi

LIST OF APPENDICES Appendix Page 1 Analyses of Variances of Total Dry Matter Accumulation in Whole Plant and its Component Parts....... 194 2 Analyses of Variances of Leaf Area Index, Relative Growth Rate and Net Assimilation Rate and Chlorophyll Content of Leaf................................................... 197 3 Analyses of Variances of Net Photosynthesis, Stomatal Conductance, Intercellular C02 Concentration, Photos ynthetically Active Radiation (PAR) and Leaf Senescence......... 199 4 Analyses of Variances of Nodule Mass Accumulation, Nitrogenase Activity, Seed Yield and Yield At tributes.... 20 I 5 Economic Analysis of Winged Bean Grown on Different Suppor t Systems......... 203 6 Analyses of Variances of Total Dry Matter Accumulation in Aerial Plant Par ts of Ratooned Winged Bean..... 204 7 Analyses of Variances of Total N Accumulation in Whole Plant and its Component Par ts ofratooned Winged Bean.. 206 8 Analyse s of Variances of Total Dry Matter Accumulation in Whole Plant, Leaf Area Index, Relative Growth Rate, Net Assimilation Rate, Net Photosynthesis, and Solar Radiation Interception of Ratooned Winged Bean........... 208 9 Analyses of Variances of Nodule Dry Matte r, Nitrogenase Activity and Total N Accumulation in Whole lant and its Component Par ts of Ratooned Winged Bean................. 212 10 Nitrogen Concentration (mg g- l ) of Ratooned Winged Bean Plant Parts as Influenced by Plant Age under Support Systems... 216 11 Analyses of Variances of N Solutes Concentrations in Xy lem Exudates ofratooned Winged Bean...... 217 12 Analyses of Variances of Seed Yield and Yield At tributes of Ratooned Winged Bean............... 219 xvii

Abstract of thes is submitted to the Senate ofuniversiti Putra Malaysia in fulfilment of the requirements for the degree of Doctor of Philosophy PHYSIOLOGICAL RESPONSES OF WINGED BEAN [PSOPHOCARPUS TETRAGONOLOBUS (L.) DC.l TO SUPPORT SYSTEMS AND RATOONING By MD. MOTIOR RAHMAN June 1998 Chairman: Faculty: Associate Professor Dr. Wan Mohamad Wan Othman Agriculture Winged bean is an indeterminate, climbing, perennial legume that needs support to achieve high yields. The ma jor constraint to large scale production of winged bean is the need for trellising which incurred an additional cost of production. After harvesting of young or mature pods plants can be cut and the pollarded root stock produces a ratoon crop. Ratooning, a new technique for seed production of winged bean, can reduce the initial expenditure on suppo rt structures. Therefore, these studies on the effects of support systems and ratooning on growth and seed production of winged bean were conducted under humid tropical field conditions to document some experimental evidence. Results from the first experiment revealed that when compared to unsupported control, support height of 1 and 2 m caused a significant increase in leaf area xviii

index (LAI), net photosynthesis, relative growth rate (RGR), nodule activity, solar radiation interception (SRI), pattern of dry matter accumulation and partitioning and consequently the seed yield of winged bean. Plants grown on a support height of2 m had enhanced leaf growth, pod number and total dry matter yield when compared to those on support height of I m and unsupported plants. In the subsequent experiment, the root stock of the main crop was cut off at 126, 140, 154 and 168 days after germination (DAG) and the ratooned crops maintained for the next two crop cycles (126 days/crop cycle). The results suggested that ratooning of winged bean at 126 or 140 DAG would lower the investment expenditure on support structures and produced the highest cumulative seed yield per unit area per unit time. In the third experiment, winged bean plants were grown on support heights ofo, I and 2 m and ratooned at 133, 154 and 175 DAG. There were three crop growth cycles continued in a unit area over time. Support systems and ratooning had a significant influence in increasing nitrogen fixation, nitrogen accumulation in leaves and N partitioning to pods, LAI, net assimilation rate (NAR), net photosynthesis, SRI and consequently the plants growth patterns and seed yield. Plants grown on 2 m support height and ratooned at 133 DAG recorded the highest cumulative seed yield (6.26 t ha- 1 ), largely associated with increased number of pods per plant and leaf dry matter, leaf N and net photosynthetic efficiency. The lowest cumulative seed yield (1.28 t ha- 1 ) was xix

obtained from unsupported control plants and ratooned at 175 DAG. The data also indicated that winged bean plants grown on support height of 2 m with appropriate ratooning practice is teclmologically feasible and economically viable. Principal component analysis gave a clear direction of each desired variable. Nodule mass (NM), leaf dry matter (LDM) and number of pods per plant (PP) are the most important components of nitrogenase activity (NA), total dry matter and seed yield, respectively. Based on the above findings it is evident that the indeterminate climbing winged bean grown on a 2 m support height accumulated substantial amounts of dry matter and N compared with those on support height 1 m and unsupported plants. It is concluded that in addition to dry matter accumulation, partitioning of leaf dry matter and leaf N play an important role in vegetative growth and seed yield of winged bean. Seed production of winged bean can be increased by more than 5-fold (6.26 t ha- 1 ) by adopting a 2 m support height and appropriate ratooning practices. The optimum time of ratooning at 133 days after germination under support system of 2 m height maximized seed yield per unit area per year, thereby spreading'out the cost of trellising over three crop cycles. xx

Abstrak tesis yang kemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi Keperluan untukijazah Doktor Falsafah RESPON FISIOLOGI KACANG BOTOR [PSOPHOCARPUS TETRA GONOLOBUS (L.) DC.] TERHADAP SISTEM SOKONGAN DAN CANTASAN Oleh MD. MOTIOR RAHMAN Jun 1998 Pengerusi: Faculti: Profesor Madya Dr. Wan Mohamad Wan Othman Pertanian Kacang botor adalah tanaman saka "indeterminate", menjalar dan memerlukan sokongan untuk pengeluaran hasil yang tinggi. Masalah utama yang dihadapi untuk pengeluaran kacang botor secara besaran ialah keperluan penyediaan sokongan yang menyebabkan pertambahan kos pengeluaran. Selepas penuaian pod muda at u tua, pokok boleh dipotong dan tunggul pokok akan menghasilkan satu tanaman cantasan (ratoon crop). Cantasan adalah satu teknik baru didalam proses pengeluaran biji kacang botor dan ia dapat mengurangkan kos pembinaan sistem sokongan tersebut. Oleh yang demikian, kajian ini telah dijalankan diladang berkeadaan lembab tropika untuk memungut bukti tentang kesan sistem sokongan dan cantasan terhadap pertumbuhan dan pengeluaran biji kacang botor. Keputusan daripada eksperimen pertama menunjukkan bahawa berbanding dengan kawalan, sokongan setinggi 1 dan 2 m meningkatkan dengan bererti indek keluasan daun (IKD), kadar fotosintisis bersih, kadar pertumbuhan xxi

bandingan (KPB), aktiviti nodul, intersepsi radiasi solar (IRS), corak pengumpulan berat kering, pembahagian bahan kering dan akhimya hasil biji kacang botor. Tanaman diberi sokongan setinggi 2 m mempunyai peningkatan dalam pertumbuhan daun, bilangan pod dan jumlah berat kering yang lebih tinggi berbanding dengan pokok diberi sokongan 1 m dan tanpa sokongan. Dalam experimen yang seterusnya, bahagian pangkal pokok asal telah dipotong pada 126, 140, 154 dan 168 hari selepas percambahan (HSP) dan tanaman cantasan diselenggarakan untuk 2 musim berikutnya (126 hari per pusingan tanaman). Keputusan yang diperolehi mencadangkan bahawa proses cantasan kacang botor pada 126 atau 140 HSP dapat mengurangkan kos untuk struktur sokongan dan menghasilkan hasil biji gabungan tertinggi per unit kawasan per unit masa. Bagi expenmen yang ketiga, kacang botor telah ditanam melibatkan sokongan pada ketinggian 0, 1 dan 2 meter dan dicantas pada hari ke-133, 154 dan 175 selepas percambahan. Terdapat tiga pusingan tumbesaran tanaman dalam satu unit kawasan dalam satu jangkamasa. Sistem sokongan dan cantasan memberi kesan yang bererti dalam meningkatkan pengikatkan nitrogen, pengumpulan N dalam daun dan pembahagian nitrogen kepada pod, indeks keluasan daun, kadar assimilasi bersih (KAB), kadar fotosintisis, intersepsi radiasi solar dan akhimya corak tumbesaran pokok dan hasil biji. Pokok diberi sokongan 2 m tinggi dengan cantasan pada minggu ke-19 selepas percambahan xxii

merekodkan hasil biji gabungan yang tertinggi (6.26 t ha- l ), yang berkaitan dengan penambahan bilangan pod per pokok, berat kering daun, kandungan N daun dan keberkesanan proses fotosintisis. Hasil biji kumulatif yang terrendah (1.28 t ha- l ) diperolehi daripada tanaman tanpa sokongan yang'dicantas pada 175 HSP. Keputusan penyelidikan ini menunjukkan juga tanaman kacang botor yang diberi sokongan 2 m tinggi dengan am alan cantasan yang sesuai adalah teknologi yang mudah dan memberi keuntungan yang lumayan. Analysis komponen utama memberi hal a yang jelas terhadap angkubah yang diingini. Berat nodul (BN), berat kering daun (BKD), bilangan pod per pokok (BPP) adalah komponen yang penting bagi aktiviti nitrogenase (AN), jumlah bahan kering dan hasil biji, tiap-tiap satu. Berdasarkan hasil kajian diatas, adalah jelas bahawa kacang botor yang ditanam dengan sokongan pada ketinggian 2 m boleh menambahkan lebih banyak bahan kering dan N berbanding dengan pokok diberi sokongan ketinggian 1 m dan tanpa sokongan. Dapat disimpulkan bahawa selain penambahan hasil berat kering, pembahagian bahan kering daun dan kandungan N daun, memain peranan penting dalam tumbesaran vegetatif dan hasil biji kacang botor. Pengeluaran biji kacang botor dapat ditingkatkan lebih 5-kali ganda (6.26 t ha- l ) dengan menggunakan sokongan setinggi 2 m dan cantasan yang sesuai. Masa cantasan yang optima pada 133 HSP dengan sokongan 2 m tinggi mengeluarkan hasil xxiii