Rice Genomics and Genetics 2015, Vol.6, No.1, 1-5
2
population ranged between 1~26.22 g (HKR47 –
7.42 g, MAS26 – 8.34 g). Several studies supported
our results, aerobic rice varieties yielded higher than
lowland varieties under aerobic conditions (Bouman
2002; Xiaoguang et al., 2005; Kato et al., 2009;
Murthy et al., 2011; Babu et al., 2011).
In order to evaluate the association between root and
yield traits phenotypic correlation coefficient was
calculated (Table 2). In the present study, yield per
plant showed a significant positive correlation with
plant height, effective number of tillers per plant,
panicle length and thousand grain weight. Earlier
studies also reported significant association between
yield and plant height, panicle length and number of
tillers (Girish et al., 2006; Nagaraju et al., 2013). It
is necessary to study root morphological character’s
influence on the grain yield and yield morphological
traits. Under water limited conditions, root system
tries to develop adaptability that either may be
beneficiary for the plants or may be tradeoff for
yield. We identified a significant and positive
correlation between yield per plant and root traits;
root length (0.279, p=0.01), fresh root weight (0.232,
p=0.01) and dry root weight (0.269, p=0.01). This
shows that a well developed root system will help
the plant in maintaining high plant water status
which may leads to increase in yield potential under
aerobic conditions. Plant height showed positive
correlation with dry shoot weight (0.305, p=0.01).
Positive association between plant height and shoot
dry weight, maximum root length, root thickness and
root dry weight has been observed by Ekanayake et al.
(1985); and Kanbar and Shashidhar (2004). The
interrelationships between root morphological characters
and yield-related traits clearly showed the role of
root traits in rice plant adaptability under aerobic
conditions.
In the present study, we identified three QTL for
effective number of tillers per plant, one for
thousand grain weight, one for grain yield/plant and
one for root length. A notable aspect of this study
was that all the six QTLwere mapped on chromosome 8
in a region of 24.9 cM segment (36-60.9 cM). QTL
qRL
8.1
with a peak at RM8243 with an R
2
value of
13.7% associated with root length was identified. In
this region
three QTL for root length were reported
by Sandhu et al. (2013) in the mapping populations
MASARB25 × Pusa Basmati 1460 and HKR47 ×
MAS26. QTL qGY
8.1
for grain yield was reported to
be located near to the qRL
8.1
(Sandhu et al., 2013).
Sandhu et al. (2014) reported QTL for root hair
length (qRHL
8.1
at 43.3 cM) in the Aus276/3*IR64
BC
2
F
4
population. Qu et al. (2008) identified two
QTL for root number, one for fresh root weight and
three for root volume on chromosome 8 using a total
of 120 RILs derived from cross between
japonica
upland rice IRAT109 and paddy rice Yuefu. Li et al.
(2005) reported QTL for maximum root length, dry
root weight and ratio of dry root weight to dry shoot
weight using double haploid population from a cross
between two japonica cultivars under three different
conditions (upland, lowland and upland in pvc
pipes). Courtois et al. (2003) identified a QTL for
maximum root length on chromosome 8 using RILs
derived from cross between IAC165 and Co39 rice
varieties. Priyadarshini et al. (2013) evaluated the
effectiveness of the root QTL on grain yield and
water use efficiency in a set of 116 near isogenic
lines (NILs) derived from cross IR64 and Azucena
populations which were screened for grain yield and
water use efficiency under severe reproductive-stage
drought stress. These collocating chromosomal loci
governing different root and grain yield traits may
provide breeders a better prospect to introgress such
regions together as a unit in order to develop high
yielding aerobic adapted cultivars.
QTL qYPP
8.1
, for grain yield per plant at 60.1 cM
with RM72 being the peak marker with an R
2
value
of 20.2% was reported in this study.
Sandhu et al.
(2013) reported QTL for grain yield at 72.2 cM in
the mapping population MASARB25 × Pusa
Basmati 1460. Sandhu et al., (2014) reported QTL
for grain yield adjacent to qYPP
8.1
in the Aus276/3*
IR64 BC
2
F
4
population. Adjacent to qYPP
8.1
,
Vikram et al. (2012) also reported QTL for grain
yield under drought, qDTY
8.1
, in Basmati334/ Swarna.
Hanamaratti et al. (2007) reported QTL on
chromosome 8 associated with relative yield and
drought susceptibility index in IR64 × Binam-derived
NILs under drought stress. Bernier et al.,
(2008)
reported a minor QTL for grain yield at 28 cM
position. Zhang et al. (2006) mapped a QTL related
to drought tolerance on chromosome 8. Sandhu et al.
(2013) reported QTL for effective number of tillers
per plant, adjacent to qTN
8.2
and qTN
8.3
, in the
