Biomedical Engineering Reference
In-Depth Information
difficulties in monitoring the purity of hybrid seed production, and also the resto-
ration frequency is low. ICSSH 58 (ICSA 738
ICSV 93046) is the first A
2
-based
sweet sorghum hybrid in the world bred at ICRISAT and reached the farmers'
fields. Other alternate sources like A
3
,A
4
,A
4M
,A
4VZM
,A
4G1
,A
5
,A
6
, 9E, and KS
are not useful primarily because (1) restorer frequencies are low (restorer fre-
quency: A
1
>
A
3
) and (2) male steriles cannot be readily distinguished
from male fertiles. There is a need to search for more useful form of male sterility
yet different from milo (A
1
). Milo restorers need to be diversified in guinea
background to further enhance the yield advantage in hybrid development. Restorer
frequency is very low on non-milo cytoplasms. So, there is a need to identify and
breed for high-yielding non-milo cytoplasm restorers [
2
,
34
]. The high Brix%
possessing (
A
2
>
A
4
>
14 %) female hybrid parents are not available in plenty on sweet
sorghum breeding programs across the globe to exploit the potential heterosis for
stalk yield and juice yield [
2
].
>
Breeding Sweet Sorghum
Breeding Behavior
Sorghum is basically a self-pollinating crop, but natural cross-pollination varies from
0.6 to 6 % depending on the cultivar. Sorghum has the advantage of possessing
complete self-pollination due to its floral biology, cleistogamy, and genetic
and cytoplasmic genetic male sterility. Breeding methods relevant to self as well as
cross-pollinated crops are, therefore, applied to breed pure line varieties, hybrids, and
populations in sorghum. Hand pollination should begin around 9:30 or 10:00 AM and
can be extended up to 11:30 AM to 12:30 PM on a foggy morning [
22
].
Candidate Traits and Variability
The major characteristics which a sweet sorghum cultivar should possess are:
1. High biomass productivity (75-100 t ha
1
)
2. High Brix% (20-23 %)
3. Thick stems and juicy internodes
4. Photo- and thermo-insensitivity aids to fit into diversified cropping systems
5. Tolerance to shoot pests and diseases
6. Good digestibility of residues when used as forage
7. Tolerance to mid-season and terminal drought
8. Salinity and heat tolerance
9. High water, nitrogen, and radiation use efficiencies
10. Juice quality and quantity sustenance during post-harvesting
11. Grain yield (4.0-7.0 t ha
1
)
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