ABSTRACT
The patterns of gene effects on agronomic and some quality traits of eight genotypes of
rice (Oryza sativa L.) and their progenies were studied using Diallel analysis method 1
involving parents, F1 hybrids and their reciprocals. The eight genotypes studied were
selected for their agronomic performance and protein content from thirty genotypes
evaluated in a randomized complete block design and replicated three times at the
Teaching and Research Farm of the Federal University of Technology, Owerri, Nigeria
during the planting seasons of 2005 and 2006. The results of the Diallel analysis
conducted during the 2007 planting season indicated larger magnitude of additive
components of variance in attributes like number of tillers per plant, number of days to
anthesis, panicle length , number of secondary branches per panicle, 1000-seed weight,
grain width and grain length/grain width ratio. Non-additive variance was more important
for plant height at flowering, number of seeds per secondary branch of panicle, grain
length and percentage protein content. The nature and magnitude of general combining
ability(GCA) and specific combining ability(SCA) effects, as well as the direction of
heterosis assessed by the SCA effects, seemed to differ for different traits and various
cross combinations. No parental line consistently had negative SCA effects for all the
traits. Additive gene effects with high GCA values could be exploited in WITA 4 and
Max for higher tillering ability, NERICA 1, Fofifa 16 and WAB 96-1-1 for earliness;
WITA 4 and NERICA 1 for production of hybrids for greater number of secondary
branches per panicle; CT 7127-49 and EMPASC 105 for development of hybrids with
greater number of spikelets per panicle; NERICA 1, CT7127-49 and EMPASC 105 for
producing hybrids with more fertile grains; CT7127-49 and NERICAI for developing
progenies with more seeds per secondary branch of panicle; IR57689-73 and Fofifa 16
for 1000-seed weight and CT 7127-49 and WITA 4 for developing long and fine grains.
WITA 4 and EMPASC 105 were observed to be semi-dwarfs and offer themselves as
candidate genotypes for reduction of plant height to reduce stem lodging and increase
yield. The phenotypic generation means of the parental lines (P1 and P2), F1 and
reciprocal cross and the BC1 and BC2, evaluated during the 2009 planting season for the
study on genetic effects of the characters on the breeding lines generated, indicated that
the F1 generation means were higher than their mid-parent values especially for
percentage protein content. The F1 and F2 generation means were not significantly
different in the majority of the cases except for lowland x upland and upland x lowland
hybrids for percentage fertile spikelets and numbers of spikelets per panicle. Varied
genetic effects were observed on the characters for generation mean analysis on six
parameter model. Additive and dominance as well as epistatic gene effects were involved
in the inheritance of most characters. Digenic interactions were significant for most of the
traits. Presence of significant dominance effect combined with duplicate epitasis
restricted the scope for simple selection for most of the characters. Reciprocal and
maternal effects were also implicated for most of the traits.
TABLE OF CONTENTS
Title
Page
Title Page – – – – – – – – – –
i
Certification – – – – – – – – – –
ii
Dedication – – – – – – – – – –
iii
Acknowledgement – – – – – – – – –
iv
List of Publications – – – – – – – – –
v
Table of Contents – – – – – – – – –
vi
List of Tables – – – – – – – – – –
viii
Abstract – – – – – – – – – –
xii
INTRODUCTION – – – – – – – – –
1
LITERATURE REVIEW – – – – – – – –
4
Agronomy of Rice – – – – – – – – –
4
Rice Quality Criteria – – – – – – – – –
5
Nutritional Composition of Rice – – – – – – –
6
Varietal Influence on Nutrient Composition of Rice – – – – –
6
Biological Evaluation of Rice Protein – – – – – –
7
Genetic Analysis of Quality Traits in Rice – – – – – –
7
Crossing Method – – – – – – – – –
8
MATERIALS AND METHODS – – – – – – –
10
Sources of Planting Materials – – – – – – – –
10
Experiment I(Field Evaluation of 30 Genotypes Rice of select Parental Materials –
10
Experiment II (Laboratory Analysis for the Determination of the Proximate,
Mineral and Grain Physical Characteristics of the 28 Genotypes of Rice) – –
13
Statistical analysis – – – – –
14
9
Experiment III (Production of Hybrid seeds through Diallel Crossing Method) –
17
Experiment IV (Field Evaluation of F1 Hybrids and Production of Backcrosses) – –
18
Experiment V (Field Evaluation of Parents, F2’s and Backcrosses) – – –
18
Statistical analysis – – – – – – – –
18
Diallel Cross Analysis – – – – – – – –
19
Analysis of the Gene effects on the characters – – – –
21
RESULTS – – – – – – – – –
22
Evaluation of 30 Genotypes to select Suitable Parents – – – – –
22
Agronomic Characteristics – – – – – – – –
22
Laboratory Analysis (Proximate and Mineral Component Determination) – –
…………………………………….. 28
Classification of the Genotypes using Amylose and Grain Physical characters –
36
Variability Parameters – – – – – – – –
……………………….. 38
Estimates of Phenotypic and Genotypic Variance – – – – –
……………………….. 38
Combined Analysis of variance – – – – – – –
……………………….. 38
Coefficient of variation – – – – – – – –
……………………….. 40
Heritability – – – – – – – – – –
…………….43
Genetic Advance – – – – – – – – –
43
Correlation Studies- – – – – – – – – –
46
Diallel Analysis – – – – – – – –
52
Evaluation of the F1 and F2 generations for Heterosis in Percentage Protein Content
85
Phenotypic Generation Mean Performance – – – – –
89
Estimates of Gene effects on Agronomic and Physicochemical Characteristics of
the Genotypes – – – – – – – – – –
100
DISCUSSION – – – – – – – –
112
SUMMARY AND CONCLUSION – – – – –
142
10
REFERENCE – – – – – – – – –
……………. 148
APPENDICES – – – – – – – – –
……………. 166
CHAPTER ONE
INTRODUCTION
Rice (Oryza sativa L.) is a staple food for billions of people in the world. Kennedy
et al. (2002) reported that it is the predominant staple food for at least 33 developing
countries of the world, providing 27%, 20% and 3% of their dietary energy, protein and
fat supply respectively. Muller (1984) had earlier reported that one-third of the world’s
population depended on rice for over half of their caloric and protein requirements then.
This may have informed why rice production, in much of the world, increasingly focuses
on optimizing grain yield, reducing production costs and minimizing pollution risks to the
environment. In the period of 1961 to 1981, the average world rice harvest increased from
2.23 t ha-1 to 2.86t ha-1, representing a mean increase of 23%. The usefulness of rice is
indeed universal, because man benefits not only from the starchy grains but it could also
be utilized in the production of starch, alcoholic beverages and soft drinks. Rice
consumption in West Africa has been reported to be increasing (Watanabe, 1998),
thereby, compensating for the reduction of the consumption of other cereals. Global
consumption of rice continues to outpace its production. This is so because of unabated
population growth. The World Bank Population Project (1995) reported that the global
demand of rice then was at 524 million tonnes and projected that it would increase to over
700 million tones. In Nigeria, rice production in 2005 and 2006 farming seasons forecasts
was 2.7 million metric tonnes (MT) from 2.3 million metric tonnes in 2004-2005 seasons
(Oryza Market Report, 2005). The current awareness of the Nigerian government for the
adoption of new rice varieties to help boost rice production is highly commendable.
Rice breeding efforts over the past three decades have been concentrated on the
development of high-yielding rice varieties to meet the food need of humanity. Hybrid
rice offers the potentials to boost rice yield potentials. Virmani and Peng (1999) reported
18
that it has a yield advantage of 15-20% over conventional high-yielding varieties. Choice
of outstanding parents with favourable alleles will no doubt offer opportunity for greater
success for higher yields. Improvements in rice quality are very crucial in meeting the
demands of consumers for healthy, high quality food (Kennedy et al., 2002). Koutroubas
et al. (2004) identified appearance, milling quality, cooking and processing as well as
nutritional quality as the most important rice grain qualities common to all users. The
nutritional quality of rice is mainly determined by the protein content of the grain.
Tagwireyi and Greiner (1994) reported that 70% of the total protein for human nutrition
in African regions comes from cereals. Studies have shown that protein content of rice is
a quantitative trait (Singh et al., 1977). Breeding efforts for increased protein content in
rice had been largely unsuccessfully owing to low heritability of protein content and
complexity associated with the inheritance of triploid endosperm tissues, and its protein
content has been reported to be negatively correlated with grain yield and some cooking
and eating
criteria (Juliano, 1990).
Brown (1969) identified concentration of useful genes in the same genotypes as
the main objective for self-fertilization of crops. Griffing (1956b), however, had earlier
reported that genotypes vary in their ability to transmit desirable characteristics to their
off-springs. It is on this premise, therefore, that plant breeders try to combine the
desirable qualities of different varieties. The Diallel-cross method introduced by Griffing
(1956a,b) and later modified by Pooni et al. (1984) and Wright (1985) is used in rice
principally to determine the general and specific combining ability of the quantitative
properties (Chan et al., 1990; Hoang and Tan, 1991).
Rice consumption in West Africa has been on the increase compensating for
reduction in consumption of other cereals like millet, sorghum, maize etc. and thus has
19
become an important source of protein (Watanabe, 1998). Similarly, rice quality is a
current preference among rice breeders globally owing to high demand for premium rice
in international markets. On the other hand, malnutrition is currently a serious threat to
the survival of human existence world over, especially in developing countries. Anyanwu
et al. (2009) reported that though staple foods are not considered important sources of
mineral nutrients in the diet, that it is of importance to know that their concentration
might have a significant effect on human nutrition and health. Inspite of this, there is
scanty information on quality traits of most rice varieties grown and consumed in Nigeria.
Information derived from the study will serve to equip Nigerian rice breeders for better
design of rice breeding programmes especially for quality traits of rice. This study used
conventional breeding approaches with Diallel methods to evaluate the nutritional
qualities of some rice genotypes and identify the lines with good spread of protein
contents and agronomic characteristics. This study was therefore designed to achieve the
following objectives:
1. To evaluate 30 genotypes of rice in field experimentation for agronomic
performance, and select eight lines for diallel analysis.
2. Conduct proximate analysis in the laboratory to determine the biochemical
attributes as well as measure the physical grain characteristics of the 28 rice
genotypes that survived the field experiments and select eight lines for diallel
analysis.
3. Perform diallel analysis using the eight selected lines of rice.
4. Estimate the genetic effects of the agronomic and physicochemical characteristics
in the lines generated.
20
Do you need help? Talk to us right now: (+234) 08060082010, 08107932631 (Call/WhatsApp). Email: [email protected].
IF YOU CAN'T FIND YOUR TOPIC, CLICK HERE TO HIRE A WRITER»
