HETEROSIS AND COMBINING ABILITY STUDIES IN MAIZE (Zea mays L.)

192 Pages·2016·2.27 MB·English

HETEROSIS AND COMBINING ABILITY STUDIES IN MAIZE
(Zea mays L.) WITH EMPHASIS ON TURCICUM LEAF
BLIGHT [Exserohilum turcicum (Pass.) Leonard and
Suggs]

Thesis submitted to the
University of Agricultural Sciences, Dharwad
In partial fulfillment of the requirements for the
Degree of

Master of Science (Agriculture)
in
Genetics and Plant Breeding

By
CHANDANA B. C.

DEPARTMENT OF GENETICS AND PLANT BREEDING
COLLEGE OF AGRICULTURE, DHARWAD
UNIVERSITY OF AGRICULTURAL SCIENCES,
DHARWAD – 580 005

DECEMBER, 2013
ADVISORY COMMITTEE

DHARWAD (S. K. DESHPANDE)
DECEMBER, 2013 CHAIRMAN

Approved by :
Chairman : ___________________________
(S. K. DESHPANDE)

Members : 1. _________________________
(JAYANT SUBRAYA BHAT)

2. _________________________
(J. A. HOSMATH)

3. _________________________
(S. A. ASHTAPUTRE)

4. _________________________
(V. K. DESHPANDE)

5. _________________________
(B. R. PATIL)
C O N T E N T S

Sl. No. Chapter Particulars
CERTIFICATE
ACKNOWLEDGEMENT
LIST OF TABLES
LIST OF FIGURES
LIST OF PLATES
1. INTRODUCTION
2. REVIEW OF LITERATURE
2.1 Combining ability for yield and yield related traits
2.2 Heterosis for various economic traits
2.3 Resistance to turcicum leaf blight
3. MATERIAL AND METHODS
3.1 Geographical location of the experiment
3.2 Weather conditions
3.3 Experimental material
3.4 Experiment 1:
3.5 Recording of observations
3.6 Experiment 2: Screening for resistance to turcicum leaf blight
3.7 Recording of observations
3.8 Experiment 3
3.9 Statistical analysis
3.10 Stability analysis
4. EXPERIMENTAL RESULTS
4.1 Analysis of variance (ANOVA) for yield and its components
4.2 Proportion of contribution of lines, testers and their interaction to total
hybrid variance
4.3 Analysis of variance for combining ability
4.4 General combining ability effects (gca)
4.5 Specific combining ability effects (sca)
4.6 Heterosis over mid parent, better parent and checks
4.7 Studies on disease resistance among parents and hybrids against
turcicum leaf blight in Maize
4.8 Pooled analysis of variance for stability
4.9 Stability analysis
Contd……
Sl. No. Chapter Particulars
5. DISCUSSION
5.1 Analysis of variance (ANOVA) for yield and its components
5.2 Proportion of contribution of lines, testers and their interaction to total
hybrid variances
5.3 Variances and nature of gene action
5.4 General combining ability effects
5.5 Pooled gca status of parents
5.6 Specific combining ability effects
5.7 Pooled sca status of hybrids
5.8 Per se performance and magnitude of heterosis
5.9 Studies on disease resistance among parents and hybrids against
turcicum leaf blight in Maize
5.10 Stability analysis
6. SUMMARY AND CONCLUSIONS
REFERENCES
LIST OF TABLES

Table
Title
No.
1. Character wise summary of review of literature pertaining to
combining ability
2. Character wise summary of review of literature pertaining to heterosis
3. Characteristic features of the genotypes used in the study (Based on
pooled data from 2009-2012 at Dharwad)
4. Disease scoring scale for turcicum leaf blight disease as given by
Payak and Sharma (1983)
5. ANOVA for yield and yield related traits in maize
6. Analysis of variance for parents and hybrids for yield and its
components
7. Proportion of contribution of lines, testers and their interaction to total
hybrid variance
8. Analysis of variance for combining ability
9. Estimates of variance components as reference to the prevailing
gene action for 13 characters
10. Estimates of general combining ability effects of parents for 15 traits
in maize
11. Estimates of specific combining ability effects of experimental single
cross hybrids in respect of traits studied
12. Per se performance and magnitude of heterosis over mid parent,
better parent and standard checks (Arjun, Bioseed-9681 and Super
900M) for days to 50% tasseling
13. Per se performance and magnitude of heterosis over mid parent,
better parent and standard checks (Arjun, Bioseed-9681 and Super
900M) for days to 50% silking
14. Per se performance and magnitude of heterosis over mid parent,
better parent and standard checks (Arjun, Bioseed-9681 and Super
900M) for plant height (cm)
15. Per se performance and magnitude of heterosis over mid parent,
better parent and standard checks (Arjun, Bioseed-9681 and Super
900M) for plant girth (cm)
16. Per se performance and magnitude of heterosis over mid parent,
better parent and standard checks (Arjun, Bioseed-9681 and Super
900M) for ear height (cm)
17. Per se performance and magnitude of heterosis over mid parent,
better parent and standard checks (Arjun, Bioseed-9681 and Super
900M) for ear weight (g)
18. Per se performance and magnitude of heterosis over mid parent,
better parent and standard checks (Arjun, Bioseed-9681 and Super
900M) for ear length (cm)

Contd….
Table
Title
No.
19. Per se performance and magnitude of heterosis over mid parent, better
parent and standard checks (Arjun, Bioseed-9681 and Super 900M) for
ear diameter (cm)
20. Per se performance and magnitude of heterosis over mid parent, better
parent and standard checks (Arjun, Bioseed-9681 and Super 900M) for
Number of rows per ear head
21. Per se performance and magnitude of heterosis over mid parent, better
parent and standard checks (Arjun, Bioseed-9681 and Super 900M) for
number of seeds per row
22. Per se performance and magnitude of heterosis over mid parent, better
parent and standard checks (Arjun, Bioseed-9681 and Super 900M) for
100-seed weight (g)
23. Per se performance and magnitude of heterosis over mid parent, better
parent and standard checks (Arjun, Bioseed-9681 and Super 900M) for
shelling percentage
24. Per se performance and magnitude of heterosis over mid parent, better
parent and standard checks (Arjun, Bioseed-9681 and Super 900M) for
grain yield per plant (g)
25. Per se performance and magnitude of heterosis over mid parent, better
parent and standard checks (Arjun, Bioseed-9681 and Super 900M) for
fodder yield per plant (g)
26. Per se performance and magnitude of heterosis over mid parent, better
parent and standard checks (Arjun, Bioseed-9681 and Super 900M) for
protein content (%)
27. Range of heterosis over mid parent, better parent and checks for yield
and componental traits in maize
28. Screening of maize experimental hybrids against turcicum leaf blight of
maize caused by Exserohilum turcicum (Pass.) Leonard and Suggs
29. Per cent disease index for experimental hybrids against turcicum leaf
blight of maize
30. Reaction of maize hybrids against turcicum leaf blight under field
condition
31. Pooled ANOVA for stability of yield per se in Maize
32. Stability parameters for yield per se in Maize hybrids
33. Simple pooled gca score for yield and important yield attributing traits
34. Per cent gca method for yield and important yield attributing traits
35. Weighted gca method for yield and important yield attributing traits
36. Simple pooled sca score for yield and important yield attributing traits
37. Per cent sca method for yield and important yield attributing traits
38. Weighted sca method for yield and important yield attributing traits
39. Top crosses exhibiting desirable per se performance with respect to
fifteen traits in maize
40. Promising top five hybrids for grain yield per plot (q/ha)
41. Disease reaction of 72 hybrids in line × tester design
42. Promising top hybrids under artificial disease epiphytotic conditions for
turcicum leaf blight
43. Promising hybrids for enhanced disease resistance and yield per se
LIST OF FIGURES

Figure
Title
No.
1. gca effects of parents for grain yield per plant
2. Weighted gca effects of parents for grain yield per plant
3. Pooled weighted gca effects of parents for grain yield per plant
4. sca effects of five superior crosses for grain yield per plant
5. Weighted sca effects of five superior crosses for grain yield per
plant
6. Pooled weighted sca effects of five superior crosses for grain yield
per plant
7. Heterosis over three checks for days to 50 per cent tasseling
8. Heterosis over three checks for days to 50 per cent silking
9. Heterosis over three checks for ear weight (g)
10. Heterosis over three checks for grain yield per plant

LIST OF PLATES

Plate
Title
No.
1 Superior hybrids with highest yield per se
2. Resistant and susceptible checks used for disease screening
3. Superior hybrids with enhanced disease resistance and yield per
se with their disease reaction
INTRODUCTION

Maize (Zea mays L.; 2n = 20) is a new world coarse cereal belonging to the family Gramineae
and tribe Maydeae. Maize is adapted to diverse environments due to its range of plasticity, which is
unmatched by any other crop. Hence, the expansion of maize to new areas and environment still
continues. Though it is a tropical crop by origin, it has adapted magnificently to temperate
environments with much higher productivity. It is grown from latitude 580 N to 400 S, from sea level to
higher than 3000 m altitude and in areas receiving yearly rainfall of 250 to 5000 mm (Downsell et al.,
1996). However, most of the area under this crop is in the warmer parts of temperate regions and in
humid subtropical climate. Highest production is in area having the warmest month isotherms from
210C to 270C and a frost free season of 120 to 180 days.
Maize is the world’s third most important cereal crop after wheat and rice. Maize is used both
as food and feed. Maize is known as “queen of cereals” due to its highest genetic yield potential
among the cereals. It stands first with respect to productivity among the cereals followed by rice and
wheat. It gives highest average grain yield (5.11 t ha-1) as compared to major cereals such as wheat
(2.5 t ha-1) and rice (3.7 t ha-1) because of efficient utilization of radiant energy and fixations of carbon
dioxide from the atmosphere. It has the highest potential of per day carbohydrate productivity. Thus,
the father of green revolution, the renowned Noble Laureate, Dr. Norman E. Borlaug, believes that
“after the last two decades saw the revolution in rice and wheat, the next few decades will be known
as maize era”. It is cultivated on nearly 161.02 m ha in about 160 countries having wider diversity of
soil, climate, biodiversity and management practices that contributes 36% (822.7 m t) in the global
grain production.
The United States of America (USA) is the largest producer of maize followed by China. The
USA has the highest productivity (> 9.6 t ha-1) which is double than the global average (4.92 t ha-1).
India ranks tenth in production and occupies fifth place in area under maize in the world. In India, it is
the third most important food crops after rice and wheat. In India, it is grown over an area of 8.78 m
ha with a production of 21.79 m t with an average productivity of 2.47 t ha-1.
In India, maize is grown both in kharif and rabi seasons with a share of 85 per cent and 15 per
cent, respectively. The maize is cultivated throughout the year for various purposes including grain,
fodder, green cobs, sweet corn, baby corn, pop corn. The predominant maize growing states that
contributes more than 80% of the total maize production are Andhra Pradesh (20.9%), Karnataka
(16.5%), Rajasthan (9.9%), Maharashtra (9.1%), Bihar (8.9%), Uttar Pradesh (6.1%), Madhya
Pradesh (5.7%), Himachal Pradesh (4.4%). Besides, maize is also grown in Jammu and Kashmir and
North-Eastern states. Maize has emerged as an important crop in the non-traditional regions as well.
For instance, in peninsular India the state like Andhra Pradesh ranks 5th in area (0.79 m ha) and has
recorded the highest production (4.14 m t) and productivity (5.26 t ha-1) in the country.
In Karnataka, maize is cultivated over an area of 1.14 m ha with a production of 4.01 m t and
an average productivity of 3.7 t ha-1. In Dharwad district, maize covers an area of about 0.04 m ha
with a production of 0.13 m t and an average productivity of 3.1 t ha-1 (Anonymous, 2012). Area under
maize is increasing rapidly in the state, because of better environment and possibility of cultivation in
all three seasons. Thus, there is a greater scope to improve maize productivity further in this state.
Maize in India, contributes nearly 9% in the national food basket and more than Rs. 100
billion to the agricultural GDP at current prices. In addition, it is generating employment to over 100
million man-days at the farm and downstream agricultural and industrial sectors. In addition to staple
food for human being and quality feed for animals, maize serves as a basic raw material or as an
ingredient to thousands of industrial products that includes starch, oil, protein, alcoholic beverages,
food sweeteners, pharmaceuticals, cosmetics, films, textiles, gums, package and paper industries etc.
Nutritionally maize kernel contains 60 to 68 per cent starch, 2 per cent sugar, 7 to 15 per cent
protein, 2 per cent ash on a water-free basis, 5 per cent pentosan and 5 per cent oil. The embryo
which forms about 12% of the whole grain is the source of protein, fats and sugars. Yellow maize is
the richest sources of Vitamin-A. Maize has more riboflavin than wheat or rice and is rich in
phosphorous and potash. Maize oil is also low in linolenic acid (0.7%) and contains a high level of
natural flavour.
With the introduction of high yielding hybrids, there has been a phenomenal increase in the
area and production, but at the same time, it is prone to several foliar diseases (Payak and Sharma,
1980). Maize is affected by more than 60 diseases. Based on the research efforts for the last few
years under the aegis of All India Coordinated Maize Improvement Project, 16 out of 61 diseases
adversely affecting this crop have been identified as major ones (Payak and Sharma, 1982). Among
the foliar diseases affecting maize, the turcicum leaf blight (TLB) also called as Northern leaf blight
caused by Exserohilum turcicum (Pass.) Leonard and Suggs (syn. Heliminthosporium turcicum Pass.)
is of worldwide importance (Carlos, 1997). More than 50 per cent loss in grain yield was reported in
USA (Robert, 1953; Raymundo and Hooker, 1981).
In India, TLB disease is distributed in all maize growing states. The endemic areas (hot spots)
of the disease are, Arabhavi and Nagenahalli in Karnataka, Kolhapur in Maharashtra, Karimanagar in
Andhra Pradesh, Dholi in Bihar and Almora in Uttaranchal (Laxminarayan and Shankarlingam, 1983).
The disease epidemics at an early stage causes premature death of blighted leaves, which lose their
value as fodder (Payak and Renfro, 1968). Severe losses in grain yield due to epiphytotics have been
reported in several parts of India and these losses vary from 25 to 90 per cent depending upon the
severity of the disease (Chenulu and Hora, 1962; Jha, 1993).
In Karnataka, turcicum leaf blight is prevalent in almost all the maize growing areas and
ubiquitous incidence of turcicum leaf blight in the pre-harvest stage is prominent. The disease is
responsible for premature death of blighted leaves and results in significant yield reductions. It is
considered to be one of the most devastating disease as it appears in sizeable form in Karnataka
resulting in grain yield loss of 28 to 91 per cent (Pandurangegowda, 1991; Kachapur, 1988; Harlapur
et al., 2000; Patil et al., 2000). Thus, the disease has attained economic status in the state.
Though, the TLB disease can be managed by chemicals and crop husbandry practices, the
most appropriate and economical strategy is through exploitation of host plant resistance, which is not
only environmentally friendly but also convenient to adopt at farmer’s level. Thus, identifying resistant
genes and genotypes to this important disease and combining them with yield traits is a priority of
Indian maize breeding programmes (Sharma et al., 2005).
The invention of heterosis phenomenon (Shull, 1908), the development of hybrid breeding
technology and exploitation of heterosis in maize are the land marks in the biological sciences during
the present century. Plant breeders have created a homozygous (inbred) state a naturally outcrossing
maize crop. This may help explain why maize exhibits relatively high heterosis when compared to
other species. A number of cultivar e.g., single crosses, double crosses, varietal hybrids, multiple
hybrids, composites, synthetics, pools, populations etc., are available to maize growing farmers for
commercial cultivation by virtue of the crop being a highly cross pollinated. It is estimated that the use
of hybrids and heterosis increases yields nearly 15% per annum in maize (Duvick 1999). The study of
heterosis can provide the basis for the exploitation of valuable hybrid combinations in the breeding
program.
Development of the hybrids is important to increase yield per se and enhance resistance for
important diseases. In any hybrid breeding programme choosing of the appropriate parents is
important to realise significant heterosis for economic traits. So, selection is done based on per se
performance, genetic diversity and combining ability of the parents.
The genetic architecture of yield can be better understood through the application of
biometrical principles. Several biometrical methods give information on the combining ability status of
parental lines. One of the techniques widely used is Line x Tester (L × T) analysis developed by
Kempthorne (1957). This analysis provides reliable information on magnitude of additive and non-
additive components based on the general and specific combining ability effects of parents and their
hybrid combinations.
Combining ability studies provide information on the relative importance of GCA and SCA
variance for interpreting the genetic basis of important traits. This helps us to assess the nature of
gene action and in identifying superior parental lines for their per se performance. The best
combinations with high general combining ability of individual lines are helpful to get more desirable
recombinants which enables for further improvement of the crop.
Keeping in view of the above information, the present study was carried out by crossing 12
lines with 6 testers with varying degree of resistance to turcicum leaf blight to obtain 72 single cross
hybrids. The resultant hybrids along with the parents were evaluated under field conditions with the
following objectives.
1. To study the combining ability for yield and yield related traits in selected inbred lines.
2. To study the extent of heterosis for various economic traits in the single cross hybrids.
3. To screen the parental lines and resultant hybrids for resistance to turcicum leaf blight.
REVIEW OF LITERATURE
Maize is a highly cross pollinated crop and hand emasculation (detasseling) and wind borne
pollination is used to produce hybrid seeds on a commercial scale. The scope for the exploitation of
hybrid vigour will depend on the direction and magnitude of heterosis, biological feasibility and the
type of gene action involved. Exploitation of hybrid vigour in maize has gained much significance in
view of its tremendous yield increase. There is a continuous need to evolve new hybrids, where
quality and enhanced tolerance to foliar disease like turcicum leaf blight should exceed the existing
hybrids yield per se. In recent time, more emphasis has been placed for the development of superior
single cross hybrids.
In order to focus on the further improvement of the crop, literature pertaining to heterosis,
combining ability and turcicum leaf blight disease resistance is reviewed and presented under the
following heads.
2.1 Combining ability for yield and yield related traits
2.2 Heterosis for various economic traits
2.3 Resistance to turcicum leaf blight
2.1 Combining ability for yield and yield related traits
Evaluation of crosses among inbred lines is an important step towards the development of
hybrid maize (Hallauer, 1990). Maize breeding programs designed for specific-end uses, improved
maize genotypes, tolerant to pests/diseases and development of commercial maize hybrids usually
require good knowledge of combining ability of the breeding materials to be used. Combining ability
analysis is usually employed to understand the nature of gene action of different yield contributing
characters and to identify desirable parents in order to exploit heterosis. Combining ability studies
provides sufficient inferences for selecting suitable inbred parents and their specific combinations and
also used to assign germplasm into heterotic groups.
The concept of GCA and SCA were given by Sprague and Tatum (1942). General combining
ability (GCA) is an average performance of an individual in a particular series of crosses, while
specific combining ability (SCA) is a performance of a parent x in a cross to a parent Y, where the
average value of this combination can deviate from the average value of general combining abilities of
these parents in comparison to some other parents (Borojević, 1981).The breeding value expressed
as deviation from the population is nothing but the gca effects of a particular genotype. Griffing (1956)
has shown relationship between various heritable variance components and GCA and SCA
variances. The sca effects and SCA variances take into account the performance of the specific cross
combination which indicates the value of inbred lines in hybrid combinations.
Hayes and Immer (1942), Tandon et al. (1970) opinioned that combining ability is an
important criterion to select inbred lines as parents, in addition to selection for other characters that
are desired. They also emphasized that combining ability is as important as genetic diversity of
parentage for heterotic performance of hybrids. It provides information on the relative importance of
general combining ability (GCA) and specific combining ability (SCA) for interpreting the genetic basis
of important traits.
A high yielding line may not necessarily be able to transmit its superiority to the hybrids,
hence, an estimate of gca (worth of parents) and sca (worth of hybrids) effects may be more reliable
test rather than per se performance (Allard, 1960). The ratio of these variances indicates the nature of
gene action governing the traits, which is important to decide upon the breeding methods to be
adopted, for improvement in the crop using superior genotypes and for eventual success. So in order
to fulfil the objective, the information has been compiled character wise and reviewed below.
2.1.1 Days to 50 per cent silking
Equal importance of both GCA and SCA variance was emphasized by several workers
(Hassaballa et al., 1980; Khehra et al., 1980; Lee et al., 1986; Dahlan et al., 1997; Arun Kumar, 2001;
Desai and Singh, 2001; Alamnie et al., 2003 and Premlatha et al., 2011). But combining ability studies
by Dhillon and Singh (1976), Vasal et al. (1992), El-Hosary et al. (1994b), El-Moula et al. (2004),
Altinbos (1995) clearly indicated the predominant role of only GCA variance. Contrarily Sedhom
(1994), Singh and Singh (1998) observed predominance of SCA variance in the inheritance of days to
50 per cent silking.