Legume Genomics and Genetics 2016, Vol.7, No.1, 1-11
2
utilization can help to tackle situation of terminal heat
stress through the development of heat tolerant
cultivars. Earlier, efforts have been made in other
cool-season legume like chickpea to identify the heat
tolerant genotypes under field conditions (Dua, 2001;
Krishnamurthy et al., 2011).
Yet, it is still not clear how heat affects the growth and
development of lentil and whether that can explain
part of the differences in seed yield under heat stress.
Therefore, it is an urgent need to identify the traits that
can be used effectively in field conditions for
screening germplasm and breeding materials at
reproductive stage. Keeping this in view, the present
study aimed (i) to establish an effective screening
technique under the field condition by identifying the
morphological traits related to heat tolerance and yield
and (ii) to validate identified heat tolerant genotypes
using laboratory test.
2 Results
2.1 Genetic variability
The procedure used to screen the heat tolerant
genotypes is presented in Figure 1. In the present
study, out of 334 accessions, 174 accessions flowered
early and matured within 80-85 days after sowing.
These accessions escaped the heat stress and thus were
excluded for further analysis. Another 64 accessions
which did not flower or flowered rarely were
considered as highly sensitive to heat. The remaining
96 accessions whose flowering and podding stage
coincided with high temperature and still flowered
were observed for the number of filled pods/plant,
number of unfilled pods/plant, and number of filled
and unfilled pods on terminal branch of individual
plants. These accessions flowered in 56 to 85 days
(between March 15 and April 30, 2012) when the
maximum day temperature varied between 30.6 and 43
ºC (Figure 2). As a result, development of pods at
maximum day temperature (>35 ºC) was used as a
criterion to classify accessions as tolerant or sensitive
to heat. Thirty seven (37) accessions, which podded
normally and showed pod formation on terminal
branch, were classified as heat tolerant while
remaining 59 accessions that flowered but podded
rarely were classified as sensitive to higher
temperature. The mean, range and standard error of
mean (s.e.m) over two years of these 37 accessions
were calculated, which is presented in Table 1.
Among 37 accessions, number of filled pods/plant
ranged from 3.3 to 51.2 with an average of 23.6 while
unfilled pods ranged from 5.5 to 45.0 with an average
of 24.2. On terminal branch, filled pods were varied
from 1.5 to 10.0 with an average of 3.3 and unfilled
pods were varied from 0.0 to 3.8 with an average of
1.3. The 100-seed weight in these 37 accessions
ranged from 1.1 to 2.5 g with an average of 1.3 g. The
combined analysis of variance over the years indicated
significant genotypic variability for filled and unfilled
pods/plant, filled pods on terminal branch and also for
100-seed weight (100-SW). Heritability estimates
ranged from 8.94 to 58.13% (Table 2). Highest
heritability (58.13%) was observed for filled
pods/plant on terminal branch and it was lowest
(8.94%) for unfilled pods/plant.
Figure 1 Technique used to screen heat tolerant genotype in
lentil under field conditions
Figure 2 Standard weekly temperature over two years during
January to March at experimental farm of IIPR, Kanpur
