Standardization of spacing and nitrogen management of multicut fodder sorghum(Sorghum bicolor x Sorghum sudanense)

Abstract

The study entitled “Standardization of spacing and nitrogen management of multicut fodder sorghum (Sorghum bicolor x Sorghum sudanense)” was undertaken at Instructional Farm, College of Agriculture, Vellayani, during 2021 to 2023. The key objective was to assess the influence of row to row spacing and nitrogen application on growth, yield, and quality aspects of multicut fodder sorghum. The field experiment was carried out at Instructional Farm, College of Agriculture, Vellayani, from November 2022 to August 2023. It was laid out in randomized block design with (3 x 3) + 1 treatments, replicated thrice. The treatment combinations included three levels each of row spacing (R) (r1- 20 cm, r2- 30 cm, r3- 40 cm) and nitrogen application (N) in seven equal splits (n1- 315 kg ha-1, n2- 245 kg ha-1, n3- 175 kg ha-1), compared against the control treatment (30 cm row spacing, nitrogen application- 315 kg ha-1 in seven equal splits, and MgSO4- 80 kg ha-1). Nitrogen was applied in seven splits- as basal, 20, and 40 days after sowing and after each cut. The variety used for the study was COFS-31, released from Tamil Nadu Agricultural University. A total of five cuts were taken during the study period. The treatment, r2 (30 cm row spacing) resulted in significantly taller plants with more leaves at harvest, the longest and broadest leaves, the highest leaf stem ratio, LAI at harvest, LAD, CGR, and RGR (at 30-60 DAS). The treatment, r3 (40 cm row spacing) resulted in the highest stem girth, and SLA (at harvest). Among the levels of nitrogen application, 315 kg N ha-1 (n1) recorded significantly taller plants with more leaves at harvest, the highest leaf length, leaf breadth, leaf stem ratio, stem girth, LAI, and SLA (at harvest), LAD, CGR, and RGR (at 30-60 DAS). Among the treatment combinations, r2n1 (30 cm row spacing + 315 kg N ha-1) resulted in taller plants (235.78 cm), with the highest CGR (30-60 DAS). It resulted in a higher leaf stem ratio (0.55) and was on par with r3n1 (0.53). The treatment combination, r1n1 resulted in the highest LAI (6.19) at harvest. The treatment combination, r3n1 resulted in the highest SLA at harvest. The control treatment was superior over all the treatment combinations concerning growth attributes. The treatments, r2 (30 cm row spacing), and n1 (315 kg N ha-1) resulted in the highest total green fodder yield (148.09 t ha-1 and 159.87 t ha-1 respectively) and dry fodder yield (34.56 t ha-1 and 37.36 t ha-1 respectively). Among the treatment combinations, r2n1 (30 cm row spacing + 315 kg N ha-1) resulted in the highest total green fodder yield (172.58 t ha-1) and dry fodder yield (40.60 t ha-1). The control treatment was superior over all the treatment combinations concerning green fodder yield (175.8 t ha-1) and dry fodder yield (41.52 t ha-1). The treatment, r2 (30 cm row spacing) significantly produced the highest chlorophyll content (1.94 mg g-1) at harvest. Among the levels of nitrogen application, 315 kg N ha-1 (n1) recorded significantly the highest chlorophyll content (1.95 mg g-1), and crude protein percent (9.03 %) at harvest. The control treatment did not show any significant influence on chlorophyll content and crude protein content over all the treatment combinations. The treatments, r2 (30 cm row spacing), and n1 (315 kg N ha-1) resulted in the highest NPK uptake. Among the treatment combinations, r2n1 (30 cm row spacing + 315 kg N ha-1) resulted in the highest NPK uptake. The control treatment was superior to all the treatment combinations concerning NPK uptake. The treatment, r3 (40 cm row spacing) resulted in significantly the highest soil available P and K, higher soil available N, and Mg which were on par with the treatment r1 (20 cm row spacing). The treatment, n3 (175 kg N ha-1) resulted in the highest soil available P, K, and Mg, with higher soil available N, and was on par with the treatment n2 (245 kg N ha-1). Among the treatment combinations, r3n3 (40 cm row spacing + 175 kg N ha-1) resulted in the highest soil available P, K, and higher soil available N which was on par with the treatment combinations r1n1, r1n2, r3n2. Among the treatment combinations, r3n3 (40 cm row spacing + 175 kg N ha-1) resulted in higher soil available Mg which was on par with the treatment combinations r1n3, and r3n2. The treatments, r2 (30 cm row spacing), and n1 (315 kg N ha-1) resulted in the highest benefit cost ratio (2.09 and 2.23 respectively). Among the treatment combinations, r2n1 (30 cm row spacing + 315 kg N ha-1) resulted in a higher benefit cost ratio (2.52) which was comparable with r3n1 (2.32). The control treatment was superior over all the treatment combinations in terms of benefit cost ratio (2.77). Based on the study, it could be inferred that multicut fodder sorghum is suitable for cultivation in Kerala when grown at a row spacing (30 cm) and nitrogen dose of 315 kg ha-1 y-1 (seven equal splits) along with FYM- 10 t ha-1, P2O5- 40 kg ha-1 y-1, K2O- 40 kg ha-1 y-1, and MgSO4- 80 kg ha-1 y-1.