Effect on weed density
The efficiency of different sorghum extract and herbicidal treatments on density of different weed species and total weed density resulted in significant variation on its count at each stage of the crop growth except at 30 DAS (Table 1, 2 and 3). Data revealed that sequential and post-emergence application of sorghum extract (1:3) + ready-mix of clodinafop + metsulfuron 64 g/ha recorded significantly lower density of
Chenopodium murale (2.03, 1.63 and 1.51/m
2),
Chenopodium album (2.02, 1.42 and 1.32/m
2),
Asphodelus tenuifolius (2.36, 1.85 and 1.47/m
2),
Cyperus rotundus (1.85, 1.63 and 1.36/m
2) and
Rumex dentatus (1.56, 1.29 and 0.92/m2) which was at par with sorghum extract (1:2) + ready-mix of clodinafop + metsulfuron 64 g/ha. Alone application of sorghum extract also found effective in reducing weed density as compared to weedy check. Sorghum extract affecting several physiological processes including inhibition of nutrient uptake, mitotic inhibition, photosynthetic inhibition in weed plant
(Naeem et al., 2018). Sequential application of sorghum extract (1:3) + ready-mix of clodinafop + metsulfuron 64 g/ha significantly reduces total weed density (4.20, 3.27 and 2.66/m
2) which was closely by sorghum extract (1:2) + ready-mix of clodinafop + metsulfuron 64 g/ha which also outplayed in reducing total weed density (5.57, 4.77 and 4.29/m
2) at different growth stages of wheat (Table 3). Clodinafop-propargyl is basically
Acetyl Co-A carboxylase (ACCase) inhibitor most effective in controlling annual grassy weeds in wheat. Metsulfuron-methyl is basically an
Acetolactate Synthase (ALS) enzyme inhibitor, a enters into the plant through root as well as foliage. This results in rapid inhibition of cell division and growth in the plant (
Das, 2015).
Effect on total weed dry weight
Data pertaining to total dry weight of weeds recorded at 30, 60, 90 DAS and at harvest indicated marked variations due to integrated application of different dilution level of sorghum extract and herbicidal treatments at all growth stages except at 30 DAS (Table 4). Post-emergence application of sorghum extract (1:3) + ready-mix of clodinafop + metsulfuron 64 g/ha recorded significantly lesser quantity of total weed dry weight (2.99, 3.15 and 3.55 g/m
2) followed by the treatment sprayed with sorghum extract (1:2) + ready-mix of clodinafop + metsulfuron 64 g/ha, which also showed their significant effects on reducing total weed dry weight (3.35, 3.72 and 4.01 g/m
2) different growth stages of wheat (Table 4). Alone application of sorghum extract also found effective in reducing weed dry weight as compared to weedy check. It was might be duet to sorghum extracts reduces weed dry weight by affecting several physiological processes including inhibition of nutrient uptake, mitotic inhibition, photosynthetic inhibition, effects on membrane permeability and production of reactive oxygen species that weaker the weeds through improper assimilation and their storage in the sink. Similar results were reported by
Naeem et al., (2018), Singh et al., (2017). clodinafop-propargyl able to control grass weeds in wheat, triticale and rye. Metsulfuron-methyl basically is an
Acetolactate Synthase (ALS) enzyme inhibitor, a key enzyme required in the biosynthesis of essential amino-acids
viz. valine and isoleucine in plant. This results in rapid inhibition of cell division and growth in the plant (
Das, 2015).
Effect on weed control efficiency
Higher weed control efficiency was recorded with sequential application of sorghum extract (1:3) + ready-mix of clodinafop + metsulfuron 64 g/ha which was by sorghum extract (1:2) + ready-mix of clodinafop + metsulfuron 64 g/ha at all growth stages of crop at their respective sequence and attained highest efficacy (Table 5). This may be due to sorghum extract and herbicidal treatments supress the weed growth and provided favourable conditions for crop growth which ultimately increased the grain yield of wheat. Similar trends in weed control efficiency were also recorded by
Desmukh et al., (2020).
Effect on weed index
Lower weed index was recorded post-emergence and sequential application of sorghum extract (1:3) + ready-mix of clodinafop + metsulfuron 64 g/ha which was by sorghum extract (1:2) + ready-mix of clodinafop + metsulfuron 64 g/ha also showed minimum yield loss in terms of weed index (Table 5). The loss of yield was maximum was observed under weedy check due to heavy infestation of weeds. Similar trends in weed index were also recorded by
Desmukh et al., (2020). These results were in lines that alllelopathic compounds of sorghum mostly kills all species of weeds in wheat crop through inhibits overall functions of chloroplast and mitochondrial.
(Cheema et al., 2020).
Effect on grain yield
Significantly higher grain yield of wheat was obtained with weed free this might be possible due to season long weeding which could be attributed toward better utilization of applied inputs. Thereafter, sequential application of sorghum extract (1:3) + ready-mix of clodinafop + metsulfuron 64 g/ha as post emergence, recorded significantly higher grain yield 4543 kg/ha with 34.87% increase in yield magnitude of increments were 34.87% over weedy check which was at par with sorghum extract (1:2) + ready-mix of clodinafop + metsulfuron 64 g/ha (Table 5). Sorghum extract and herbicide suppress the initial growth of weed and increase the nutrient availability by crop as well as increase metabolic functions like cell division and photosynthesis, which resulted in higher.
Naby and Ali (2020).
Regression studies
It was noticed that grain yield of wheat negatively correlated with weed index that shown correlation co-efficient of 1.00. This was further supported by the regression analysis; the grain yield of wheat was decreased by 48.507 kg/ha (Fig 1) in terms of weed index. The grain yield and weed control efficiency was positively correlated with correlation co-efficient of 0.699. This was further proved by regression analysis; the grain yield of wheat was increased by 16.85 kg/ha (Fig 2).