Abstract
Water deficit, more frequently stated as 'drought', is a leading threat to crop
production, especially in rice. It is caused by unpredictable climate change and
severely affects rice growth, development and grain yield. The development of
drought tolerant rice varieties could help farmers reduce the grain yield losses
resulting from the extreme water deficit condition. The present study was
undertaken at the Bangladesh Institute of Nuclear Agriculture (BINA), BAU
campus, Mymensingh to develop high-yielding drought tolerant rice lines
using marker-assisted introgression of drought tolerant loci in the genetic
background of mega varieties Binadhan-11 and Binadhan-17. Previously
reported tightly linked molecular markers for drought tolerance were deployed
to survey tolerant and susceptible genotypes. Among these molecular markers,
eighteen simple sequence repeats (SSRs) markers viz., RM315, RM208, RM262,
RM263, RM279, RM300, RM152, RM277, RM1, RM562, RM71, RM327, RM105,
RM17 RM555, RM324, RM510 and RM234 were polymorphic and applied for
foreground selection in BC₁F1, BC2F1 and BC3F1 generation. From the BC3F2
generation, 25 Near Isogenic Lines (NILs) from Binadhan-11 x NERICA-4 and
23 NILs from Binadhan-17 x NERICA-4 were confirmed with the target
drought-tolerant loci through the graphical genotyping (GGT) software. The
selected lines were screened under the artificial drought conditions at the
reproductive stage following the International Rice Research Institute (IRRI)
standard evaluation system (SES). According to the SES score, eight lines were
tolerant, and twenty lines were moderately tolerant from the Binadhan-11 х
NERICA-4 group. From the Binadhan-17 x NERICA-4 group, eleven lines were
tolerant and thirteen were moderately tolerant. These lines were evaluated for
agronomic performance in the field condition, and finally eight lines viz.
B11/N4-6-2-7-4, B11/N4-6-3-1-2, B11/N4-6-3-3-11, B11/N4-6-3-4-7, B11/N4-18-
9-2-10, B11/N4-21-6-2-15, B11/N4-21-6-5-12 and B11/N4-88-2-2-13 from
Binadhan-11 x NERICA-4 and nine lines viz. B17/N4-25-1-1-9, B17/N4-25-2-2-5,
B17/N4-25-2-6-6, B17/N4-44-1-3-13, B17/N4-44-8-6-15, B17/N4-52-2-4-9,
B17/N4-53-2-4-10, B17/N4-57-1-2-2 and B17/N4-70-1-8-17 from Binadhan-17 x
NERICA-4 were selected as drought-tolerant lines and they showed better
performance in yield compared to their parents and check varieties (one
tolerant and two susceptible). The selected lines could be tested further in the
multi-environment and released as varieties for commercial cultivation,
ensuring sustainable rice production in the drought prone areas of Bangladesh.