Training Manual Development Of Cultivars And Seed ... - icrisat

Production of Sorghum Hybrids
Belum V S Reddy
Identification of sorghum hybrids for commercial multiplication involves several steps:
• Development and production of A-, B-, and R-lines with high per se performance and GCA. This
has been discussed in the previous chapters.
• Development and testing of experimental hybrids.
• Large-scale multiplication of the selected hybrid parents (A-, B-, and R-lines) for large-scale
production of designated/selected hybrids.
Development and Testing of Experimental Hybrids
Production of A-, B-, and R-lines has been dealt with in the previous chapters. Here we deal with the
production and testing of experimental hybrids.
1. Grow A-lines and R-lines side by side in a crossing block. To get 500 g of hybrid seed, a 6-row
plot of 4 m length should be sown with the required R-line to supply pollen for panicles in the A-
line. The A-line may be sown in 2-3 rows in a 4-m long plot.
2. At anthesis, bag the A-line and R-line panicles after pruning the florets that have protruded
stigmas/anthers.
3. Rogue off-type plants before and during anthesis and avoid using them in crossing.
4. Pollinate panicles in the A-line with bulk pollen from the R-line and bag both A- and R-lines after
pollination.
5. Mark the bags with the following information: date of bagging of both the A-line and the R-line,
date of pollination, and identity of the R-line used in crossing on the panicles of A-line.
6. Harvest the F 1 hybrid seed from the A-line panicles and selfed seed from the R-line panicles
separately, and tag them accordingly. Harvesting should be done on different days to avoid
mechanical mixing.
It is recommended that in case of loss or damage or mutilation of the marked paper bags, the
pollinated male-sterile panicles should be bagged and marked again. So periodic inspection of the
pollinated plots should be undertaken to check for and replace damaged bags.
The experimental hybrids thus produced are evaluated in replicated trials initially at one or two
locations, followed by multilocational testing of selected hybrids from this initial evaluation. Multilocational
testing provides an opportunity to select 1 -3 promising hybrid(s) for large-scale on-farm testing and finally
for release to farmers for commercial cultivation.
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