The results on combined effect of silicate sources and growth regulator on plant growth parameters is furnished below.
3.1 Plant height
Application of silicate sources and growth regulator influenced the plant height of maize at three different stages. The height of plant varied from 86.63 to 121.84 cm, 224.67 to 258.33 cm and 226.96 to 271.74 cm / plant at vegetative, tasseling and harvesting stage respectively (Table 1). The maximum plant height of 121.84, 258.33 and 271.74 cm / plant was observed in the treatment with ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) which was statistically on par with ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) which plant height of 119.00 cm, 253.37 cm and 259.23 cm /plant was registered at vegetative, tasseling and harvesting stage respectively (Table 1). Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded plant height of 96.57, 242.33 and 245.06 cm / plant which was on par with 0.2% SA + 50 ppm GA (T11) which plant height of 92.34, 217.67 and 221.43 cm / plant at vegetative, tassel and harvesting stage of maize crop. In the untreated check (T16), the mean plant height recorded was 86.63, 224.67 and 226.96 cm / plant at three different stages of maize crop.
3.2 Stem girth
The stem girth was positively influenced by application of supplemental addition of silicon sources along with growth regulator. The stem girth of maize plant diameter ranged from 3.54 to 5.48 cm, 5.81 to 8.43 cm and 5.92 to 8.85 cm /plant at vegetative, tasseling and harvesting stage respectively (Table 1). Basal application of ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) which was statistically on par with ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) increased stem girth, 5.48, 8.43 and 8.85 cm / plant and 5.41, 8.21 and 8.79 cm / plant was registered at vegetative, tasseling and harvesting stage respectively. Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded stem girth of 4.89, 7.00 and 7.16 cm /plant which was on par with 0.2% SA + 50 ppm GA (T11) which plant stem girth of 4.72, 6.57 and 7.08 cm /plant at vegetative, tassel and harvesting stage of maize crop. In the untreated check (T16), the mean stem girth diameter recorded was 3.54, 5.81 and 5.92 cm / plant at three different stages of maize crop.
3.3 Leaf length and breadth
Application of silicate sources and growth regulator influenced the leaf length and breadth of maize at three different stages. The leaf length of maize plant varied from 29.08 to 49.64 cm, 54.11 to 77.62 cm and 56.08 to 84.37 cm / plant at vegetative, tasseling and harvesting stage respectively (Table 2). Increased leaf length of 49.64 cm, 77.62 cm and 84.37 cm / plant was observed in the treatment with ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) which was statistically on par with ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) and ¼ T2 + 0.4% SA + 100 ppm GA (T6) which plant leaf length of 46.61, 75.30 and 82.14 cm and 43.57, 73.69 and 80.57 cm /plant was registered at vegetative, tasseling and harvesting stage respectively (Table 2). Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded leaf length of 36.81, 62.98 and 68.06 cm / plant which was on par with 0.2% SA + 50 ppm GA (T11) which plant height of 35.02, 62.05 and 67.52 cm / plant at vegetative, tassel and harvesting stage of maize crop. In the untreated check (T16), the mean plant height recorded was 29.08, 54.11 and 56.08 cm / plant at three different stages of maize crop.
The leaf breadth was positively influenced by application of supplemental addition of silicon sources along with growth regulator. The leaf breadth of maize plant ranged from 4.03 to 5.87 cm, 6.86 to 8.73 and 6.91 to 8.96 / plant at vegetative, tasseling and harvesting stage respectively (Table 2). Basal application of ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) which was statistically on par with ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) increased leaf breadth of 5.87, 8.73 and 8.96 cm / plant and 5.64, 8.68 and 8.90 cm / plant was registered at vegetative, tasseling and harvesting stage respectively. Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded leaf breadth of 5.50, 8.18 and 8.65 cm /plant which was on par with 0.2% SA + 50 ppm GA (T11) which plant stem girth of 5.0, 8.12 and 8.61 cm /plant at vegetative, tassel and harvesting stage of maize crop. In the untreated check (T16), the mean leaf breadth diameter recorded was 4.03, 6.86 and 6.91cm / plant at three different stages of maize crop.
3.4 Chlorophyll Index
The data on chlorophyll index showed a fluctuating trend during the crop period. The increased pattern was followed up to the tasseling stage and thereafter declining trend was observed at pre-harvest stage (Table 3). The maximum chlorophyll index was observed at tasseling stage (55.17) followed by vegetative stage (54.32) with basal application of ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4). This was statistically on par with ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) and ¼ T2 + 0.4% SA + 100 ppm GA (T6) which was chlorophyll index of 54.43 and 53.04 respectively during tasseling stage. At harvest stage, the treatment with ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) and ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) which was recorded the chlorophyll index of 45.33 and 42.16 respectively and were at on par statistically. In the untreated check (T16), the least chlorophyll index recorded was 36.87, 36.89 and 28.05 / plant at three different stages of maize crop.
3.5 Cob length
The cob length was positively influenced by application of supplemental addition of silicon sources along with growth regulator (Table 4). The maximum cob length of 25.43 cm was observed in the plant treated with ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) and which was statistically on par with the treatments, ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) and ¼ T2 + 0.4% SA + 100 ppm GA (T6) with cob length of 24.71 cm and 23.25 cm. Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded cob length of 19.46 cm / plant which was on par with 0.2% SA + 50 ppm GA (T11) which plant cob length of 19.21 cm /plant harvesting stage of maize crop. In the untreated check (T16), the mean cob length recorded was 16.85 cm / plant at harvest stages of maize crop.
3.6 Cob girth
Application of silicate sources and growth regulator influenced the cob girth of maize at harvest stage of maize crop. The cob girth of maize plant diameter ranged from 14.07 to 19.03 cm / plant at harvesting stage of maize crop respectively (Table 4). Basal application of ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) which was statistically on par with ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) and ¼ T2 + 0.4% SA + 100 ppm GA (T6) with increased cob girth of 19.03, 17.94 and 17.72 cm / plant was registered at harvest stage respectively. Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded cob girth of 16.47 cm / plant which was on par with 0.2% SA + 50 ppm GA (T11) which plant cob girth of 16.12 cm / plant at harvesting stage of maize crop. In the untreated check (T16), the mean cob girth diameter recorded was 14.07 cm / plant at harvest stage of maize crop.
3.7 Number of grain row cob− 1
Silicon sources and growth regulator application had significant impact on number of grain rows cob− 1 and it ranged from 12.20 to 15.30 (Table 4). The maximum number of grains row cob− 1 of 15.30 was observed in the plant treated with ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) and which was statistically on par with the treatments, ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) and ¼ T2 + 0.4% SA + 100 ppm GA (T6) with number of grain row cob− 1 of 15.20 and 15.00. Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded number of grains row cob− 1 of 14.40 / plant which was on par with 0.2% SA + 50 ppm GA (T11) which plant number of grains row cob-1 of 14.30 / plant of maize crop. In the untreated check (T16), the mean number of grains row cob− 1 was 12.20 / plant of maize crop.
3.8 Number of grains row− 1
Application of silicate sources and growth regulator influenced the number of grains row− 1 ranged from 17.64 to 33.53 (Table 4) and the highest number of grains of 33.53 per row was counted with ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) and which was statistically on par with the treatments, ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) and ¼ T2 + 0.4% SA + 100 ppm GA (T6) with number of grain row− 1 of 31.79 and 29.90. Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded number of grains row− 1 of 22.86 which was on par with 0.2% SA + 50 ppm GA (T11) which plant number of grains row− 1 with 22.10. In the untreated check (T16), the mean number of grains row− 1 recorded was 17.64.
3.9 Number of grains cob− 1
Silicon sources and growth regulator application had significant impact on number of grains / cob and it ranged from 270 to 337 (Table 4). Maximum number of grains cob− 1 of 337 was observed in the plant treated with ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) and which was statistically on par with the treatments, ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) and ¼ T2 + 0.4% SA + 100 ppm GA (T6) with number of grains cob− 1 of 321 and 315. Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded number of grains cob− 1 of 282 which was on par with 0.2% SA + 50 ppm GA (T11) which number of grains cob-1 of 281. In the untreated check (T16), the mean number of grains cob− 1 was 270.
3.10 Test weight (100 gram weight)
Application of silicon sources and growth regulator in various forms slightly enhanced the weight of maize grains which revealed in the test weight (Hundred grain weight). The test weight of cob ranged from 30.41 to 41.84 grams (Table 4) and the highest test weight of 41.84 gram was recorded with ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) and which was statistically on par with the treatments, ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) and ¼ T2 + 0.4% SA + 100 ppm GA (T6) with test weight of 41.80 and 40.87. Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded the test maximum test weight of 34.92 gram which was on par with 0.2% SA + 50 ppm GA (T11) which test weight of 34.21 gram. In the untreated check (T16), the mean test weight of grains was 30.41 gram.
3.11 Grain yield and BC ratio
The maize grain yield recorded was significantly different among various treatments. It was significantly high in the treatment with basal application of 150 kg of calcium silicate / ha + 0.2% SA at 15 and 45 DAS + 50 ppm GA at 30 and 60 DAS (T4)(7,287 kg / ha) followed by 75 kg of calcium silicate + 0.2% SA at 15 and 45 DAS + 50 ppm GA at 30 and 60 DAS (T3)(7, 092 kg/ha) and 75 kg of calcium silicate + 0.4% SA at 15 and 45 DAS + 100 ppm GA at 30 and 60 DAS (T6)(6, 928 kg/ha). The yield recorded in the untreated check was (T16) 4, 104 kg/ha (Table 5). While considering benefit cost ratio, the highest BC ratio was observed in basal application of 75 kg of calcium silicate + 0.2% SA at 15 and 45 DAS + 50 ppm GA at 30 and 60 DAS (T3)(2.54) followed by the treatment with ½ dose of T2 + 0.2% SA at 15 and 45 DAS + 50 ppm GA at 30 and 60 DAS (T4)(2.51)(Table 5).
3.12 Stover yield
Data obtained from stover yield indicated that the enhanced effect of silicate fertilizer and growth regulator on different parts of maize plant was observed. Maximum stover yield of 9.94 t ha− 1 was observed in the plant treated with ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) and which was statistically on par with the treatments, ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) and ¼ T2 + 0.4% SA + 100 ppm GA (T6) with stover yield of 9.91 and 9.80 t ha− 1. Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded highest stover yield of 9.27 t ha− 1 which was on par with 0.2% SA + 50 ppm GA (T11) which stover yield of 9.18 t ha− 1. In the untreated check (T16), the mean stover yield was 5.83 t ha− 1 (Table 5).
3.13 Harvest index (%)
Application of silicon sources and growth regulator in various forms slightly enhanced the harvest index per cent. The per cent of harvest index ranged from 52.83 to 73.31 ha− 1 (Table 5) and the highest harvest index per cent of 73.31 ha− 1 was recorded with ½ dose of T2 (150 kg) + 0.2% SA + 50 ppm GA (T4) and which was statistically on par with the treatments, ½ dose of T1 (75 kg) + 0.2% SA + 50 ppm GA (T3) and ¼ T2 + 0.4% SA + 100 ppm GA (T6) with harvest index per cent of 71.56 and 70.69 ha− 1. Among the foliar sprays, the treatment with 0.4% SA + 100 ppm GA (T12) recorded the maximum harvest index per cent of 65.77 ha− 1 which was on par with 0.2% SA + 50 ppm GA (T11) which harvest index per cent of 64.65 ha− 1. In the untreated check (T16), the mean harvest index per cent was 52.83 ha− 1.