ArticlePDF Available

GENETIC IMPROVEMENT AND DEVELOPMENT OF GENETIC STOCKS IN SUGARCANE THROUGH BACKCROSS BREEDING

Authors:

Abstract and Figures

Broadening genetic base through backcross breeding is an effective approach to generate diverse genetic stocks for important economic traits coupled with red rot resistance. Three hundred backcross hybrids developed by backcrossing elite F1 clones (derived by utilizing improved clones (S.officinarum, S. robustum and S. barberi) with improved S. officinarum or improved S. robustum or Co canes showed variability for the traits studied. Heritability estimates varied over the different nobilising generations and study indicated that selection of parents for sucrose % during the nobilisation process will be effective. BC1 and BC2 hybrids developed from improved S. robustum x improved S. officinarum showed an improvement of 16.71% and 34.09%: 22.36% and 40.58% for sucrose % at 360 days in comparison with improved S. officinarum and S. robustum parents, respectively. Crosses with PIR 96-285 and PIR 001188 as one of backcross parents generated high quality recombinants. The introgression of new genes provided backcross progenies with redrot resistance. The prebred clones expressed wide variability for various traits like internode colour, cane thickness, leaf colour, canopy, hairiness, cane yield and quality characters. Among the pre bred materials, 26 clones recorded single cane weight > 1.25 kg, 45 clones with brix % above 20% and 41 clones with juice sucrose above 18.5% and most of them were derived from the crosses involving improved S.officinarum x improved S. robustum parents back crossed to improved S. officinarum or Co canes. Elite trait specific BC1 hybrids viz., 13-69, 13-251, 13-103, 13-208, 13-253, 14-57 and 14-60 and BC2 hybrids viz.,14-42, 14-66, 14-161 combining good quality and yield traits coupled with red rot resistance: 13-57, 13-114, 13-147 and 13-251, 14-76, 14-69, 14-163 and 14-174 with thickness and resistance to red rot can be utilized in sugarcane varietal improvement programmes.
Content may be subject to copyright.
36
RESEARCH ARTICLE
S. Alarmelu, Adhini S. Pazhany and C. Jayabose
ICAR-Sugarcane Breeding Institute, Coimbatore - 641 007, Tamil Nadu, India
*Corresponding author: alarmelu.s@gmail.com
GENETIC IMPROVEMENT AND DEVELOPMENT OF GENETIC STOCKS IN
SUGARCANE THROUGH BACKCROSS BREEDING
S. Alarmelu*, Adhini. S. Pazhany and C. Jayabose
Abstract
Broadening genetic base through backcross breeding is an effective approach to generate diverse genetic
stocks for important economic traits coupled with red rot resistance. Three hundred backcross hybrids
developed by backcrossing elite F1 clones (derived by utilizing improved clones (S.ofcinarum, S. robustum
and S. barberi) with improved S. ofcinarum or improved S. robustum or Co canes showed variability for
the traits studied. Heritability estimates varied over the different nobilising generations and study indicated
that selection of parents for sucrose % during the nobilisation process will be effective. BC1 and BC2 hybrids
developed from improved S. robustum x improved S. ofcinarum showed an improvement of 16.71% and
34.09%: 22.36% and 40.58% for sucrose % at 360 days in comparison with improved S. ofcinarum and
S. robustum parents, respectively. Crosses with PIR 96-285 and PIR 001188 as one of backcross parents
generated high quality recombinants. The introgression of new genes provided backcross progenies with
redrot resistance. The prebred clones expressed wide variability for various traits like internode colour, cane
thickness, leaf colour, canopy, hairiness, cane yield and quality characters. Among the pre bred materials,
26 clones recorded single cane weight > 1.25 kg, 45 clones with brix % above 20% and 41 clones with juice
sucrose above 18.5% and most of them were derived from the crosses involving improved S.ofcinarum x
improved S. robustum parents back crossed to improved S. ofcinarum or Co canes. Elite trait specic BC1
hybrids viz., 13-69, 13-251, 13-103, 13-208, 13-253, 14-57 and 14-60 and BC2 hybrids viz.,14-42, 14-66,
14-161 combining good quality and yield traits coupled with red rot resistance: 13-57, 13-114, 13-147 and
13-251, 14-76, 14-69, 14-163 and 14-174 with thickness and resistance to red rot can be utilized in sugarcane
varietal improvement programmes.
Key words: sugarcane, interspecic hybrid, prebred, genetic stocks
Introduction
Sugarcane breeding has been a success all
over the world by intercrossing few initially
developed interspecic hybrids hence, a very few
Saccharum species clones have been exploited
in the breeding programme. The exploitation
of the unutilized clones of cultivated and wild
species of Saccharum in breeding program was
suggested as early in 1960’s (Berding and Roach,
1987) who indicated that the repeated use of few
parents in hybridization have resulted in narrow
genetic diversity in modern sugarcane cultivars.
In the present scenario, sugarcane cultivars
under cultivation have genetic background
of 20 S. ofcinarum, two S. spontaneum and a
couple of S. barberi and S. sinense clones
which may be a major threat to the
sugarcane productivity and demands concerted
efforts to utilize new genetic diversity (Walker,
1987; Nair, 2012). Wild species is the basic
genetic material available in nature to breeders
for continuous evaluation, characterization and
exploitation in base broadening and for the
development of better varieties. The paradigm
shift in the climate has necessitated the need for
Journal of Sugarcane Research (2018) 8 (1) : 36 - 42
37
continuous supply of potential valuable genes
for crop yield, quality and biotic stresses. Base
broadening (Kennedy, 2001) / Pre-breeding,
aims at creating new base population by gene
introgression that enhance genetic variability in the
germplasm and to identify trait specic potential
donors for direct use in breeding programmes and
avoid genetic vulnerability due to uniformity. It
offers the most important alternative to connect
genetic resources and breeding programmes and
will also assist in identifying heterotic groups
for future programs and trait specic genetic
stocks for genetic enhancement. Eberhart (1971)
suggested that the base population developed
from the rst backcross to adapted germplasm
is the best to start selection. Backcrossing is an
efcient way to transfer characteristics controlled
by one or two genes, although it can be used also
for higher number of genes, including quantitative
characters. The wild species used for introgression
breeding in the present study was improved S.
ofcinarum, improved S. robustum and S. barberi
since it is far more genetically diverse than current
commercial cultivars thereby making it useful for
broadening the genetic base.
Materials and Methods
Elite improved clones of S. ofcinarum and S.
robustum produced through intra population
improvement programme at ICAR-Sugarcane
Breeding Institute (SBI Annual Report, 1991-
1996) and commercial hybrids were utilized in
introgression through backcross breeding. The
breeding material comprised thirty ve back
crosses effected in 2012 involving eight improved
S. ofcinarum (PIO 90-202, PIO 94-345, PIO
00548, PIO 00581, PIO 00760 ,PIO 00764,
PIO 00845 and PIO 001100), ten improved S.
robustum (PIR 89-369, PIR 96-258, PIR 96-
475, PIR 03-107, PIR 001157, PIR 001054, PIR
001058, PIR 001062, PIR 001124 and PIR 00-
1174) and six commercials (Co 775, Co 86011,
Co 94008, Co 09014, CoA 7602 and CoC 671)
as backcross parents. The resulted introgressed
progenies were evaluated in ground nursery
(2013) and clonal trials (2014 - 2015) for HR
brix, Number of millable canes (NMC) and cane
thickness, cane height (cm) at 360 days and
clones with cane thickness (above 2.5 cm), cane
height (> 200 cm) ,NMC ( > 40/6m row) and
HR brix (>19.5%) and juice sucrose % (>18.0
%) were selected. A combined evaluation of 300
selected clones (from two backcross generation
from different groups) was conducted in RBD
of two replications and plot size of 6m x 1R
for yield and quality traits during 2016 and 2017 at
ICAR - Sugarcane Breeding Institute, Coimbatore.
Normal agronomic and cultural practices were
followed to get uniform phenotypic expression
in hybrids. Observations were recorded on three
canes selected randomly in each replication on
agronomic characters such as NMC/row, cane
thickness, cane height, Single cane weight (SCW),
estimated cane yield /row and quality traits viz., brix
% and sucrose % at 300 and 360 days after planting.
Analysis of variance was performed on yield
and yield related traits using standard RBD
analysis. Elite BC1, BC2 hybrids were identied
for each trait based on mean performance over
the parents and genetic improvement in backcross
populations was studied in comparison with base
population.
Results and Discussion
The means for the F1 and two backcross
generations viz., BC1, BC2 generations showed
progressive increase of yield traits and sucrose %
with successive stages of nobilisation. Heritability
estimates varied over the different nobilising
generations and estimates indicated that selection
of parents for sucrose % during the nobilisation
process will be effective. The results indicate that
gain from selection for yield traits like number of
millable canes and single cane weight at the BC1
and BC2 stages was moderate to high.
Journal of Sugarcane Research (2018) 8 (1) : 36 - 42
38
Selection during nobilisation
The prebred clones developed (utilizing improved
S. ofcinarum, improved S. robustum and
commercial Co canes), from three nobilized
generations and different mating groups exhibited
extensive variability for both qualitative and
quantitative traits. They expressed wide variability
for the traits viz., cane population, cane height,
cane diameter, canopy colour, internode shape,
internode color, spines and owering. The means
for the F1, BC1, and BC2 generations showed
progressive increase of yield traits and sucrose %
with successive stages of nobilisation. Heritability
estimates varied from 31.20% - 62.14% over
the different nobilising generations. The results
indicate that gain from selection for yield traits
like number of millable canes and single cane
weight at the BC1 and BC2 stages was moderate to
high. In general, sucrose % have shown moderate
to moderately high heritability and clump yield of
low to moderate heritability.
Genetic progress in the backcross generations
In the improved S. robustum x improved S.
ofcinarum group, the rst generation nobilized
hybrids showed an improvement of 15.12%
for sucrose % at 360 days over the improved
S. ofcinarum parents (Table 1). BC1 hybrids
showed an improvement of 16.71% and 34.09%
for sucrose % at 360 days in comparison with
improved S. ofcinarum and S. robustum parents,
respectively. BC2 hybrids showed an improvement
of 22.36% and 40.58% for sucrose % at 360 days
in comparison with improved S. ofcinarum and
S. robustum parents respectively. Number of
millable canes, cane height and single cane weight
exhibited a substantial improvement compared to
their improved S. robustum S. ofcinarum parents.
BC1 and BC2 exhibited improvement for both
yield and quality parameters suggesting further
exploitation.
The selected hybrids (123) from the improved S.
ofcinarum x improved S. robustum group also
exhibited improvement for both yield and quality
traits. There was an improvement of 23.57% for
sucrose in F1, 30.37% in BC1 and 33.35% in BC2 in
comparison with improved S. ofcinarum parents
(Fig. 1). Similarly an improvement of 41.97%,
49.78% and 53.21% was observed in F1, BC1 and
BC2 respectively in comparison with improved S.
robustum parents. The BC3 hybrids from these two
mating groups also exhibited improvement for
Table 1. Genetic improvement in backcross population of Improved S. robustum x
Improved S. ofcinarum
Improved S. robustum x
S. ofcinarum
Mean performance at 360 days
NMC / row C. ht (cm) SCW (kg) Sucrose % (360 d)
F1 (N = 43) 91.00 270.00 0.99 18.12
% imp over S. o parents 82.00 17.39 -7.48 15.12
% imp over S. r parents 37.88 8.00 16.47 32.26
BC1 (N = 30) 85.00 280.00 1.13 18.37
% imp over S.o parents 70.00 21.74 5.61 16.71
% imp over S.r parents 28.79 12.00 32.94 34.09
BC2 (N = 30) 74.00 300.00 1.34 19.26
% imp over S.o parents 48.00 30.43 25.23 22.36
% imp over S.r parents 12.12 20.00 57.65 40.58
Improved S.ofcinarum parents 50.00 230.00 1.07 15.74
Improved S.robustum parents 66.00 250.00 0.85 13.70
Journal of Sugarcane Research (2018) 8 (1) : 36 - 42
39
yield and quality traits suggesting further studies
on cytogenetical behaviour and breeding potential
in further backcross generations.
Fig.1. Genetic improvement for sucrose % in
backcross population of Improved S.ofcinarum x
Improved S.robustum
Evaluation of introgressed hybrids
Nine families viz., PIR 001157 x PIO 00845, PIO
001057 x PIR 001062, PIR 03-107 x PIO 96-475,
PIO 94-345 x PIR 96-258, PIR03-107 x PIR 96-
475, PIO 001100 x PIR 001174, PIO 001057 x PIR
001100, PIR 96-285 x Co 09014 and PIO 94-345
x PIR 96-258 yielded more selections combining
yield and quality traits and the elite clones from
these families based on synchrony in owering were
subsequently backcrossed with recurrent parent or
commercial canes. Crosses with PIR 96-285 and
PIR 001100 as one of the back cross parents gave
high quality recombinants. The prebred clones
expressed wide variability for various qualitative
traits like internode colour, cane thickness, leaf
colour, canopy and hairiness. Signicant variation
was recorded for cane yield and quality characters
in the prebreeding population. Among the prebred
materials, 26 (F1:6, BC1:11 and BC2:9) clones
recorded single cane weight >1.25 kg, 45 clones
(F1:7, BC1:17, BC2: 21 with brix % above 20%)
and 41 clones (F1:5, BC116: BC2: 20) with juice
sucrose above 18.5% and most of them were
derived from the crosses involving improved
S. ofcinarum x improved S. robustum hybrids
either back crossed to improved S. ofcinarum or
Co canes. The trait-based selection approach in the
hybrid population combined high yield potential,
quality and red rot resistance.
Introgressed hybrids for cane parameters
Nineteen backcross hybrids viz., 13-69, 13-114,
13-253, 14-171, 14-59, 14-179a, 13-36, 13-38,
13-39, 13-44, 13-78, 13-80, 13-125, 13-150,
13-151, 13-198, 13-272, 13-266 and 13-250
were found promising for number of millable
canes in comparison with improved parents
and commercial check Co 86032. The clone 13-
147 recorded the maximum single cane weight
of 1.45 kg and nine clones viz., 13-69, 13-114,
13-253, 14-171, 14-59, 14-179a, 14-57, 14-160,
14-161 were identified with higher single cane
weight than the checks. Five clones viz., 13-57,
13-69, 13-114, 13-147 and 13-251 were thick types
and recorded cane diameter above 2.8 cm. (Table
2). Thirteen other clones viz., 13-36, 13-38, 13-39,
13-44, 13-78, 13-80, 13-125, 13-150, 13-151, 13-
198, 13-272, 13-266 and 13-250 expressed good
eld stand with good NMC, cane height and cane
thickness and were identied as genetic stocks for
further base broadening programmes. Among S.
barberi backcross hybrids 14-60 recorded 2.87
cm and 3.07 cm cane thickness and 1.07 kg and
1.25 kg single cane weight at 300 and 360 days
respectively.
Introgressed hybrids for juice quality (sucrose
%)
Eleven BC1 hybrids viz.,13-57, 13-69, 13-76, 13-
103, 13-114, 13-186, 13-201, 13-208, 13-147,
13-251 and 13-253 (Table 2) recorded juice
sucrose in the range of 18.00 - 20.26% and
performed better than the improved parents and
Co 86032. These elite clones identified for
high sucrose % at 300 and 360 days were
from improved S. officinarum x improved
S. robustum crosses. The clone 13-69 with
Journal of Sugarcane Research (2018) 8 (1) : 36 - 42
40
the highest sucrose of 20.26% at 12 months
of age is from the cross combination of (PIO
03-107 x PIR 96-475) x PIO 03-107. The
BC1 hybrids 13-69, 13-103 and 13-251 showed an
improvement of 4.54, 2.63 and 2.79% for quality:
juice sucrose % at 360 days (Fig. 2) and more
recombinants with high mean brix was obtained
with improved S. ofcinarum as one of the parent
in backcrosses. Among the BC2 clones 14 - 42
recorded the highest sucrose of 22.71% followed
by 14-66 (21.86%), and 14-161 (21.06%) at 360
days in comparison with Co 86032 (19.03%). The
clones, 14-76, 14-69, 14-163 and 14-174 recorded
more NMC and estimated cane yield above 78.53
kg/ row. Two BC1 hybrids viz., 14-57 and 14-
60 (Co 8371 x Pathri (S. barberi)) x Co 0209)
recorded juice sucrose of 18.22 and 18.17%
respectively at 300 days in comparison with Co
86032.
Fig. 2. Elite clones and % improvement for Sucrose
% at 360 days
The pre-bred clones were tested for red rot
through CCT and for natural incidence of smut.
The clones involving PIR 001057, PIR 001058,
PIR 96-285, PIR 001022 as one of the parent in
the back crosses were moderately resistant and
moderately susceptible to red rot. Among the
tested hybrids, 16 were moderately resistant, 10
were resistant to red rot and 24 were moderately
Table 2. Performance of BC1 hybrids
S. No Clone
Brix
(%)
300d
Suc
(%)
300d
SCW
(kg)
Brix
(%) 360d
Suc
(%)
360d
C. dia
(cm)
1 13-57 20.12 18.03 1.08 20.58 18.20 3.04
2 13-69 20.12 18.65 1.38 22.10 20.26 2.80
3 13-76 20.93 18.73 1.00 21.15 19.14 2.50
4 13-103 18.35 16.30 1.04 21.85 19.89 2.50
5 13-114 18.07 15.02 1.28 20.46 18.00 2.89
6 13-186 19.22 17.98 1.06 21.32 19.38 2.50
7 13-201 19.47 17.81 0.81 21.27 19.50 2.11
8 13-208 19.99 18.39 1.21 21.26 19.77 2.71
9 13-147 21.33 19.25 1.45 21.45 19.57 3.04
10 13-251 21.25 19.04 1.15 21.27 19.92 2.81
11 13-253 20.97 18.77 1.20 21.84 19.34 2.72
Co 86032 19.75 18.13 1.18 21.32 19.40 2.80
SE 0.22 0.26 0.03 0.28 0.31 0.04
CD 1.48 1.60 0.28 2.01 2.24 0.39
Journal of Sugarcane Research (2018) 8 (1) : 36 - 42
41
susceptible. The back cross hybrids viz., 14-57
and 14-60 from Co 8371 x S. barberi cross were
MS and MR to red rot respectively.
The elite BC1 hybrids viz., 13-69, 13-251, 13-103,
13-208, 13-253, 14-57 and 14-60 and BC2 hybrids
viz., 14-42, 14-66, 14-161, 14-125 and 14-102
combining good quality and yield traits coupled
with red rot resistance and 13-57, 13-114, 13-147
and 13-251, 14-76, 14-69, 14-163 and 14-174
(Table 3) with thick canes and resistance to red rot
can be utilized as parental donors for further use
in sugarcane varietal improvement programmes.
Table 3. List of trait specic genetic stocks
Trait Genetic stocks
Sucrose %
13-57, 13-69, 13-76, 13-103, 13-114, 13-186, 13-201,
13-208, 13-147, 13-251, 13-253, 14-57, 14-42, 14-66,
14-161, 14-125, 14-102
Cane diameter (cm) 13-251, 14-76, 14-69, 14-60, 14-163 ,14-174
Number of millable canes 14-76, 14-69, 14-163,14-174
Single cane weight (kg) 13-69,13-114,13-253,14-171,14-59,14-179a,14-57, 14-160,14-161,
14-102,14-125
Though introgression of wild germplasm is time
consuming and requires considerable efforts
and resources, it is very important to improve
the commercial breeding populations and pre-
breeding is a promising alternative to link genetic
resources and breeding programs. The products
of base broadening programme have reached
several stages of selection in many countries and
varieties of commercial use from S. spontaneum
have been released for cultivation in Barbados
(Kennedy, 2001). Horsley and Zhou (2014) have
suggested for improvement of BC1 populations
for the coastal hinterland breeding programmes
of South Africa using high sucrose-yielding
parents as sucrose levels progressively increased
in subsequent backcrosses. Jackson et al. (2014)
indicated in his studies that the overall challenge
linked with introgression breeding of basic
germplasm into commercially adapted germplasm
is that the basic germplasm carries along with it
many undesirable traits which need to be selected
through back crossing to the commercially
superior parental material, while at the same
time desirable traits and genes from the wild
donor may be diluted or lost with successive
generations. The variability created through
backcrossing in our study serves as new base
population for further utilization. Introgression
through backcross-breeding strengthens the
breeding pool with genes for desirable economic
characters and resistance to diseases as evidenced
in this study and serves as an efcient source of
genetic diversity. The backcross population of S.
robustum may be an alternate source for quality
and yield traits and superior back cross families
and trait specic stocks for yield, quality and
resistance to red rot and with better adaptability
to the prevailing changing climatic scenario
were identied. Utilization of these clones by
the breeders will help in the development of
trait specic populations to work upon and on
identifying clones with stable resistance to red
rot, smut and tolerance to drought and salinity
stresses. The study suggest further research on
cytogenetical behaviour and genomic-assisted
pre-breeding which will help to overcome the
linkage drag and aid in transfer of useful genes
for sugarcane genetic improvement.
Journal of Sugarcane Research (2018) 8 (1) : 36 - 42
42
Acknowledgements
The authors express gratitude to Dr. Bakshi Ram,
Director, ICAR-Sugarcane Breeding Institute
and Dr. G. Hemaprabha, Head, Division of Crop
Improvement, for providing necessary facilities
to carry out this research work. The authors also
gratefully acknowledge Dr. N. Vijayan Nair
(former-Director, ICAR-Sugarcane Breeding
Institute) for kindly providing the basic genetic
material used in hybridization. Shri P. Periyasamy
and V. Aravindh are kindly acknowledged for data
collection and managing the eld operations.
References
Berding N, Roach BT (1987) Germplasm
collection, maintenance and use. In: Heinz,
D.J. (Eds.) Sugar Cane Improvement
through Breeding. Elsevier Scientic
Publishers, Amsterdam, pp. 143–210.
Eberhart SA (1971) Regional maize diallels
with U.S. and semi-exotic varieties. Crop
Science, 11: 911-914.
Horsley TN, Zhou MM (2014) Potential gains from
introgression breeding based on analysis of
three breeding populations. Proceedings
of the South African Sugar Technologies
Association, 87: 438 - 446
Jackson P, Hale AL, Bonnett G, Lakshamanan P
(2014) Sugarcane. In: Pratap A and Kumar
J, (Eds) Alien Gene Transfer in Crop Plants,
Volume 2. Achievements and Impacts. New
York: Springer. pp. 317-345.
Kennedy AJ (2001) Genetic base-broadening
in the West Indies sugar cane breeding
programme by the incorporation of wild
species. In: Cooper HD, Spillane C and
Hodgkin P (Eds) Broadening the genetic
base of crop production. pp. 283-294.
Nair NV (2012) Sugarcane genetic resources
- status, potential and role in sugarcane
improvement. Journal of Sugarcane
Research, 2(2): 1-8.
Walker DIT (1987) Manipulating the genetic
base of sugarcane. Proceedings of the
Copersucar’s International Sugarcane
Breeding Workshop. Sao Paulo, Brazil. pp.
321–334.
Journal of Sugarcane Research (2018) 8 (1) : 36 - 42
Received: Oct, 2018; Revised & Accepted: Dec, 2018
... These clones are utilized by sugarcane breeders in India to improve commercial varieties. Alarmelu et al. (2018) reported two-backcross hybrids viz.14-57 and 14-60 with S. barberi cytoplasm for further utilization. ...
... Intra-population improved YLD free population improved S. officinarum (PIO) and population improved S. robustum (PIR) clones were identified for use in in the interspecific hybridization (Karuppaiyan et al. 2020). Alarmelu et al. (2018) identified a high sucrose BC derivatives (1-69) from the PIO x PIR cross with sucrose content of 20.26% at 12m. ...
Chapter
Full-text available
This chapter describe inter-specific and inter-generic hybridization in sugarcane. The success and failure of wide hybridization in Saccharum, inter-generic hybrids produced, cytological behavior in inter-generic hybrids etc are also dealt.
Chapter
Sugarcane is an economically important crop, and the impact of climate change can be manifested much more in all stages like germination, tillering, grand growth, and maturity phases. Cane yield and sucrose content are the two principal traits determining commercial cane yield of sugarcane genotypes. Sucrose accumulation in sugarcane stalks is known as ripening, which is influenced by ambient air temperature and sheath moisture index of sugarcane genotypes. Early ripening genotypes are photosynthetically efficient and complete the vegetative developmental phase much faster than the mid-late cultivars by their synchronized tillering phase and low ratio of acid and neutral invertases. Prolonged lower air temperature during the maturity phase before harvest favors sucrose synthesis in sugarcane genotypes due to decreased concentration of acid invertase enzymes in stalks. The average daily temperature of 12–14 °C would be more desirable for proper ripening. However, a drastic decline in temperature below 8 °C during ripening alters the activities of sucrose synthesizing and hydrolyzing enzymes resulting in a sharp decline in sugar recovery. The impact of changing temperature regimes on sucrose accumulation emphasizes future research initiatives to develop improved models that can record the crop physiological processes that will simulate crop response to predicted changes in climate. Modeling approaches predicted that increased sucrose yield could be achieved when the decrease in stalk dry mass is not more than 10%. Impact assessment using CANEGRO model to study the effect of various combinations of temperature and CO2 projected an enhance in fresh stalk biomass and a decrease in sucrose mass by nearly 10–70% (rainfed) and 6–37% (irrigated) in 2040–2060 compared to 1971–2000 across the agro-climatic areas in India. Therefore, detailed studies are required in the future to demonstrate the causes of changes in the behavior of commercial varieties and the effect of climatic variables on the enzyme balance that regulates vegetative growth and ripening.
Article
Thirty-one sugarcane genotypes were planted in the experiment and post-emergence application of Halosulfuron Methyl 75% WG and Metribuzin 70% WP was carried out at the rate of 67.5 g and 1000 g a.i. per hectare on 42 days after planting (DAP). Lower leaves of some of the genotypes were found to show injuries on 5 days after spraying (DAS). Phytotoxicity was recorded in visual scoring scale of 0 to 10 at 7, 15, 21 and 30 DAS. Phytotoxicity rating of the 31 genotypes studied ranged between 0 and 4. Nine genotypes showed no visual injury and found tolerant, while eight genotypes showed moderate toxic effect (rating 4). All the genotypes (14 nos.) that showed phytotoxicity rating of 1 to 3 recovered visually (leaf injuries) except Co 06027 at 30 DAS, while all the genotypes that showed moderate phytotoxicity did not recover completely except Co 94008. The genotypes with Co 7201 and Co 775 as one of the parents showed phytotoxicity rating ranging from 1 to 4. The genotypes, Co 06030, Co 86032, Co 11015, Co 92005 and Co 09004 did not exhibit phytotoxicity symptoms, while their parent, CoC 671 exhibited phytotoxicity. Seven parental genotypes showed 100% probability of no herbicidal injury in their progenies and exhibited herbicidal tolerance from initial stage. Cane yield reduction (> 5%) was observed only in Co 8021, Co 94008 and Co 99006 with herbicide treatment over no herbicide application. The present study provides a preliminary information on the genetic variation among sugarcane genotypes for herbicide tolerance and their parental relationship, which could be utilized for the development of herbicide tolerant varieties for effective weed management in sugarcane agriculture.
Chapter
This book focuses on the previously neglected interface between the conservation of plant genetic resources and their utilization. Only through utilization can the potential value of conserved genetic resources be realized. However, as this book shows, much conserved germplasm has to be subjected to long-term pre-breeding and genetic enhancement before it can be used in plant breeding programmes. The authors explore the rationale and approaches for such pre-breeding efforts as the basis for broadening the genetic base of crop production. Examples from a range of major food crops (pearl millet, maize, potatoes, cassava and Musa ) are presented and issues analysed by leading authorities from around the world. Twenty-seven papers are presented in 4 sections: general principles (7 papers), crop case studies (5 papers), population management (8 papers), and other approaches to broadening the genetic base of crops (7 papers). The book is aimed at plant breeders, genetic resource conservation scientists and research managers in agriculture and biodiversity.
Potential gains from introgression breeding based on analysis of three breeding populations
  • T N Horsley
  • M M Zhou
Horsley TN, Zhou MM (2014) Potential gains from introgression breeding based on analysis of three breeding populations. Proceedings of the South African Sugar Technologies Association, 87: 438 -446
Alien Gene Transfer in Crop Plants
  • P Jackson
  • A L Hale
  • G Bonnett
  • P Lakshamanan
Jackson P, Hale AL, Bonnett G, Lakshamanan P (2014) Sugarcane. In: Pratap A and Kumar J, (Eds) Alien Gene Transfer in Crop Plants, Volume 2. Achievements and Impacts. New York: Springer. pp. 317-345.