Usha, C ThomasNavya, M VKAU2024-11-112024-11-112021-12-23175257https://krishikosh.egranth.ac.in/handle/1/5810216209The research work entitled “Standardisation of magnesium nutrition in Bajra Napier hybrid” was undertaken with an objective to assess the influence of magnesium nutrition on growth, yield and quality attributes of Bajra Napier hybrid. The field experiment was carried out during the period October 2020 to April 2021 at Instructional Farm, College of Agriculture, Vellayani. The experiment was laid out in Randomized Complete Block Design with 9 treatments replicated thrice. The treatment comprised of two factors, namely MgSO 4 levels (M) and frequency of application (F). The treatment combinations included three levels of magnesium [m 1 - 80 kg ha -1 , m 2 - 100 kg ha -1 and m 3 - 120 kg ha -1 ] and three frequency of application [f 1 - split application once in 3 months, f 2 - split application once in 4 months and f 3 - split application once in 6 months]. The crop was raised as per the POP recommendations of KAU (25 t ha -1 FYM and 200:50:50 kg ha -1 NPK). The variety used for the study was Suguna, released from Kerala Agricultural University. A total of three harvests were taken during the study period. The results of the study revealed that growth and yield attributes, physiochemical characters, quality characters, nutrient status in soil after the conduct of the experiment, nutrient uptake and economics of cultivation were significantly influenced by varying levels of MgSO 4 application. Application of 100 kg MgSO 4 ha -1 (M 2 ) recorded significantly higher tiller count per hill (23.22), leaf: stem ratio (1.88), green fodder yield (144.35 t ha -1 ) and dry fodder yield (39.5 t ha -1 ). Physiochemical attributes viz chlorophyll content and photosynthetic rate (59.14 μmol CO 2 m -2 s -1 ) in Bajra Napier hybrid were significantly higher in M 2 . Data pertaining to quality characters indicated that crude protein content (9.48 %) in Bajra Napier hybrid was highest in (M 2 ) and was on par with M 3 .Application of 100 kg MgSO 4 ha -1 resulted in highest available phosphorus content (60.47 kg ha -1 ) in the soil and also significantly higher N (454.13 kg ha -1 ), P (48.65 kg ha -1 ) and Mg uptake (189.59 kg ha -1 ). Significantly higher B: C ratio (1.99) was observed in M 2 . However, significantly higher crude fibre content (34.75 %) was observed in M 1 (80 kg MgSO 4 ha -1 ). Similarly available potassium (214.68 kg ha -1 ) and calcium content (251.78 mg kg -1 ) in soil were observed to be significantly higher with application of 80 kg MgSO 4 ha -1 . Significantly higher potassium uptake (398.89 kg ha -1 ) and K: Mg ratio (3.02) were recorded in M 1 . Application of 120 kg MgSO 4 ha -1 (M 3 ) resulted in significantly higher magnesium content (38.22 mg kg - 1 ) in the soil. Frequency of application of MgSO 4 significantly influenced various growth and yield attributes of Bajra Napier hybrid. Highest total green fodder yield (139.59 t ha -1 ) and dry fodder yield (37.14 t ha -1 ), available K status in soil (207.35 kg ha -1 ), NPK uptake and B: C ratio (1.93) were observed with split application of MgSO 4 once in 6 months. Split application of MgSO 4 once in 4 months recorded highest tiller number (22.43) per hill, chlorophyll content, photosynthetic rate (55.71 μmol CO 2 m -2 s -1 ) and highest phosphorus (57.28 kg ha -1 ) and calcium (237.22 mg kg -1 ) content in soil. Highest available magnesium content (40.33 mg kg -1 ) in soil and Mg uptake (171.35 kg ha -1 ) were registered in F 1 (split application once in 3 months). Significantly higher K: Mg ratio (2.44) was observed in F 1 . Among the interactions, m 2 f 3 (100 kg ha -1 MgSO 4 given as split application once in 6 months) recorded highest tiller number (24.72) per hill, total green fodder yield (153.42 t ha -1 ) and dry fodder yield (40.96 t ha -1 ), chlorophyll content, photosynthetic rate, crude protein content (10.06 %), highest nitrogen (480.16 kg ha -1 ) and phosphorus uptake (50.57 kg ha -1 ) and B: C ratio (2.11).Highest available calcium content (257.67 mg kg -1 ) in the soil and potassium uptake (421.10 kg ha -1 ) were observed in m 1 f 3 (80 kg ha -1 MgSO 4 given as split application once in 6 months) and was comparable with treatment m 1 f 2 . The treatment combination m 2 f 2 (100 kg ha -1 MgSO 4 given as split application once in 4 months) registered significantly higher available phosphorus content (73.65 kg ha -1 ) in the soil. The highest soil magnesium content (43.67 mg kg -1 ) was observed in the treatment combination m 3 f 1 (120 kg ha -1 MgSO 4 given as split application once in 4 months). The treatment combination m 2 f 1 (100 kg ha -1 MgSO 4 given as split application once in 3 months) resulted in significantly higher magnesium uptake (201.84 kg ha -1 ). Based on the results of the study, it was revealed that growth, yield, quality parameters, crop nutrient uptake and economics of cultivation in Bajra Napier hybrid were significantly influenced by varying levels and frequency of application of MgSO 4 . It could be concluded that, 100 kg MgSO 4 ha -1 given as split application once in 6 months was the best treatment.EnglishThesis