ICRISAT Archival Report 2006 - The seedlings of success in the ...

I. Sorghum
Output target 5C.1: Sorghum germplasm lines/breeding lines with stable and high grain Fe (40−50 ppm) and
Zn (30−40 ppm) contents identified and their character association, and inheritance studied (2009)
Activity 5C.1.1: Screening of germplasm and breeding lines for grain Fe and Zn and evaluating for grain
yield and agronomic traits
Milestone 5C.1.1.1: Five each of germplasm lines/breeding lines with stable and high grain Fe (40−50 ppm) and Zn
(30−40 ppm) contents identified (BVSR/HDU, 2008)
Core collection evaluation for micronutrient density
A large number of germplasm accessions (2974) from the core collection of sorghum were evaluated for accessing
genetic variability for grain Fe and Zn contents. As core germplasm captures most of the variability present in world
collection (>37000) maintained at ICRISAT, the information on the genetic variability would enable identifying
micronutrient-rich lines for use in crossing with agronomically elite lines to generate exploitable variability to
develop micronutrient-dense cultivars and hybrid parents. It would also enable identifying contrasting parents for
effecting crosses to identify transgressive segregants and to develop mapping populations for identifying molecular
markers linked to loci controlling grain Fe and Zn contents.
The core collection along with four control lines known for their Fe and Zn contents were evaluated in an
augmented design at ICRISAT, Patancheru in 2005 postrainy season. For the sake of convenience, the accessions
were evaluated (in contiguous blocks) as three separate groups classified based on days to 50% flowering (early:
≤65 days; medium: 66 to 80 days; late: >80 days). The early group comprising 1095 accessions along with 4 checks
(repeated 11 times); the medium group comprising 1128 accessions along with 4 checks (repeated 12 times); and the
late group comprising 751 accessions along with 4 checks (repeated 8 times). Each accession was sown in one row
of 2 m length. In each accession, the border plants were left for open-pollination and all others were selfed. The data
were collected on days to 50% flowering, plant height, grain yield, 100-grain weight, grain color, plant agronomic
aspect, panicle shape, panicle compactness, glume color, glume coverage, and presence/absence of seed sub-coat.
Grain samples from some of the accessions could not be collected due to severe bird damage. In a few accessions,
the available grains were not sufficient for estimation of Fe and Zn contents. The grain samples harvested from
selfed panicles of 702 accessions of early maturity, 461 accessions of medium maturity, and 238 accessions of late
maturity (making a total of 1401 accessions), and the grain samples harvested from open-pollinated panicles of 118
accessions of early maturity, 69 accessions of medium maturity, and 21 accessions of late maturity (making a total
of 208 accessions) where sufficient quantities were available processed and sent to ICRISAT’s analytical services
laboratory for grain Fe and Zn contents estimation.
A large variability for grain Fe (7.7 ppm to 132.6 ppm) and Zn (15.1 ppm to 91.3 ppm) was observed among the
1401 accessions. The variability observed in core collection is much higher than that reported earlier, based on
screening of 86 genotypes consisting of germplasm lines, hybrid parents of released/marketed hybrids and popular
varieties. Interestingly, white grain accessions used for human consumption in India had on an average 43.6 ppm Fe
and 35.1 ppm Zn which was marginally higher than those with colored grains (40.4 to 42.6 ppm Fe and 30.9 to 34.0
ppm Zn). The average Fe and Zn contents of accessions with testa (42.5 ppm Fe and 34.2 ppm Zn) and without testa
(42.9 ppm Fe and 33.2 ppm Zn) were comparable. However, endosperm texture and grain size have significant
effects on grain Fe and Zn contents. While the accessions with higher than 75% corneous endosperm had 56.2 ppm
Fe and 44.3 ppm Zn contents, those with 0% to 75% corneous endosperm had less than 44.8 ppm Fe and 35.0 ppm
Zn. The texture of endosperm has significance in food preparations. While grains with 50% corneous endosperm are
useful for preparation of ‘roti’ or ‘chapati’ (unleavened bread), the most popular food forms of sorghum grains in
India; and for ‘ingera’ (leavened bread), the most popular food forms of sorghum grains in some parts of Africa,
those with more than 75% corneous endosperm are useful for the preparation of ‘to’ the most popular food form of
sorghum grains in some parts of Africa. Accessions with small grains (with