The field experiment was conducted at net house of the department of agronomy, Sher-e-Bangla Agricultural University during the period from November, 2019 to March, 2020 to evaluate the effect of foliar application of micronutrients for increasing salinity tolerance in rice plants. The experiment consisted of three factors. The factors were: factor A: Salinity level (2):
S₁
= Control (No saline water) andS₂
= 150 mM NaCl; factor B: Micronutrients (4):M₁
= Control (No micronutrients),M₂
= Zinc (0.5%),M₃
= Boron (0.5%) andM₄
= Zinc (0.5%) + Boron (0.5%); factor C: Variety (5):V₁
= BINA dhan10,V₂
= BINA dhan8,V₃
= BRRI dhan29,V₄
= BRRI dhan47 andV₅
= BRRI dhan67. The experiment was laid out in a RCBD factorial design with three (3) replications. Total 120 unit-pots were prepared for the experiment. Each pot was of required size. Data on different growth, yield contributing and yield parameter of rice were recorded and significant variation was recorded for different treatments.It was observed that the control plants
S₁
(No saline water) out-yielded by producing 58.23% higher grain yield overS₂
(150 mM NaCl). The treatmentS₁
(No saline water) also showed the tallest plant at harvest (91.36 cm), highest number of tillers hill−1 (8.80), longest leaf at harvest (36.07 cm), widest leaf at harvest (1.74 cm), longest panicle length (25.97 cm), highest number of filled grains panicle⁻¹ (77.99), lowest number of unfilled grains panicle⁻¹ (9.48), maximum weight of 1000-grains (21.28 g), straw yield (28.75 g hill−1), biological yield (61.52 g hill−1) and harvest index (53.26%) in compare to salinity stress-imposed plants.Significant differences existed among different levels of micronutrient applications with respect to yield and yield attributing parameters. A yield advantages of 5.28 g, 5.31 g and 10.94 g hill−1 over M₁ (No micronutrients), M₃ [B (0.5%)] and M₂ [Zn (0.5%)] applied pot, respectively was found which was
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possibly aided by taller plant (86.24 cm), higher number of tillers hill−1 (7.94), longer panicle (22.21 cm), maximum number of filled grains panicle⁻¹ (67.79), lowest number of unfilled grains panicle⁻¹ (12.19), highest weight of 1000-grains (20.93 g), straw yield (26.07 g hill−1), biological yield (56.31 g hill−1) and harvest index (53.70%) in the M₄ [Zn + B (0.5%)] treatment. On the other hand, treatment M₃[B (0.5%)] gave similar results to M₄treatment in some parameters like—plant height, tillers number, leaf length, number of unfilled grains panicle⁻¹, panicle length, weight of 1000-grains, straw yield, biological yield and harvest index.
The result revealed that V₅ (BRRI dhan67) exhibited its superiority to other tested variety BINA dhan10, BINA dhan8 and BRRI dhan29 in terms of seed yield, the former out-yielded over V₁ (BINA dhan10) by 13.34%, V₂ (BINA dhan8) by 1.27% and V₃ (BRRI dhan29) by 1.20 % higher yield. V₅ (BRRI dhan67) also showed the highest number of filled grains panicle⁻¹ (96.16), lowest number of unfilled grains panicle⁻¹ (7.72), highest weight of 1000-grains (22.20 g), maximum length of panicle (23.02 cm), higher biological yield hill−1 (45.18 g) and the highest harvest index (59.60%) compare to other tested varieties. On the other hand, the variety BRRI dhan29 returned with 37.18% lower grain yield which was significantly lower than BRRI dhan67 variety.
Interaction of salinity level and different micronutrient applications significantly influenced most of the studied parameters including grain yield. The interaction of S₁M₁ was recorded to have the highest grain yield (30.77 g hill−1) than other interactions except S2M4 (28.24 g hill−1) which may be attributed to the highest number of filled grains panicle⁻¹ (77.99), lowest number of unfilled grains panicle⁻¹ (9.48),maximum length of panicle (23.97 cm), maximum weight of 1000-grains (21.28 g) in this interaction. This interaction also showed the highest straw (28.75 g hill−1) and biological yield (59.28 g hill−1). However, interaction of S2M4 showed statistically similar grain yieldand some yield attributes like—
panicle length (22.21 cm), number of filled grains panicle⁻¹ (67.79), number of unfilled grains panicle⁻¹ (12.19) and weight of 1000-grains (20.93 g) to S₁M₁.
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Interaction results of variety and salinity level indicated that most of the studied parameters were influenced significantly including grain yield. Significantly the highest grain yield (32.90 g hill−1) was found in S₁V₂ (No saline water × BINA dhan8) interaction due to the tallest plant (101.38 cm), lowest number of unfilled grains panicle⁻¹ (2.36) and higher weight of 1000-grains (22.67 g) production. It was also observed that S₁V₁ showed the second highest grain yield (31.77 g hill−1).
Interaction of micronutrient applications and variety exhibited significant variation in all the studied parameters in this experiment. The interaction M₄V₃ (Zn + B (0.5%) × BRRI dhan29) performed the best in respect of grain yield hill−1 (30.86 g) which may be attributed to higher length of panicle (23.32 cm) production which also showed the highest straw yield (28.60 g hill−1) and biological yield (59.22 g hill−1) in this interaction.
Interaction effects of salinity level, micronutrient applications and variety showed significant variation for all the studied parameters. Among the interactions, S₁M₁V₂ was superior in producing the highest grain yield (32.90 g hill−1) along with the tallest plant at harvest (101.38 cm), lowest number of unfilled grains panicle⁻¹ (2.36), higher length of panicle (21.51 cm), higher weight of 1000-grains (22.67 g), straw yield (30.86 g hill−1) and the highest biological yield (63.52 g hill−1). S₂M₄V₅, S₂M₃V₁, S₂M₃V₂, S₂M₃V₃ and S₂M₄V₂ interaction showed statistically similar grain yield hill⁻¹ to S₁M₁V₂ interactions.
CONCLUSION
From the above result it was revealed that
S₁
(No saline water), M₄ [Zn + B (0.5%)] and V₅ (BRRI dhan67) gave higher yield along with higher values in most of the yield attributing parameters. Among the interactions; S₁M₁, S₁V₂ and M₄V₃ were superior in most of the studied parameters along with grain yield.116
Interaction of S₁M₁V₂ (No saline water × No micronutrients × BINA dhan8) performed better in most of the studied parameters. The S₁M₁V₂ treatment combination also showed better performance in terms of grain yield. From the result of the experiment, it may be concluded that application of Zinc (0.5%) + Boron (0.5%) combinedly seems promising in mitigating salinity stress in rice field compared to individual application of zinc or boron.