The experiment was conducted to evaluate the effect of foliar application of micronutrients for increasing salinity tolerance in rice plants. The results obtained from the study have been presented, discussed and compared in this chapter through table(s) and figures. The analysis of variance of data in respect of all the parameters has been shown in Appendix IV to VIII. The results have been presented and discussed with the help of table and graphs and possible interpretations given under the following headings. The analytical results have been presented in Table 1 through Table 20 and Figure 3 through Figure 29.
4.1 Effect of salinity on growth, yield attributes, yield and harvest index of boro rice
4.1.1 Plant height
Plant height of rice varieties ranged from 46.86 cm to 51.25 cm at 60 DAT, 59.55 cm to 65.56 cm at 90 DAT and 78.69 cm to 91.36 cm at harvest with significant effect of salinity on it (Table 1). At harvest, control treatment showed 16.10%
taller plants than plants which received saline treatment. Islam (2018) reported that salt stress significantly reduced plant height of boro rice. Khanam et al.
(2018) mentioned that plant height was negatively affected by salinity in rice plants. Hossain (2011) recorded that plant height was the highest at control salinity treatment and lowest in the maximum salinity level (12 dS m⁻¹) in rice plants. Sutradhar (2011) observed that the plant height of rice varieties was the highest in 0 dS m⁻¹ level of salinity. Mahmmad et al. (2009) mentioned that on an average, plant height was reduced linearly with increasing soil salinity.
Saleque et al. (2005) concluded that plant height of rice was seriously decreased by salinity level in salt affected soils. Gain et al. (2004) recorded that the height of the plant was decreased gradually with increased levels of salinity, but the effect was insignificant from 7.81 dS m⁻¹ salinity level i.e. below this level plant height was not decreased. Khan et al. (2004) found that plant height, shoot and
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root growth were seriously decreased by salinity. Purnendu et al. (2004) stated that the height of the plant decreased gradually with increased levels of salinity, but the effect was insignificant from 7.81 dS m⁻¹ salinity level. Choi et al. (2003) observed that the plant height of rice decreased in the 0.5% saline water in the soil. Young et al. (2003) showed that height of rice plant decreased at 0.5% saline water in the soil with low salinity level.
Table 1. Effect of salinity on plant height at different DAT of boro rice
Treatments Plant height (cm) at
60 DAT 90 DAT Harvest
S₁ 51.25 a 65.56 a 91.36 a
S₂ 46.86 b 59.55 b 78.69 b
LSD (.05) 4.00 4.82 11.07
CV (%) 5.05 4.65 7.86
[S₁ and S₂ indicate control and 150 mM NaCl, respectively. Mean was calculated from three replicates for each treatment. Values in a column with different letters are significantly different at p ≤ 0.05 applying LSD test]
4.1.2 Number of tillers hill⁻¹
Salinity treatment had significant impact on number of tillers hill⁻¹ at 60 DAT, 90 DAT or at harvest (Table 2). At 60 DAT, tillers number of rice plants ranged from 9.78 to 10.93, at 90 DAT, tillers number ranged from 6.68 to 8.85 while it was 6.27 to 8.80 at harvest. Islam (2018) reported that salt stress significantly reduced number of tillers hill⁻¹ and number of effective tillers hill⁻¹ but increased the number of non-effective tiller hill⁻¹ in boro rice. Khanam et al. (2018) mentioned that tiller number was negatively affected by salinity in rice field.
Hossain (2011) reported that number of effective tillers hill⁻¹ was the highest at control salinity treatment and the lowest in the maximum salinity level (12 dS m⁻¹) for different rice cultivars while number of non-effective tillers hill⁻¹ increased with the increasing level of salinity. Sutradhar (2011) observed that the total tiller number and effective tiller of rice varieties was the highest in 0 dS m⁻¹ level of salinity. Mahmmad et al. (2009) mentioned that on an average, number of tillers per plant was reduced linearly with increasing soil salinity.
Gain et al. (2004) recorded the tiller number of rice plants was decreased
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significantly at 15.62 dS m⁻¹ of salinity level. Purnendu et al. (2004) stated that the tiller number of plants decreased significantly at 15.62 dS m⁻¹ salinity level.
Table 2. Effect of salinity on number of tillers hill⁻¹ at different growth stages of boro rice
Treatments Number of tillers hill⁻¹ (no.) at
60 DAT 90 DAT Harvest
S₁ 10.93 a 8.85 a 8.80 a
S₂ 9.78 b 6.68 b 6.27 b
LSD (.05) 0.26 2.16 2.42
CV (%) 1.55 17.97 18.15
[S₁ and S₂ indicate control and 150 mM NaCl, respectively. Mean was calculated from three replicates for each treatment. Values in a column with different letters are significantly different at p ≤ 0.05 applying LSD test]
4.1.3 Leaf length and leaf breadth
Leaf length of rice plants was significantly influenced by salinity treatment (Table 3). Leaf length ranged from 28.50 cm to 36.07 cm between control and saline treatment. Salinity treatment showed 26.56% shorter leaf than control treatment. Similarly, leaf breadth between control and saline treatment at harvest stage was also significant, which ranged from 1.45 cm to 1.74 cm between the treatments. Khanam et al. (2018) mentioned that leaf number and leaf area were negatively affected by salinity in rice. Khan et al. (2004) found that green leaf area and leaf weight were seriously decreased by salinity where leaf area was decreased more than other growth parameters.
Table 3. Effect of salinity on leaf length and breadth at harvest of boro rice Treatment
combinations
Leaf length at harvest (cm)
Leaf breadth at harvest (cm)
S₁ 36.07 a 1.74 a
S₂ 28.50 b 1.45 b
LSD (.05) 6.50 0.26
CV (%) 12.14 9.96
[S₁ and S₂ indicate control and 150 mM NaCl, respectively. Mean was calculated from three replicates for each treatment. Values in a column with different letters are significantly different at p ≤ 0.05 applying LSD test]
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4.1.4 Filled grains panicle⁻¹ and Unfilled grains panicle⁻¹
Sanity treatment had significant effect on number of filled grains panicle⁻¹ of rice plants (Table 4). Number of filled grains panicle⁻¹ ranged from 52.04 to 77.99 which showed that saline condition reduced 49.86% filled grain in compare to control treatment. The difference between the treatments regarding unfilled grains was also significant. Unfilled grains ranged from 9.48 in control condition to 17.07 in saline condition. Salinity treatment was recorded to produce more unfilled grains (80%) than control treatment. Islam (2018) reported that salt stress significantly reduced number of filled grains panicle⁻¹ but increased the number of unfilled grain panicle⁻¹ of boro rice plants. Hossain (2011) reported that number of filled grains panicle⁻¹ was the highest at control salinity treatment and the lowest in the maximum salinity level (12 dS m⁻¹) for different rice cultivars while unfilled grains panicle⁻¹ increased with the increasing level of salinity. Sutradhar (2011) observed that the filled grain of rice varieties was the highest in 0 dS m⁻¹ level of salinity. Mahmmad et al. (2009) mentioned that on an average, number of grains per panicle was reduced linearly while grain sterility was increased with increasing soil salinity. With increased salinity, reduced number of grains panicle⁻¹ was mainly found responsible for reduction in grain yield. Young et al. (2003) found that percentage of ripened grain dramatically decreased in 0.5% saline water in the soil low salinity level and 0.1% in soil with medium salinity level.
Table 4. Effect of salinity on yield contributing parameters of boro rice Treatments Filled grains
panicle⁻¹ (no.)
Unfilled grains panicle⁻¹
(no.)
Panicle length (cm)
Weight of 1000-grains
(g)
S₁ 77.99 a 9.48 b 25.97 a 21.28 a
S₂ 52.04 b 17.07 a 18.56 b 17.86 b
LSD (.05) 4.64 3.15 6.72 2.56
CV (%) 4.30 14.31 19.06 7.88
[S₁ and S₂ indicate control and 150 mM NaCl, respectively. Mean was calculated from three replicates for each treatment. Values in a column with different letters are significantly different at p ≤ 0.05 applying LSD test]