| Abstract |
The research entitled “Irrigation and crop establishment techniques in Bajra Napier hybrid” was conducted at Department of Agronomy, College of Agriculture, Vellayani, during 2022 to 2025. The major objectives of the study were standardization of irrigation levels for popular Bajra Napier hybrid varieties in Kerala and standardization of sett size, age and method of planting of Bajra Napier hybrid. The study was undertaken as two separate parts. Part 1 entitled “Standardization of irrigation levels for popular Bajra Napier hybrid varieties in Kerala” was conducted from March 2023 to August 2024 at Instructional Farm, College of Agriculture, Vellayani. The experiment was laid out in split plot design with 4 main plots (i1 - IW/CPE- 1.00, i2 - IW/CPE- 0.80, i3 - IW/CPE- 0.60 and i4 - Rainfed), 3 sub plots (v1 – Susthira, v2 – Suguna and v3 – CO-5) and three replications. Crop was irrigated to a depth of 2.5 cm. Initial 6 months was taken as establishment period and after that, observations were recorded for 12 months. The results revealed that irrigation scheduling at IW/CPE ratio of 1.0 significantly enhanced the growth attributes including mean plant height, number of tillers per hill, leaf stem ratio (1.85), leaf area, and leaf area index compared to lower irrigation levels. Among the varieties, CO-5 consistently recorded superior growth performance, achieving the highest mean plant height (208.07 cm), leaf stem ratio (1.69), leaf area (228.87 cm²), and leaf area index (12.13). The mean number of tillers per hill was the highest in Suguna (v2). Among the interactions, CO-5 irrigated at an IW/CPE of 1.0 (i1v3) yielded the highest growth values like mean leaf stem ratio, leaf area and leaf area index. The results on yield revealed that total green and dry fodder yield were the highest in irrigation at an IW/CPE of 1.0 (175.45 t ha-1 and 40.95 t ha-1, respectively). Variety CO-5 (v3) produced the highest total green fodder (186.74 t ha-1) and dry fodder yield (39.05 t ha-1). Among the treatment combinations, i2v3 (CO-5 at an IW/CPE of 0.8) recorded the higher total green fodder (206.06 t ha⁻¹) and dry fodder (51.26 t ha⁻¹) yield, and remained comparable with i1v3. Across all harvests, green fodder yield and dry fodder yield followed a declining trend from the first to the fifth cut, with consistently higher yields recorded under IW/CPE of 1.0 and CO-5 variety at each harvest. Root studies revealed that rainfed conditions encouraged deeper rooting (46.56 cm), whereas irrigation at IW/CPE 1.0 improved root biomass (318.83 g per plant), with CO-5 exhibiting superior root dry weight (389.08 g per plant). Among the interactions, the treatment combination of rainfed irrigation with variety CO-5 (i4v3) recorded the deepest roots (51.73 cm). Conversely, the highest root dry weight (503.83 g per plant) was recorded in the combination of IW/CPE 1.0 with CO-5 (i1v3). Biochemical analysis showed significantly higher chlorophyll content in treatments involving IW/CPE 1.0 and CO-5, although crude protein content remained unaffected by treatments. Lower crude fibre content was noticed in IW/CPE of 0.8 (29.91%) and was on on par with i1. Crude protein yield was the highest in i1v3 (IW/CPE of 1.0 in CO-5) recording the maximum crude protein yield of 4739 kg ha⁻¹, which was statistically on par with i2v3. Analysis of post-experiment soil showed no significant effect for interactions in soil pH, electrical conductivity, organic carbon and available N. However, available phosphorus was the highest under rainfed conditions (i4). Interaction between irrigation levels and varieties also influenced soil potassium status, with i1v3 (IW/CPE of 1.0 x CO-5 variety) recording the highest value. Nutrient uptake studies revealed that nitrogen, phosphorus, and potassium uptake closely followed the same trend as that of dry fodder yield, with the highest uptake under IW/CPE of 1.0 and in the variety CO-5, particularly in the treatment combination i1v3 (CO-5 at an IW/CPE of 1.0). The water use efficiency and economic water productivity was found to be higher in irrigation scheduling at IW/CPE ratio of 0.8 (45.67 kg ha-1 mm-1 and 161.55 ₹ ha-1 mm-1) and it was on par with IW/CPE ratio 1.0. Among varieties, CO-5 recorded higher WUE and economic water productivity. CO-5 irrigated at an IW/CPE of 0.8 recorded higher WUE and the highest economic water productivity. Economic analysis showed that CO-5 irrigated at an IW/CPE of 0.8 (i2v3) achieved the highest net returns (348655 ₹ ha-1) and B: C ratio (1.94). The part II of the study for “standardization of crop establishment methods in Bajra Napier hybrid” was conducted from June to October 2023 and the confirmatory trial was conducted from June – October 2024 at Instructional Farm, College of Agriculture, Vellayani. The experiment was laid out in randomized block design with 3 factors and at three levels each, replicated thrice. The treatments comprised three levels of nodes per cutting (n1 – Single noded cutting, n2 – Two noded cutting, n3 – Three noded cutting), three planting method (p1 – Horizontal planting, p2 - Vertical planting, p3 – Planting at 45 degree) and three stages of maturity (s1 – 3 months, s2 – 4 months, s3 – 5 months). The observations were recorded to two harvests and the variety used for the study was Susthira. The results revealed that growth, yield, establishment, and economics were significantly influenced by nodes per cutting, planting methods, stage of maturity and their interactions. Among the nodes per cutting, three noded cutting (n3) recorded tallest plants (170.93 and 227.72 cm respectively), mean number of tillers per hill (8.92 and 8.32 respectively), leaf stem ratio, leaf area, LAI (8.07 and 8.54 respectively), total green fodder yield (88.49 and 85.27 t ha-1 respectively) and total dry fodder yield (22.12 and 21.32 t ha-1 respectively) in first and second year. But the specific leaf area was the highest in single noded cutting (n1). Among the planting methods, horizontal planting (p1) recorded the highest mean number of tillers per hill, leaf stem ratio, LAI, mean specific leaf area, total green fodder yield (92.78 and 90.84 t ha-1 respectively), total dry fodder yield (23.19 and 22.71 t ha-1 respectively) and crude protein yield (2032 and 2131 kg ha-1 respectively) in first and second year. Among the stages of maturity, cuttings from 4 month old plants (s2) recorded the highest number of tillers per hill, leaf stem ratio, LAI, total green (85.91 and 86.30 t ha-1 respectively) and dry fodder yield (21.48 and 21.57 t ha-1 respectively) and crude protein yield (1892 and 2034 t ha-1 respectively) in first and second year. The lowest number of days for first harvest (75 days in both years) was observed in 4 month old cutting (s2). Horizontal planting of three noded cutting taken from 4 month old plants (n3p1s2) recorded the highest mean number of tillers per hill, mean leaf stem ratio, mean LAI, total green (156.46 and 155.80 t ha-1 respectively) and dry fodder yield (39.12 and 38.95 t ha-1 respectively) and crude protein yield in both years. Among the establishment characters, 4 month old cutting (s2) established earlier (10.33 and 10.52 respectively) in both years. The treatment combination n3p1s2 (horizontal planting of three noded cutting taken from 4 month old plants) recorded higher establishment percentage in first and second year. The economic analysis revealed that, horizontal planting of three noded cutting taken from 4 month old plants (n3p1s2) recorded the highest B: C ratio in first (3.91) and second (3.89) year. It could be concluded that, among the Bajra Napier hybrid screened, the variety CO-5 irrigated at an IW/CPE of 0.8 could be recommended for realizing higher green fodder yield, dry fodder yield, WUE, economic water productivity, net returns and B:C ratio. In Bajra Napier hybrid variety Susthira, horizontal planting of three noded cutting taken from 4 month old plants could be adjudged as the best establishment method for higher growth, yield, establishment and B:C ratio.
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