yield performance of single / double crosses and f2 progenies in maize

Performance of single/ double crosses and F 2 progenies in maize
469
YIELD PERFORMANCE OF SINGLE / DOUBLE CROSSES
AND F 2 PROGENIES IN MAIZE (ZEA MAYS L.)
Taj Naseeb Khan*, Saifullah Khan Ajmal**, Rashid Saleem**,
and Malik Haq Nawaz*
ABSTRACT
A study was conducted under Maize, Sorghum and Millet Programme at
National Agricultural Research Centre, Islamabad, Pakistan in spring season
2008 to estimate the potential of five commercial single crosses, ten double
crosses, five F 2 progenies and four open pollinated varieties (OPVs) of maize.
Commercial single cross hybrids were selfed to get their F 2 populations and at
the same time these were crossed to get their double crosses. Highly
significant differences were found among these genotypes for days to 50
percent tasselling, days to 50 percent silking, ear height (cm), ear weight per
plot, grain moisture percentage, 100-grain weight and grain yield. Significant
differences were noted for plant height and number of grains per row - . All
genotypes having different genetic make-up showed variable behaviour for the
characters studied. The single crosses, double crosses and even F 2s,
produced more grain yield than open pollinated varieties. The results further
indicated that single crosses proved better in yield than OPVs even in their
second generation i.e. F 2 population.
KEYWORDS: Zea mays; crossbreeding; F 2 progenies; performance; Pakistan.
INTRODUCTION
Maize (Zea mays L.) belongs to family Poaceae and is grown as a
multipurpose crop throughout the world. It is well adaptable to subtropical,
tropical and temperate regions. It possesses a remarkable diversity of
vegetative types having a wide range of ecological adaptation (8, 20). The
unique energy capturing capability and efficient use of CO 2 as C 4 plant have
made it capable of producing maximum grain yield per unit area as compared
to all other cereal crops. Because of its short life cycle and possibility of
growing two crops in a year, maize can play an important role in the economy
of a country. It is the third most important cereal crop after wheat and rice in
*Vegetable Programme, HRI, ** Maize, Sorghum and Millet Programme, CSI, National
Agricultural Research Centre, Park Road, Islamabad, Pakistan.
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Pakistan. It is grown on an area of 0.935 million hectares with an annual
production of 3.262 million tons and average yield of 3488 kg per hectare (1).
Maize is a short duration crop and has a top priority in hilly areas, especially
in northern parts of the country. It is grown in temperate, tropical and subtropical
areas and is used as grain as well as fodder crop. It is also used in
bread making, corn flakes, corn syrup, corn starch and in food and textile
industry (11). Corn oil, an important by-product of maize, is the most suitable
for human consumption due to low level of unsaturated fatty acids (10). The
problem is that quality seed of improved maize genotypes, especially hybrid
maize is not available. Currently, only 28-30 percent of maize area is under
hybrids cultivation. In USA, synthetic varieties grown with high level
production technology were replaced initially by double cross hybrids and
then subsequently by single cross hybrids and now almost 100 percent single
cross hybrids. Therefore, these are giving 6-8 tons per hectare maize grain
yield. In various central American environments, hybrids consistently
outyielded open pollinated varieties (2). About 60-90 percent increase in
maize yield in US corn belt has been attributed to hybrids development (3).
So it is believed that dissemination, adoption and production of hybrid maize
will provide an effective and short term measure for boosting maize
production in Pakistan.
In countries like Pakistan where 65-70 percent area is under poorly
performing land races and varietal mixtures of maize with low use of inputs
and poor technology, the prospects to uplift maize grain yield is two folds.
Maize hybrids are among the first ones, introduced in the country in early
fifties. Efforts were made in this direction and maize breeders produced
several conventional hybrids based on US corn belt inbred lines crossed with
varieties and inbred lines derived from local material. These hybrids had
greater adaptability and high yield potential. However, lack of an appropriate
local seed industry resulted in little diffusion of these genotypes at farm level
and thus emphasis was shifted to develop improved open pollinated varieties
(OPVs). During mid seventies, public-private sectors collaboration introduced
spring maize hybrid technology in Punjab, which ultimately led to the most
successful cultivation of maize in the country – the spring hybrid maize
cultivation. The greater involvement of private sector, especially multinational
seed companies, has turned hybrid maize into a multi-billion industry.
The spring maize production in Pakistan has become the most productive
sector for agricultural production. The development and adoption of maize
hybrids, during both spring and autumn seasons in Pakistan, can lead to a
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Performance of single/ double crosses and F 2 progenies in maize
471
breakthrough for increasing maize productivity on sustainable basis. The
hybrids available in Pakistan are generally marketed by the multinational
companies whereas the improved open pollinated varieties being planted by
farmers come from the public sector organizations. The price of commercial
hybrids is not affordable by the farming community. Therefore, farmers prefer
to cultivate open pollinated varieties. Hybrids generally have higher yield
potential than open pollinated varieties. The use of hybrids is a major source
to maximize per hectare yield in maize. Hybrid maize has long ears, more
grain rows per ear and greater grain yield than open pollinated cultivars (16).
In present study, commercial single cross hybrids, their double cross hybrids
and selfed hybrids (F 2 progenies of commercial hybrids) were compared with
open pollinated varieties to assess their relative performance in terms of
yield.
MATERIALS AND METHODS
Five commercial single cross hybrids were sown under Maize, Sorghum and
Millet Programme at National Agricultural Research Centre, Islamabad,
Pakistan in spring season 2008. At the time of flowering, these hybrids were
crossed to get ten double cross hybrids and selfed to get five F 2 progenies.
The seed from double crosses and F 2 progenies was harvested and sown
again in the autumn season 2008. The seed of all these genotypes alongwith
four open pollinated varieties (Table 1) was sown in RCBD with two
replications. The experimental unit was 5 meter long with plant to plant
distance of 25 cm and row to row distance of 75 cm. Final plant stand was
21 plants per row. NPK fertilizers were applied @ 87-46-50 kg per hectare.
All P and K while 1 / 3 of N were applied during seed bed preparation. The
second dose of N was applied at 50 cm plant height and third dose was given
before tassel emergence. The insecticide i.e. Furadon (granular) was applied
@ 20 kg per hectare after one month of crop emergence to control stem
borers. All other cultural practices were applied uniformly when needed. The
data were collected for biometric plant traits viz. days to 50 percent tasselling,
days to 50 percent silking, plant height, ear height, ear weight per plot, grain
moisture percentage, number of grain rows per ear, number of grains per
row, 100-grain weight and grain yield. The analysis of variance was
conducted according to Steel and Torrie (18) to observe the statistical
significance among all plant characters. Duncan’s multiple range (DMR) test
was applied for comparison between mean values of various plant attributes.
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Table 1.
Maize genotypes (single crosses, double crosses, F 2s and OPVs) included in
the study during 2008.
S.
No
.
Genotypes Status S.
No.
Genotypes
Status
1 6535 Single Cross 13 ZR-123 × MS-259 Double Cross
2 ZR-123 Single Cross 14 ZR-123 × EA-6802 Double Cross
3 EA-6802 Single Cross 15 ZR-123 × Hicorn-8464 Double Cross
4 MS-259 Single Cross 16 EV-3001 OPV
5 Hicorn-8464 Single Cross 17 Agaiti-2002 OPV
6 6535 × ZR-123 Double Cross 18 EV-6089 (Chandni) OPV
7 6535 × EA-6802 Double Cross 19 Sahiwal-2002 OPV
8 6535xHicorn 8464 Double Cross 20 6535 × 6535 F 2
9 6535 × MS-259 Double Cross 21 ZR-123 × ZR-123 F 2
10 EA-6802× MS-259 Double Cross 22 EA-6802 × EA-6802 F 2
11 EA-6802 × Double Cross 23 MS-259 × MS-259 F 2
Hicorn-8464
12 MS-259 × Hicorn-
8464
Double Cross 24 Hicorn-8464 x
Hicorn-8464
F 2
RESULTS AND DISCUSSION
Highly significant differences among genotypes were observed for all
characters studied except for number of grain rows per ear (Table 2). It
indicated the existence of genetic variability for effective future breeding
programme. Significant results for plant height, ear height, ear length, ear
diameter and grain yield agree to the findings of Rafique et al. (12).
Table 2.
Mean square value of some metric traits in maize.
Source of
variation
DF
Days to
50%
tesselling
Days to
50%
silking
Plant
height (cm)
Ear
height
(cm)
Ear weight/plot
(kg)
Replication 1 2.083 2.521 16.45.021 111.203 0.007
Genotypes 23 7.174** 6.847** 445.948* 261.820* 42.911**
Error 23 1.170 1.738 204.89 61.456 0.142
Grain
moisture
(%)
No. of
grain
rows/ear
No. of
grains/row
100-grain
wt.(g)
Grain yield
(t/ha)
1.857 2.083 10.083 0.003 86755.915
10.499** 4.402 ns 36.431* 18.078** 29726204.832**
1.376 2.431 15.736 0.055 58212.255
The data also revealed highly significant differences for most of the traits
(Table 3). Maximum days to 50 percent tasselling were noted in F 2 population
of single cross MS-259 (57.50 days) followed by double crosses ZR-123 ×
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Performance of single/ double crosses and F 2 progenies in maize
473
MS-259 and MS-259 × Hicorn-8464 (55.5 days each). Single cross 6535 and
double cross EA-6802 × Hicorn-8464 took minimum days to tasselling (49.5
days each). All other genotypes showed variable behavior indicating early to
late tasselling between 50 and 55 days. These results are supported by some
earlier workers (6, 9). Maximum days to 50 percent silking were recorded in
F 2 of single cross MS-259 (60 days) followed by single cross Hicorn-8464
and double cross ZR-123 × MS-259 (58.5 days each) (Table 3). Minimum
days (52) were taken by single cross 6535 and double cross EA-6802 ×
Hicorn-8464. All other genotypes took 55 and 58 days for this trait.
Obviously, the genotypes of diversified nature did not show any particular
effect in silking also. The present findings are in accordance with those
reported earlier (4, 7).
The data pertaining to plant height also showed significant differences among
genotypes (Table 3). Maximum plant height (196 cm) was attained by open
pollinated variety Chandni followed by single cross ZR-123 (195.50 cm). The
single cross 6535 showed the lowest height (140.50 cm). Plant height in
other genotypes ranged from 142 to 189 cm. The plant height of single
crosses, double crosses and OPVs was generally greater than F 2 populations
of single crosses EA-6802, Hicorn-8464 and 6535 except the single cross
6535. Similar results have been reported by previous workers (5,6,19).
Open pollinated varieties Chandni and Sahiwal-2002 showed maximum ear
height (92.50 and 92.00 cm), followed by variety EV-3001 (83.50 cm). The
single cross 6535 showed the lowest ear height (45.20 cm). All other
genotypes showed ear height ranging from 54.63 to 77.50 cm except single
cross ZR-123 (80.60 cm) (Table 3). Open pollinated varieties were prominent
in this trait whereas all other genotypes did not show any particular
difference. Similar results have been reported earlier (7, 9, 14, 19).
The single cross MS-259 gave the highest ear weight per plot (20.15 kg)
followed by double cross 6535 × MS-259 (19.67 kg) and single cross 6535
(18.45 kg) (Table 3). The open pollinated varieties Chandni ‘EV-6089’, Agaiti-
2007, EV-3001 and Sahiwal-2002 gave the lowest ear weight per plot i.e.
5.37, 6.09, 7.53 and 10.04 kg, respectively. All other genotypes gave
intermediate performance with 11.24 kg to 18.05 kg ear weight per plot. F 2 s
remained behind the single and double crosses with respect to ear weight but
surpassed open pollinated varieties (13, 17).
Maximum grain moisture percentage was observed in double cross ZR-123 ×
MS-259 (33.60) whereas majority of single crosses and double crosses
showed non-significant difference in this trait (Table 3). Out of 24 genotypes,
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21 showed non-significant differences for grain moisture percentage. Hussain
et al. (6) also reported variation in grain moisture level in maize hybrids. The
lowest grain moisture was noted in variety Agaiti-2002 (23.45%) and EV-
3001 (25.95%). The moisture contents of all other F 2 s were lower than the
single and double crosses (Table 3). These results agree to those of Ihsan et
al. (7) and Rehman et al (13). For grains rows per ear, single crosses MS-
259, 6535, open pollinated variety Sahiwal-2002 and double cross 6535 ×
MS-259 ranked first (17 rows each). All other genotypes had 13 to 16 number
of grain rows per ear (Table 3).
Open pollinated variety EV-3001 topped in number of grains per row (44.0)
followed by single cross ZR-123 (42.0) (Table 3). The lowest number of
grains per row (28.50) was recorded in F 2 of single cross ZR-123. F 2 and few
double crosses had lower number of grains per row. Shahwani et al. (15)
also reported similar results.
Maximum 100-grain weight (28.76 g) was recorded in single cross MS-259
followed by double cross 6535 × MS-259 (27.93 g). The lowest 100-grain
weight was observed in variety EV-6089 (18.67 g) (Table 3). These results
are supported by some earlier scientists (7, 9).
Single cross MS-259 excelled in grain yield (22.19 t/ha) followed by double
cross 6535 × MS-259 and single cross 6535 (15.73 t). The yield of two
double crosses ZR-123 × Hicorn-8464 and EA-6802 × MS-259 was
statistically at par with single crosses 6535 and EA-6802. F 2 progenies of
single crosses ZR-123 and 6535 yielded statistically similar to single cross
and double cross hybrids. Open pollinated variety EV-6089 (Chandni)
yielded the lowest (4.89 t/ha) The F 2 s of single crosses MS-29, Hicorn-8464
and ZR-123 gave more yield than all open pollinated varieties, whereas other
genotypes gave intermediate performance. These results agree to those of
Souza et al. (17).
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