MSc

ABSTRACT

The study entitled “Weed management in Bajra Napier hybrid (Pennisetum glaucum x Pennisetum purpureum)” was carried out during 2018-2020, at College of Agriculture, Vellayani, Thiruvananthapuram, Kerala with an objective to standardise an economic weed management strategy for Bajra Napier Hybrid.
The experiment was laid out in randomized block design (RBD) with 9 treatments in three replications during July 2019 to January 2020. The treatments were T1: oxadiargyl 60 g ha-1 on 3-5 DAP fb carfentrazone ethyl 20 g ha-1 on 25-30 DAP, T2: oxadiargyl 90 g ha-1on 3-5 DAP fb carfentrazone ethyl 20 g ha-1on 25-30 DAP, T3: oxadiargyl 120 g ha-1 on 3-5 DAP fb carfentrazone ethyl 20 g ha-1 on 25-30 DAP, T4: oxadiargyl 60 g ha-1 on 3-5 DAP fb hand weeding on 25 - 30 DAP, T5: oxadiargyl 90 g ha-1 on 3-5 DAP fb hand weeding on 25 - 30 DAP, T6: oxadiargyl 120 g ha-1 on 3-5 DAP fb hand weeding on 25 - 30 DAP, T7 : biomulching, T8 : farmers practice (hand weeding at 20 and 40 DAP and T9: weedy check. The variety used for the study was Suguna, released from Kerala Agricultural University.
Among the weed management practices, T5 recorded the lowest weed count, relative density, dry weight and the highest weed control efficiency at 25 and 50 DAP. Plant height was significantly influenced by weed management practices. At first harvest (75 DAP), second harvest (120 DAP) and third harvest (165 DAP), treatment T5 (oxadiargyl 90 g ha-1 on 3-5 DAP fb hand weeding on 25 - 30 DAP) recorded the highest plant height which was on par with T2 (oxadiargyl 90 g ha-1on 3-5 DAP fb carfentrazone ethyl 20 g ha-1on 25-30 DAP).
The treatment T5 recorded the highest leaf area, number of tillers per plant and tussock diameter per hill at all the three harvests (75, 120 and 165 DAP). Leaf stem ratio was found higher in T5 during first, second and third harvests. The treatments T9, T8 and T7 recorded the highest leaf chlorophyll content at first, second and third harvest. Crop growth rate (CGR) was also significantly influenced by weed management practices and the treatment T5 recorded the highest CGR at both the time intervals (25-50 DAP and 50- 75 DAP). However, RGR was not significantly influenced by weed management practices at both the time intervals.

The highest N, P and K uptake was recorded in T5. The highest green fodder yield (154.84 t ha-1), dry fodder yield (30.96 t ha-1), net return (Rs. 123758.5 ha-1) and B:C ratio (1.66) and the lowest weed index was recorded in T5 (oxadiargyl 90 g ha-1 on 3-5 DAP fb hand weeding on 25 - 30 DAP).
The highest crude protein content (9.7%) and the lowest crude fibre content (35.2%) was recorded in T2 (oxadiargyl 90 g ha-1on 3-5 DAP fb carfentrazone ethyl 20 g ha-1on 25-30 DAP). Available soil nutrient status was also significantly influenced by weed management treatments. The treatment T7 recorded the highest soil organic carbon content, T9 recorded the highest soil available nitrogen and potassium and T4 recorded the highest soil available phosphorus.
Hence considering the growth, physiological and yield parameters, weed control efficiency, weed index, net return and B: C ratio, the treatment T5 (oxadiargyl @ 90 g ha-1 on 3-5 DAP fb hand weeding on 25-30 DAP) could be adjudged as the economic weed management practice in Bajra Napier hybrid.