Effect of Integrated Weed Management Practices on Weed Dynamics, Growth Performance and Yield of Direct Sown Finger Millet (Eleusine coracana L.)

Finger millet is scientifically called as Eleusine coracana belongs to poaceae family. It covers 5% of all cereal-growing land (Shinggu et al., 2009). In India, finger millet is cultivated in an area of 1.15 million ha with a yield of 1724 kg ha^-1 and a production of 1.99 million tonnes during 2020-21 (Indiastat, 2022). Due to crop weed competition and critical crop weed days observed between 25 and 45 days in direct seeded finger millet further sowing causes a greater reduction in yield. Weeds that grow alongside crops deplete a significant amount of plant nutrients, resulting in lower crop yields. The integration of chemical and cultural control further increased the weed control and enabled that herbicide rates to be reduced (Anonymous, 2004). Several new generation pre-emergence herbicides have been reported to provide appropriate weed control when used alone or in combination with hand weeding or chemical. The twin wheel hoe has two wheels for easy movement while removing unwanted plants and weeds that have overgrown the crop grown in the field. In this context, an experiment has been carried out to investigate the effect of integrated weed management practices in direct sown finger millet.

A field experiment was conducted during Rabi season of 2022-23 in field no. R₂₄ at Karunya Institute of Technology and Sciences, Coimbatore. The experimental site is geographically located in Western agro-climatic zone of Tamil Nadu at 10°56'N latitude and 76°44'E longitude with 474 m above MSL. The soil was clay loam in texture with neutral soil pH (6.9). The available nitrogen is 336 kg ha^-1, phosphorus is 91 kg ha^-1 and potassium are 261 kg ha^-1. The organic content was 0.37%.
       
The experiment was laid out in randomized complete block design with ten treatments and three replications viz., T₁: PE pendimethalin @ 0.75 kg ha^-1 8 DAS + Hand weeding (HW) @ 35 DAS, T₂: PoE 2, 4-D @ 2 kg ha^-1 40 DAS + Hand weeding (HW) @ 35 DAS, T₃: PE pretilachlor @ 0.75 kg ha^-1 8 DAS + Hand weeding (HW) @ 35 DAS, T₄: PoE 2,4-D @ 2 kg ha^-1 40 DAS + Twin wheel hoe weeding (TWHW) @ 30 DAS, T₅: PE pendimethalin @ 0.75 kg ha^-1 8 DAS + Twin wheel hoe weeding @ 30 DAS, T₆: PE pretilachlor @ 0.75 kg ha^-1 8 DAS + Twin wheel hoe weeding (TWHW) @ 30 DAS, T₇: Hand weeding (HW) @ 25 and 40 DAS, T₈: Twin wheel hoe weeding (TWHW) @ 25 and 40 DAS, T₉: Hand weeding (HW) @ 25 DAS + Twin wheel hoe weeding (TWHW) @ 40 DAS, T₁₀: Unweeded control.
       
Finger millet CO 14 with a medium duration of 110 days was used which was sown at 30 cm × 15 cm spacing. The data on total weed density, importance value index and summed dominance ratio was observed and calculated using the following formulas suggested by Raju (1997). Observation on growth parameters and yield at harvest were recorded. The data obtained in the study were statistically analyzed using AGRES at 5% level of significance suggested by Gomez and Gomez (1984).
 
Absolute density
   
Relative density
   
Importance value index
   
Summed dominance ratio
 

Plant height
 
Fig 1 shows among different IWM T₆ recorded significantly higher plant height of 115.8 cm which was on par with T₅ (114.2 cm) followed by T₃ (105.4 cm) at harvest. This may be the result for effective weed management techniques that reduce weed growth, allowing the crop to better utilize nutrients, moisture, space and light which resulting in improvement of plant height (Fig 1). Similar observation was observed by Prithvi et al., (2015). T₁₀ shows the lowest plant height of 75.1 cm. This might be due to severe crop weed competition for the resources during earlier stages of crop growth. These outcomes were confirmed with the findings of Madhukumar et al., (2013).
 

 
Grain yield
 
Different IWM significantly influenced grain yield in finger millet (Fig 1). T₆ recorded highest grain yield 2368 kg ha^-1 which was statistically comparable with T₅ recorded grain yield of 2209 kg ha^-1. Higher grain yield in this treatment was due to better control of weed growth in all stages of finger millet (Sunil et al., 2010). T₁₀ records lower grain yield (698 kg ha^-1). The yield was adversely affected in unweeded control due to severe weed competition by weed for space, light, moisture and nutrients throughout the crop growth period. These findings are similar with (Pradhan et al., 2012).
 
Absolute density (AD)
 
Table 1 shows that among different IWM carried out to control the grassy weeds the lowest AD was recorded in T₆ (3.4 no m^-2) which was on par with T₅ recorded 3.8 no m^-2 followed by T₃ (4.4 no m^-2). Kujur et al., (2019) observed that higher herbicide use efficiency was owing to superior weed control. The highest AD was noticed in T₁₀ (17.9 no m^-2).
 

       
The AD among sedges was lowest in T₆ recorded 2.2 no m^-2 which was on par with T₅ (2.7 no m^-2) followed by T₃ (3.2 no m^-2). The lowest AD was mainly due to better control of weeds from sowing to 45 DAS, which is the critical period for crop weed competition. These results are in conformity with Prashanth (Kumar et al., 2015). T₁₀ recorded the highest AD of 17.2 no m^-2.
       
The AD of BLW was significantly reduced by different IWM the lowest AD was observed in T₆ (5.6 no m^-2) followed by T₅ (6.1 no m^-2). Highest AD was noticed in T₁₀ (15.6 no m^-2). Integrated application of pre-emergence herbicides along with inter-cultutal operations viz., hoeing and hand weeding at 30 to 35 days after sowing of seeds will give an effective and economical results of controlling weeds (Mishra et al., 2018). Similar findings were observed by (Satish et al., 2018).
 
Relative density (RD)
 
Adoption of IWM on grasses significantly influenced the RD of the weeds (Table 2). The lowest RD of grassy weeds was observed in T₆ recorded 98 % which was followed by T₅ (102%) which was on par with T₃ (104%). T₁₀ shows the highest density of 159% (Table 2). Similar results were also found by Mynavathi et al., (2008) in irrigated maize discovered that, when compared to other mechanical weeders, passing wheel hoe greatly decreased the weed dry weight and enhanced the maize yield. This study findings were consistent with those made before by Ramamoorthy et al., (2009) in finger millet.


       
The lower RD was observed in T₆ (115%) which was followed by T₅ (129%) IWM measures drastically reduced weed population and weed dry matter at initial as well as up to final stages of the finger millet. T₁₀ recorded higher RD of 203%.
       
The BLW show significant difference in the RD. Lowest density was found in T₆ (83%) followed by T₅ (93%) were on par with T₃ (98%). IWM with combination of herbicides, mechanical and hand weeding provide efficient weed control. Similar findings were done by (Rao, 2021). Highest values were recorded in T₁₀ (137%).
 
Importance value index
 
The lowest IVI of grassy weeds presented in Table 3 were recorded in T₆ (148%) followed by T₅ (152%). The lowest IVI recorded plots could be due to less weed growth by controlling the early emergence of weeds by pre-emergence application of herbicides and late emerged weeds through inter-culture activity. Similar results were reported by Prashanth Kumar et al., (2015). Highest was recorded in T₁₀ (209%).
 

       
Among the sedges the lowest IVI value was recorded in T₆ (135%) The lowest range of IVI value through effective weed management practices in finger millet. Similar finding by Patil and Reddy (2014). Higher values were found in T₁₀ (223%).
       
Among the different IWM the lowest IVI value was found in T₆ recorded 133 % followed by T₅ was on par with T₃ recorded 143 % and 147 %. The pre-emergence application of herbicides combined with a timely inter cultivation at 25-30 days after sowing provides effective weed control and higher yield leading to higher returns (Mishra et al., 2016). Highest was recorded in T₁₀ (186%).
 
Summed dominance ratio (SDR)
 
The SDR of grassy weeds presented in Table 4 are lower in T₆ (74) which was on par with T₅ followed by T₃ (76.1 and 77). Highest was recorded in T₁₀ (104).
 

       
Among different IWM on sedges the SDR found lowest in T₆ (67.8) followed by T₅ recorded 74.7. The timely control of weed during the early emergence is very much essential for good yield this can be achieved by using mechanical weeders which can reduce the time spent on weeding (Goel et al., 2008). The highest was observed in T₁₀ (111).
       
The lowest SDR value was noticed in in T₆ (66.5) followed by T₅ recorded (71.7). Because of highest cost and non-availability of labours the integrated use of herbicides and mechanical weeding for weed control at all stages proved to be an appropriate strategy for finger millet stated by Yadav et al., (2005). Similar findings were done by (Gowda et al., 2012). T₁₀ recorded highest value 93.4.

The study revealed that PE pretilachlor @ 0.75 kg ha^-1 on 8 DAS + TWHW on 30 DAS shows reduced absolute weed density, relative weed density, importance value index and summed dominance ratio in finger millet. The same treatment recorded higher plant height and grain yield of finger millet. Hence it was concluded that PE application of pretilachlor @ 0.75 kg ha^-1 on 8 DAS + TWHW on 30 DAS had a remarkable effect in increasing productivity and profitability in direct sown finger millet production under irrigated condition.

All authors declare that they have no conflicts of interest.