A glass house study evaluated 14 brown midrib (bmr) sorghum genotypes for drought tolerance. The study found that genotype N 593 had the highest transpiration efficiency under drought conditions, meaning it was most efficient at using water during drought. Several genotypes were identified as having low lignin content, high biomass, and higher water holding capacity, making them promising as feedstocks for second generation biofuel production. Further testing is still needed in target environments.

1. Feb 2017
Determining transpiration efficiency of bmr sorghum genotypes
for progressive drought tolerance
Romana K Kirandeep1
, Kunapareddy Anil1
, Gupta Rajeev1
, Are Ashok Kumar1
*
1
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad, India
About ICRISAT: www.icrisat.org
ICRISAT’s scientific information: http://EXPLOREit.icrisat.org
E-mail: A.AshokKumar@cgiar.org
Introduction
• Sorghum (Sorghum bicolor (L) Moench) has been considered as a
multipurpose crop serving the needs of developing countries such as
food, feed, fodder and as feedstock for biofuel production
• Brown midrib mutants (bmr) sorghum with reduced lignin content
can be used as feedstocks in 2G biofuel production.
Methodology
A glass house experiment with 14 bmr genotypes in CRD with 10
replications was conducted in complete randomized design (CRD) to
screen the mid-season drought tolerance.
• Stress was imposed by withholding water from 28th
day after
germination to 60th
day after germination by sealing the pots with
plastic sheets and beads.
• Two sets of plants were maintained as well watered (controls) and
water stressed.
• Before imposing the stress, one plant from each pot was harvested
for pre dry down biomass.
• After the stress period, the plants were harvested and the most
tolerant lines were identified based on their response to various
physiological parameters.
Results
• N 593 had the highest transpiration efficiency in water-stressed
condi­tions, whereas N 592 had the highest in well-watered
condi­tions
• The lowest transpiration efficiency was observed in N 597 under
water stressed treatment. However, for well watered treatments the
lowest was observed in N 596 (Table & Fig.)
References
Matthews, RB, Reddy, DM, Rani, AU, Azam-Ali, SN and Peacock, JM.
(1990). Response of four sorghum lines to mid-season drought. I.
Growth, water use and yield. Field Crops Res. 25, 279–296.
Kholová J, Hash CT, Kakkera A, Kočová M and Vadez V. (2010)
Constitutive water-conserving mechanisms are correlated with the
terminal drought tolerance of pearl millet [Pennisetum glaucum (L.) R.
Br.] Journal of Experimental Botany. 61:369–377.
Vadez V, Deshpande SP, Kholova J, Hammer GL, Borrell AK, Talwar
HS and Hash CT. (2011). Stay–green quantitative trait loci's effects on
water extraction, transpiration efficiency and seed yield depend on
recipient parent background. Funct. Plant Biol. 38, 553–566.
Table: Means of various parameters for Progressive Drought Stress
in bmr sorghum
S. No
Traits
Plant height
(cm)
Fresh
Biomass
(S+L) (g) SPAD
Dry Biomass
(S+L) (g)
Specific leaf
area (cm2/g)
TE
(g/kg)
WW WS WW WS WW WS WW WS WW WS WW WS
Atlas (NSL 3986) 76.6 80.9 65.1 82.9 35 37.6 21 20.1 208.7 308 4.4 8.2
Atlas bmr-12 87.9 70.5 78.1 82.7 34.8 37.8 27.4 14.7 187 417 8.1 8.2
Early hegari sart 78.7 65.6 74.5 86.9 35.2 33.3 30.8 18.6 254.4 322 5.7 6.8
IS 18542 64.5 58.9 61.7 91.7 35.7 31.6 26.1 15.6 181 200.4 6.5 8.6
Kanas collier 79.6 67.8 85.7 89.1 36.4 34.1 28.6 17.2 143.5 355.4 4.3 9.7
N 592 81.9 67.4 72.9 109.3 35.5 33.2 29.3 14.8 236.3 287.2 9.3 8.6
N 593 62.3 84.1 48.9 89.3 31.2 32.5 25.1 9.5 302.6 242.1 10 8.4
N 594 90.4 83.3 88.1 82.9 34.2 38 30.1 16.5 239 286.4 2.9 8.9
N 595 63.3 78.7 82.1 70.9 27.9 32.1 31.3 12.6 172.3 169.5 9.5 5.6
N 596 71.7 70.5 70.3 79.5 33.1 29.2 30 14.4 275.4 195.5 11.5 8.3
N 597 84 86.8 46.9 71.8 38.1 40.4 13.1 15.4 176.6 172.5 7.5 8.1
N 598 102.9 91.2 49.3 82.7 33.7 35.9 20.4 9.9 312.9 144.5 2.7 6.2
R-16 (Check) 55.1 68.9 70.1 83.9 27 29.6 34.6 10.6 248.9 272.7 4.9 6.4
Rox orrange 77.1 73.2 87.9 90.7 31.3 33.4 31.8 11.7 150 133.5 5.7 5.3
Mean 76.9 74.8 70.1 85.3 33.5 34.2 27.1 14.4 220.6 250.5 6.6 7.7
Abstract
Food and energy security are fundamental to the economic de­velopment of nations and considering environmental issues, bi­omass-based energy
is a promising option in India through lin­go-cellulosic (2G) biofuel production. High biomass sorghum is a promising feedstock for 2G biofuels
production. However, higher lignin content of the biomass and water-deficit stress are major issues in enhancing biomass sorghum based biofuels
production. In sorghum, brown midrib (bmr) mutants with re­duced lignin content were developed. A glass house study on 14 bmr sorghum helped
to identify genotypes with more wa­ter-holding capacity to adapt well in drought conditions. The bmr genotypes used here showed reduced lignin
content vis-à-vis white midrib sorghums. Thus, the identified lines with low-lignin, high biomass and higher water holding capacity can be used as
feedstocks in 2G Biofuels production after appropriate testing in target environments.
Fig: Transpiration efficiency in bmr sorghum lines.
Conclusion
The bmr genotypes showed reduced lignin content vis-à-vis white
midrib sorghums. Thus, the identified lines with low-lignin, high
biomass and higher water holding capacity can be used as feedstocks
in 2G Biofuels production after appropriate testing in target
environments.