Effect on weed flora
Theexperimental field was infested mainly with 16 different types of weeds. The most problematic and dominating grass, sedge and broad-leaved weeds found in the experimental plot were
Cynodon dactylon (11.74%)
, Cyperus iria (5.2%)and
Cleome viscose (27.86%), respectively.
Effect on weed density and dry weight
At all stages of crop growth, weed-free plot (4 weeding at 20, 40, 60 and 80 DAS) produced minimum weed density, followed by pendimethalin 0.75 kg ha
-1 as PE
fb straw mulch 5 t ha
-1 (Table 1). At 20 and 40 DAS, pendimethalin 0.75 kg ha
-1 as PE
fb straw mulch 5 t ha
-1, straw mulching 10 t ha
-1 at 7 DAS and pendimethalin 0.75 kg ha
-1 as PE produced significantly lower weed density. This might be due to effective weed control by pre-emergence application of herbicide and weed smothering effect of straw mulch during the early stages of crop growth. Among other treatments, manual and mechanical weeding at 20 and 40 DAS resulted in lower weed density, while the weedy check consistently exhibited the highest weed density (114.00 m
-2 and 74.76 m
-2 at 20 and 40 DAS, respectively) throughout crop growth stages. Pre-emergence application of pendimethalin, either solely or combined with straw mulching, consistently showed the least weed density at each growth stage. Similar findings were reported by
Shekhawat et al., (2012), Raj et al., (2020) and Chishi
et al., (2021).
At 20 DAS, the weed-free plot provided the lowest weed dry weight (1.26 gm
-2) followed by pendimethalin 0.75 kg ha
-1 as PE
fb straw mulch 5 t ha
-1 (1.58 gm
-2), which were at par with pendimethalin 0.75 kg ha
-1 as PE (1.74 gm
-2) (Table 1). At 40 DAS also, the weed-free plot recorded the lowest weed dry weight (0.73 gm
-2) which was at par with pendimethalin 0.75 kg ha
-1 fb Straw mulch 5 t ha
-1 (0.84 gm
-2) and straw mulching 10 t ha
-1 at 7 DAS (0.98 g m
-2). Maximum weed biomass was observed in the weedy check at all stages of growth. At 20 and 40 DAS, the weed biomass obtained from the weedy check (15.22 and 7.54 gm
-2 at 20 and 40 DAS, respectively) was significantly higher than other weed control treatments. The weedy check, where no weed control measures were implemented, exhibited increased weed growth and consequently higher weed biomass. However, the application of the herbicide pendimethalin and straw mulching resulted in weed suppression, leading to reduced weed biomass in the field. Similar results were supported by
Shekawat et al., (2012) and
Raj et al., (2020) and
Patel et al., (2020).
Effect on weed control efficiency and weed index
A perusal of the data presented in Table 2 revealed that at 40 DAS, weed control efficiency was highest in 4-weedings plot (90.32%) followed by pendimethalin 0.75 kg ha
-1 as PE
fb straw mulch 5 t ha-1 (88.86%) and straw mulching 10 t ha
-1 at 7 DAS (87%). But at20 DAS, pendimethalin 0.75 kg ha
-1 as PE recorded higher WCE than straw mulching 10 t ha
-1 at 7 DAS which might be due to more effective weed control during the early stages of crop growth by pre-emergence application of pendimethalin.Similar findingswereobserved by
Pandey et al., (2019). Manual weeding at 20 DAS produced the lowest weed control efficiency at all stages of crop growth. The highest weed index was observed in the weedy check (56.75%) followed by manual weeding at 20 DAS (36.29%). The lowest weed index was observed in pendimethalin 0.75 kg ha
-1 as PE
fb Straw mulch 5 t ha
-1 (8.24%) indicating its superiority over other treatments.
Effect on yield
Maximum grain yield was obtained from weed-free plot (1233 kg ha
-1) (Table 3). Among different weed control treatments, pendimethalin 0.75 kg ha
-1 as PE
fb straw mulch 5 t ha
-1 produced the highest grain yield (1131 kg ha
-1) which was significantly higher than straw mulching 10 t ha
-1 at 7 DAS (964 kgha
-1). The lowest grain yield was obtained from the weedy check plot (533 kg ha
-1). In treatments where pre-emergence herbicide was applied or straw mulching was done, weed growth was reduced, so the crop plant had better growth and yield. Similar results were supported by
Kumar et al., (2012), Bamboriya et al., (2017) and
Bijarnia et al., (2017). Maximum stover yield was recorded from weed-free plot (2406 kg ha
-1) (Table 3). Among various weed management treatments, the highest stover yield was obtained from pendimethalin0.75 kg ha
-1 as PE
fb straw mulch 5 t ha
-1 (2303 kg ha
-1) which was statistically at par with straw mulching 10 t ha
-1 at 7 DAS (2229 kg ha
-1). Stover yield was lowest in the weedy check (1347 kg ha
-1).
Economics
Production economics is the main deciding factor for the adoption of a technology by the farmers. New technology aims at reducing the cost of cultivation with increasing yield, net return and B: C ratio.The highest benefit-to-cost ratio was found under pendimethalin 0.75 kg ha
-1 as PE
fb straw mulch 5 t ha
-1 (1.96) followed by pendimethalin 0.75 kg ha
-1 as PE (1.89) (Table 3). Weedy check recorded the minimum value of 1.11. These findings conform with
Singh et al., (2002), Degra et al., (2011) and
Raj et al., (2020). Despite the weed-free plot yielding the highest in terms of both yield and gross returns, the B:C Ratio waslow. This wasdue to the high cost of manpower involved.