Germination involves many physio-biochemical changes leading to the activation of embryo. In this present experiment, germination percentage (GP) decreased with stress over control for all the genotypes (Table 1). Among the genotypes, KPG-59, IPC-2013-74 and NDG-15-6 recorded highest GP; and KWR-108, BG-3075 and BG-3076 recorded lowest GP under all the treatments over control, with the highest percentage reduction in T
5. Salt induced inhibition of GP with increasing salinity concentration over control reported in forage cowpea by
Kandil et al., (2017) and in chickpea by
Ashagre et al., (2013) could be attributed to osmotic stress (
Huang and Redmann, 1995). High temperature induced chickpea too resulted in decreased GP (
Naim and Ahmed, 2015). However, it was also evident from these experimental results that the reduction in GP of the better performing genotypes
viz. KPG-59, IPC-2013-74 and NDG-15-6 nearly doubled in T
1 (5.33, 5.41 and 5.33, respectively) from T
3, T
2 (10.67, 12.16, 11.33, respectively) from T
1 and T
4 (21.33, 22.97 and 22.67, respectively) from T
2. In T
5, exhibited percentage reduction ranged from 25.33 to 25.68 by these genotypes might be attributed to plant’s developed cross-tolerance while facing different stresses during early growth.
Shanko et al., (2017) also found significant reduction in GP of chickpea genotypes at lower salinity level, but with increase in salinity level, the rate of reduction in GP was not that much higher than in lower salinity level.
Vigour index (VI) also showed decreasing pattern with stress from control in this study (Table 1). Similar results obtained by Bina and Bostani (2017) in three medicinal plant species under salt stress, might be attributed to reduced water absorption due to lessened osmotic potential (
Ashraf and Harris, 2005). High temperature also recorded poor vigour in black gram
(Piramila et al., 2012). The highest vigour was recorded in the genotype KPG-59 followed by IPC-2013-74 and NDG-15-6, whereas the KWR-108, BG-3075 and BG-3076 were the lowest rankers among genotypes. Again, the genotypes KPG-59, IPC-2013-74 and NDG-15-6 recorded nearly two-fold increase in declining VI when shifted to T
1 (12.67%, 15.38% and 14.62%) from T
3 (5.37%, 5.93% and 6.43% respectively) and T
2 (25.88%, 29.78% and 27.46% respectively) from T
1. The recorded percentage decrease in VI, varying from 34.33 to 36.98 per cent in T
4 and from 42.11 to 43.62 per cent in T
5 by these genotypes might be due to acclimatization of plant to some extent while facing different stresses during early growth.
Seedling dry weight (SDW) is a potent indicator of plant’s performance under stress. In this present experiment, SDW of all the chickpea genotypes decreased under salinity as well as at high temperature stress condition (Table 2). Similar results of gradual decline in SDW were reported by
Singh et al., (2017) in lentil under salinity stress and by
Akasha et al., (2019) in rice seedlings in high temperature stress. However, the genotypes KPG-59, IPC-2013-74 and NDG-15-6 recorded minimum decrease in SDW and the genotypes KWR-108, BG-3075 and BG-3076 recorded maximum decrease in SDW for all the treatments over control. Significant percentage reduction in seedling dry weight of the better performing genotypes
viz. KPG-59, IPC-2013-74 and NDG-15-6 was observed at T
3 (15.79%, 16.74% and 17.64% respectively), T
1 (24.39%, 24.47% and 25.39%) and T
2 (33.19%, 33.69% and 35.06% respectively) over control, but percentage reduction was not as much high as these at T
4 (39.07%, 41.21% and 42.80% respectively) and T
5 (44.94%, 45.45% and 46.89% respectively). The reason behind it may be the cross-tolerance developed in the plant while facing two stresses one after another.
Yield stability index (YSI) is a useful index in selection of tolerant genotypes for its parallel relation with dry matter yield
(Mohammadi et al., 2010). In this present experiment, the highest YSI was obtained by genotype KPG-59 for all the treatments with the average of 0.685, followed by IPC-2013-74 and NDG-15-6 with the respective average of 0.678 and 0.664, whereas the lowest YSI was obtained by genotype KWR-108, followed by BG-3075 and BG-3076 for all the treatments with the average of 0.589, 0.577 and 0.566, respectively (Table 2). Higher value of YSI by the genotype under stress indicates its tolerance
(Singh et al., 2015).
Tolerance index (TOL) increased gradually with stress for all the genotypes (Table 3). However, the genotypes KPG-59, NDG-15-6 and IPC-2013-74 recorded lowest increase of TOL for all the treatments over control, with the maximum value of 24.67, 24.23 and 23.53, respectively at T
5, indicating that these genotypes had a lower dry matter yield reduction under stress condition, whereas the highest TOL value was found in BG-3075, BG-3076 and KWR-108 with the similar pattern, recording its maximum value of 26.78, 27.78 and 27.76 at T
5, indicating these genotypes had a greater dry matter yield reduction in stress condition.
Rosielle and Hamblin (1981) stated that genotypes with lower TOL is associated with more tolerance under stress condition than those with higher TOL. Results by
Kumawat et al., (2017) in lentil support this.