The Physiology Of Cassava Flower Development
DOWNLOAD
Download The Physiology Of Cassava Flower Development PDF/ePub or read online books in Mobi eBooks. Click Download or Read Online button to get The Physiology Of Cassava Flower Development book now. This website allows unlimited access to, at the time of writing, more than 1.5 million titles, including hundreds of thousands of titles in various foreign languages. If the content not found or just blank you must refresh this page
The Physiology Of Cassava Flower Development
DOWNLOAD
Author : Deborah Ngunengen Oluwasanya
language : en
Publisher:
Release Date : 2020
The Physiology Of Cassava Flower Development written by Deborah Ngunengen Oluwasanya and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Cassava sexual reproduction is important for breeding improved cassava cultivars as it is the primary means for genetic recombination. Several challenges hinder successful cassava breeding, including: delay in flower initiation, abortion after successful initiation, low number of flowers produced per inflorescence, low proportion of flowers that are female, and poor fruit and seed set, especially in genotypes with traits of agronomic importance. In this dissertation, I focused on the challenge of flower initiation and low female flower numbers. To evaluate factors affecting flower initiation and genotype by environmental interactions, plants were grown under two Nigerian field environments (Ubiaja and Ibadan) and three controlled temperature conditions (22_C/18_C, 28/24_C and 34/30_C (day/night)). This study showed that the Ubiaja field and 22_C/18_C (day/night) environments were favorable for cassava flowering while the Ibadan field and warmer temperatures had a delaying effect. Early flowering genotypes tended to be environmentally insensitive while late genotypes were sensitive to the delaying effect of unfavorable environments. To elucidate methods by which flower numbers can be increased in the field, treatments with anti-ethylene growth regulator silver thiosulfate (STS) or pruning fork-type branches increased flower abundance without changing female to male ratios. Application of the synthetic cytokinin benzyladenine (BA) increased the percentage of female flowers to over 80%. The three-way treatment combination of pruning + STS + BA produced the largest number of female flowers, with STS and pruning working additively to increase total flower numbers and BA increasing the proportion of female flowers. Transcriptomic analysis of gene expression with RNA-seq showed that all conditions favoring cassava flowering (Ubiaja field, 22_C/18_C and pruning+STS+BA treatments) downregulated expression of flowering repressor gene TEMPRANILLO1. There were also complex changes to abscisic signaling genes under all conditions studied. The transcriptome of the pruning+STS+BA treatment additionally showed downregulated gibberellin signaling. Finally, analysis of vegetative growth and nighttime carbohydrate export from leaf showed that the flower enhancing effect of plant growth regulators did not modify photosynthate partitioning. Based on these recent findings and that of our Cornell-led project, the treatment strategy using pruning+STS+BA to enhance cassava female flower and fruit development offers the potential to enhance breeding productivity by many cassava breeding programs.
Physiological Causes Of Yield Variation In Cassava Manihot Esculenta Crantz
DOWNLOAD
Author : H. J. Veltkamp
language : en
Publisher:
Release Date : 1986
Physiological Causes Of Yield Variation In Cassava Manihot Esculenta Crantz written by H. J. Veltkamp and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1986 with Gardening categories.
This thesis begins with a literature review in which the available information on the physiological determinants of the yield of cassava storage roots is described.
The Physiology Of Flowering
DOWNLOAD
Author : Jean-Marie Kinet
language : en
Publisher: CRC Press
Release Date : 2018-01-10
The Physiology Of Flowering written by Jean-Marie Kinet and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-01-10 with Science categories.
The present work is organised such that the whole phenomenon of flowing is divided into two major steps: 1. the initiation of flower primordia and 2. The development of these primordia into mature flowers until anthesis. With this volume aiming to to provide a balanced account of themost important and recent contributions in all aspects of the subject.
Growth Physiology Of Cassava
DOWNLOAD
Author : L. A. Hunt
language : en
Publisher:
Release Date : 1977
Growth Physiology Of Cassava written by L. A. Hunt and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977 with Cassava categories.
Physiological And Developmental Changes In Cassava Manihot Esculenta Crantz Under Water Deficit
DOWNLOAD
Author : Alfredo A. C.. Alves
language : en
Publisher:
Release Date : 1998
Physiological And Developmental Changes In Cassava Manihot Esculenta Crantz Under Water Deficit written by Alfredo A. C.. Alves and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.
Cassava (Manihot esculenta Crantz) is an important food crop in the tropics. It is widely used in drought-prone climates, but little is known about the mechanisms by which cassava responds to water deficit environments. Cassava genotypes from five climatic zones of Brazil were grown in greenhouse conditions and subjected to water deficit and recovery treatments during the vegetative growth stage. In response to waterdeficit, cassava leaves rapidly accumulated the plant hormone abscisicacid (ABA) and correspondingly halted leaf expansion growth. Young leaves accumulated more ABA than mature leaves. Recovery was rapid: one day after rewatering, ABA concentrations returned to control levels. Other studies indicated that stomatal closure also occurred early duringwater deficit and recovered rapidly after rewatering.
The Physiology Of Flowering
DOWNLOAD
Author : Bernier
language : en
Publisher: CRC Press
Release Date : 2018-05-04
The Physiology Of Flowering written by Bernier and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-05-04 with Science categories.
The present work is organised such that the whole phenomenon of flowing is divided into two major steps: 1. the initiation of flower primordia and 2. The development of these primordia into mature flowers until anthesis.
The Physiology Of Flowering
DOWNLOAD
Author : Georges Bernier
language : en
Publisher:
Release Date : 1981
The Physiology Of Flowering written by Georges Bernier and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1981 with Plant physiology categories.
The initiation of flowers; Transition to reproductive growth.
Cassava
DOWNLOAD
Author : R. J. Hillocks
language : en
Publisher: CABI
Release Date : 2002
Cassava written by R. J. Hillocks and has been published by CABI this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Technology & Engineering categories.
Cassava is a major tropical tuber crop found throughout the tropics (India, Oceania, Africa and Latin America). Hitherto, there has been no single text covering all aspects of cassava biology, production and utilization. This book fills that gap, representing the first comprehensive research level overview of this main staple crop. Chapters are written by leading experts in this field from all continents. The book is suitable for those working and researching in cassava, in both developed and developing countries, as well as advanced students.
Towards Identifying The Physiological And Molecular Basis Of Drought Tolerance In Cassava Manihot Esculenta Crantz
DOWNLOAD
Author : Rosemary Wanja Mutegi-Murori
language : en
Publisher: Cuvillier Verlag
Release Date : 2010-02-10
Towards Identifying The Physiological And Molecular Basis Of Drought Tolerance In Cassava Manihot Esculenta Crantz written by Rosemary Wanja Mutegi-Murori and has been published by Cuvillier Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-02-10 with Science categories.
Drought is one of the most important factors limiting crop production in sub-Saharan Africa. This has detrimental effects to the people living in this region, and whose population is increasing more rapidly than their domestic food production. Noticeably, pressure on agricultural land has continued to intensify. Cassava is one of the staple crops with remarkable tolerance to drought. It is adapted to diverse and poor soil conditions, in addition to its flexibility in planting and harvesting times. Understanding its physiological and molecular basis of drought tolerance may help to target the key traits that limit crop yield under drought conditions. To improve our understanding on drought tolerance mechanisms in cassava, the project "Identifying the physiological and genetic traits that make cassava one of the most drought-tolerant crops" was initiated in 2005 by the Brazilian Agricultural Research Corporation (Embrapa) in collaboration with the International Center for Tropical Agriculture (CIAT); the International Institute of Tropical Agriculture (IITA); Cornell University and University of Goettingen. The ultimate goal of the project was to identify morphological, physiological and molecular traits related to drought tolerance mechanisms in cassava for further progress, and for their application in cassava and other crop breeding programs. The present study was conducted within the framework of this project with 31 African cassava germplasm accessions from IITA and a mapping population developed at CIAT. The objectives of this study were, 1) To develop a protocol for hardening and rapid micro-propagation of cassava plantlets under local, low-cost conditions; 2) To identify agro-morphological attributes that are related to drought tolerance in cassava; 3) To identify drought-tolerant and drought-susceptible cassava germplasm from a selection of African accessions; 4) To identify secondary traits that could be used for phenotyping breeding materials for drought tolerance; 5) To screen the CIAT mapping population with simple sequence repeats (SSR) and expressed simple sequence repeat (ESSR) markers for linkage analysis. Thirty one putative drought-tolerant and drought-susceptible African cassava germplasm accessions from IITA were micro-propagated using direct and in-direct techniques, at Kenya Agricultural Research Institute (KARI), Nairobi, Kenya. In direct micro-propagation, plantlets were hardened using vermiculite and multiplied through nodal cuttings. In in-direct micro-propagation, plantlets were first multiplied through sub-culturing and later hardened. The direct micro-propagation method had a higher multiplication rate. The number of plantlets obtained in 7 months using the direct method were 1173 as compared to 722 attained using the in-direct micropropagation. Rapid micro-propagation through nodal cuttings was cheaper in terms of consumables and an effective alternative to enhance rates of multiplication, over the in-direct method and the more conventional technique like the use of stem cuttings. Agronomic and morphological evaluation of contrasting African cassava germplasm accessions was carried out in water-stressed and well-watered environments at 5 time points. The trial was conducted at the experimental field of KARI, Kiboko Research Station in Makindu, Eastern Kenya, a site characterized by Acri-orthic Ferralsol soil. Analysis of variance was performed using the agronomic and morphological data, and broad sense heritability was estimated. In general, significant differences were observed among the accessions, suggesting a strong genetic basis for the phenotypic variation observed. Variation was also notable in water-stressed and well-watered environments for a majority of traits evaluated. This was due to the artificial water applied since, during the trial period, there was hardly any rainfall. At harvest, leaf length and width of certain accessions at the water-stressed site approached that of the well-watered treatment. On average, the estimated mean percentage leaf retention was high in the well-watered treatment. However, leaf retention in some of the accessions assessed was almost the same in both treatments. These accessions tended to produce higher yields. Thus, it may be desirable to select for higher leaf retention when developing varieties adapted to dry areas. The range of yields under stress was from 3.3 to 36.7 kg/m2, whereas, under the well-watered treatment, it was smaller: 28.3 to 53.3 kg/m2. Differences among accessions in yield and overall above-ground fresh biomass showed that these are important primary traits to phenotype germplasm under favorable and water-stress conditions. In addition, 4 accessions G26, G11, G8 and G31 were more tolerant than the rest of the genotypes evaluated, calling for further research and their involvement in agricultural experimentation under drought-prone conditions. Considering relationships between traits, genotype ability for both accumulation of above-ground fresh biomass and to partition carbon into roots (harvest index) were among the traits most correlated with root yield. However, accessions, environment and the interaction of both influenced the traits strongly. Thus, it is important that agro-morphological field trials be conducted in several locations for several seasons for effective evaluation of their influences on traits that might be relevant for phenotypically assessing drought tolerance. Unlike for agro-morphological traits, where a drought-tolerant accession could be identified from the yield, which is of primary concern, selection of an outstanding accession in a water-limited environment using metabolic traits was not achieved in this study. Maybe the well-watered plants experienced an incipient stress due to low humidity, symptomless diseases or nutrient deficiency, which was not ascertained in this study. Despite this, significant differences were observed between the waterstressed and well-watered treatments for the traits evaluated, except protein and amylose content. Performance in individuals was variable, although insignificant differences were observed between the different stress phases. Changes in sugar concentration have a role in the drought-tolerance of the accessions evaluated, although, their relative contribution to drought stress could not be determined from the available data. Further work is imperative to identify and quantify sugar concentrations in relation to osmotic adjustment in these accessions. In addition, further research to determine the time course of ABA accumulation, as a cassava plant goes from its young stage to aging, is required so as to know the stage at which ABA data are most informative. Two genetic linkage maps were constructed using a South American mapping population of 228 individuals derived from a cross between a drought-tolerant and a drought-susceptible parent. A set of 377 simple sequence repeats (SSR) and expressed simple sequence repeats (ESSR’s) were utilized for the initial polymorphism screening. Differences in map size, interval, number and mean distance between markers were apparent between the two maps. The female map had 14 linkage groups as compared to 13 in the male map. Twenty seven allelic bridges were noticeable between the two maps. In addition, 25 markers showed collineality with other available cassava maps. Forty six markers, whose map distances had not been determined previously, were mapped in this study. These maps form an important platform upon which to characterize the genetic basis of drought tolerance in cassava. Continued addition of more markers in these maps will refine the utility of the resource for future cassava breeding efforts. In conclusion, four African cassava accessions apparently have the ability to withstand severe drought. However, a majority of the accessions evaluated gave poor response in adaptability to water-limited conditions. This suggests that further agroecologically based research is required on these materials, since they represent diverse improved accessions from IITA breeding activities. This, coupled with markerassisted genetic analysis, would be an appropriate approach for the identification of drought-tolerant accessions.
Physiological And Developmental Changes In Cassava Manihot Esculenta Crantz Under Water Deficit
DOWNLOAD
Author : A. A. C. Alves
language : pt-BR
Publisher:
Release Date : 1998
Physiological And Developmental Changes In Cassava Manihot Esculenta Crantz Under Water Deficit written by A. A. C. Alves and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.
Introdução; General aspects of cassava; Cassava distribuition and production; Cassava and drought tolerance; Responses to water deficit; Abscisic acid and leaf growth in cassava genotypes under water deficit; Water dificit effect on cassava leaf growth, cell division, and cell expansion; Abscisic acid accumulation and osmotic adjustment in cassava under water deficit.