Navneet KaurParija, Bhadra2024-01-042024-01-042022Parija, Bhadra (2022). Effect of agronomic manipulations on crop productivity and weed dynamics in poplar (Populus deltoides Bartr.) based agroforestry system (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810205645Present study entitled “Effect of agronomic manipulations on crop productivity and weed dynamics in poplar (Populus deltoides Bartr.) based agroforestry system” was carried out at Punjab Agricultural University, Ludhiana and KVK, Roopnagar (Experiment I) during 2017- 18 and 2018-19. Experiment I consisted of crop establishment methods of wheat viz. two methods of sowing (line sowing and broadcasting) and two seed rates (100 kg/ha and 125 kg/ha) along with five weed control treatments viz. carfentrazone 20 g/ha, pinoxaden 50 g/ha, clodinafop+metribuzin 270 g/ha, weed free check and weedy check in factorial RBD with 3 replications. The age of the poplar tree was 4 years in Ludhiana with 12.4 m height and 15.8 cm diameter at breast height (dbh) while at Roopnagar the age of the plantation was 3 years with an average 9.3 m height and 12.1 cm dbh during 2018-19. Experiment II consisted of planting geometry viz. two poplar spacings (8m×2.5m and 7m×3m, paired at 2.5m) and two potato planting geometry (65cm×18.5cm and 75cm×15cm) in main plots and weed control treatments (atrazine 0.250 kg/ha, metribuzin 0.350 kg/ha, paraquat 0.300 kg/ha, clodinafop+metribuzin 0.270 kg/ha, weed free check and weedy check) in sub-plots with three replications in split-plot design. The age of the poplar here was 6 years old with 19.6 m height and 26.5 cm DBH during 2018-19. The results of experiment I revealed that line sown wheat (38.0-42.8 q/ha) with higher seed rate of 125 kg/ha (37.3-41.5 q/ha) under weed free check (40.2-45.4 q/ha) had higher yield advantages with a greater number of effective tillers, spike length, grains/ear and 1000-grain weight in comparison to broadcasted with lower seed rate wheat crop under the rest weed control treatments and it was statistically at par with clodinafop+metribuzin 270 g/ha (36.5-41.3 q/ha) applied treatments. The application of clodinafop+metribuzin 270 g/ha effectively reduced the weed count and biomass. In experiment II, poplar spacing of 8m×2.5m (263.5-272.0 q/ha) and potato planting geometry of 75cm×15cm (256.6-262.1 q/ha) recorded significantly higher potato tuber yield. Among the weed control treatments weed free check (294.9-302.9 q/ha) was at par with clodinafop+metribuzin 0.270 kg/ha (289.4-293.2 q/ha) in terms of potato tuber no., weight/hill and yield. These treatments have exhibited a higher weed smothering effect thereby subsequently reduced the weed seed bank and seed recruitment in both the experiments. All the herbicides used in both the experiments temporarily reduced the microbial population and their activity upto 90 days of application and then it recovered till harvesting of the intercrops.EnglishThesis