Single Cross Hybrid |
Introduction |
Maize occupies an important place in world
agriculture. It is grown in more than 150 countries. The major producing
countries are
Genotype Development Strategy
vis-a-vis Area, Production, Productivity Scenario of Maize in
Period |
Maize Breeding Strategies |
1950-60 |
Land races |
1960-67 |
Double cross (DC) |
1967-71 |
Composite |
1971-89 |
Composite and Double top cross (DTC) I
DC |
1989-2000 |
Single Cross Hybrid (SCH)/DC / |
2000-06 |
SCH/TWC/DC and
composites |
2006-onwards |
Single Cross Hybrids |
Year |
Area
(m ha) |
Production
(m t) |
Productivity
(kg ha_1) |
2006-07 |
7.89
|
15.10
|
1912
|
2007-08 |
8.12
|
19.77
|
2435
|
Increase (%) |
2.83
|
30.93
|
27.35
|
Figure 1: Trends of area, Production and
productivity of maize in
All
India Coordinated Research Project (AICRP) on maize was launched in 1957 with
the objective to develop and disseminate genetically superior cultivars and crop
production/ protection technologies. Since 1961, a total number of 118 hybrids
have been released under this project. Indian maize programme has now given
focus on single cross hybrids and since 1990, a total number of 42 single cross
hybrids of normal maize, quality protein maize and baby corn have been released
(Annexure-I). During 2007-08, maize production increased by 31 % and
productivity by 27% over the last year (Fig. 1). The spectacular growth in maize
production may be attributed to the development of single cross hybrids which
cover about 20% of the total maize area.
Single cross hybrid maize varieties are the first generations (F1) from
crosses between two inbreds that are genetically dissimilar. Seed production of
single cross hybrid requires only two parents and one season. Seed production
technology is almost similar throughout country except few location specific
technologies. Seed growers may consult local maize breeders of All India
Coordinated Research Project on maize (AICRP on maize) for getting parental
lines of particular single cross hybrid suited for that location. Network of
AICRP centres on maize is given in Map 1.
Map 1. Maize Research Zones and
Centres of the DMR
Region
specific seed
To
meet the increasing demand of quality seed across the country, the seed
production should be region specific a "Seed ViIlage" with program
concept that faciIitates in-
·
overcoming isolation problem
·
with ease in monitoring
·
maintaining genetic purity of the seed
·
reduction in cost of production
·
timely availability of seed
·
reduction in cost of transportation
·
improving farm profitability
·
employment generation to rural masses
·
earning foreign exchange as the cost of single cross
hybrid (SCH) maize seed production is lowest in developing and under developed
world due to low cost of cultivation because of cheaper labour
Prerequisite
of single cross hybrid seed production
·
Proper site selection-avoid the sites where
preceeding crop was maize
·
Fertile and
quality land with good quality and assured irrigation
· Productive, uniform and genetically diverse inbred lines
·
Proper isolation distance
·
Technology (Package of practices) for hybrid seed
production
·
Technically experienced manpower
·
Stress free season
Characteristics
of good seed parent (female)
·
Productive
·
Strong
·
Long cobs with complete exertion (Photo 1)
·
Low cob placement
·
Lax tassel
·
Shorter Anthesis Silking Interval (ASI)
·
Nutrient responsive
·
Stay green trait
·
Erect leaves
·
Resistant/tolerant to biotic and abiotic stresses
·
Strong root system
Photo 1. Long cob with complete exertion
Characteristics
of good pollen parent (male)
·
Lax tassel, long main branch with few
·
Long duration of pollen shedding
· Taller than female parent
·
Attractive grain colour
·
Strong plant resistant to lodging with better root
system
·
High yield potential
·
Resistant/tolerant to biotic and abiotic stresses
Photo 2. Good pollen parent (Male)