<div>Background: Time of pre-emergence herbicide application is an important factor that decides the efficiency of herbicide. If the pre-emergence herbicide is not applied at appropriate time, it may cause ineffective weed control or toxicity to crops. With this background, a field experiment was conducted at TNAU, Madurai to optimize the time of pre-emergence herbicides namely pendimethalin and oxyfluorfen application for effective weed management in irrigated blackgram.&nbsp; 
 
Methods: The experiment was laid out in randomized block design with three replication. Treatments were application of pendimethalin at 0.75 kg ha-1 and oxyfluorfen at 0.2 kg ha-1 on 1, 2, 3, 4 days after sowing, weed free check and unweeded check.&nbsp; 
 
Result: Results of the study revealed that oxyfluorfen gave maximum weed control efficiency as compared to pendimethalin, but toxicity to the crop was observed when oxyfluorfen was sprayed after 2 days of sowing. Yield and economics were achieved higher with application of 0.75 kg ha-1 of pendimethalin at 2 DAS, which was on par with application of 0.2 kg ha-1 of oxyfluorfen at 1 DAS due to lesser toxicity. Application of 0.75 kg ha-1 of pendimethalin and 0.2 kg ha-1 of oxyfluorfen didn&rsquo;t leave any herbicide residue after harvest. Hence, application of 0.75 kg ha-1 of pendimethalin at 2 DAS and 0.2 kg ha-1 of oxyfluorfen at 1 DAS can be recommended for effective weed management in irrigated balckgram.</div>

<div>Optimizing the Application Time of Pre-emergence Herbicide Pendimethalin and Oxyfluorfen Application for Effective Weed Management in Irrigated Blackgram (Vigna mungo L.) and Its Residue Persistence</div>

<div>Background: Blackgram is one of the important grain legumes in India. Pulses are the important source of protein for the vegetarian people. To meet out the current demand of pulses, there is a crucial need to increase the blackgram production. Mostly this crop is cultivated in marginal lands where the abiotic stresses like drought and salinity are predominant. The area under salinity in India is 6.73 million hectares and in blackgram no variety was identified as suitable for saline areas. 
 
Methods: This experiment was carried out to study the salinity tolerance levels of balckgram genotypes at vegetative and reproductive stages during Rabi season of 2018-20. A total of six blackgram genotypes were used to screen its performance under saline environment at vegetative and reproductive stage. All the genotypes were raised in pot with the size of 20 cm height and 15 cm width with four replications and salinity were stimulated artificially viz., 4.0 EC, 11.0 EC and 16.0 EC ds/m, its growth habits were observed. 
 
Conclusion: Salinity impact adversely affects blackgram genotypes under study. The number of days to survival of the plant and plant height were decreased by increasing salinity level and number of irrigation with saline water and it was reduced to &frac12; at 16 EC ds/m as compared to control. Days to 50% flowering, chlorophyll content and single plant yield were severally affected by increasing salt concentration. Increasing salt concentration was found directly proportionate to increasing number of days taken for flower initiation and at high level of salinity (16.0 EC ds/m) the plants dried before flowering. The plant yield was much affected by slight increase in salt concentration. At 4.0 EC ds/m level the yield was reduced to &frac14; as compared to control. The 100 grain weight was not much affected by increasing salt concentration; Chlorophyll content also reduced 2/3 by increasing salt concentration after 15 DAS. The genotypes VBG-14-016 performed better under 4.0 EC ds/m level and survived for more number of days followed by the variety VBN 8.</div>

Optimizing the Application Time of Pre-emergence Herbicide Pendimethalin and Oxyfluorfen Application for Effective Weed Management in Irrigated Blackgram (Vigna mungo L.) and Its Residue Persistence

Morphological and Yield Attribute of Blackgram Genotypes under Different Salinity Stress Conditions