Efficacy of Various Herbicides and their Concentration on Weed Management of Linseed in India

Linseed is under cultivation since prehistoric times in the world. India is the largest (21.42%) linseed growing country in the world where it is grown in an area of 3.39 lakh hectares predominantly in the states of Madhya Pradesh, Maharashtra, Chhattisgarh, Uttar Pradesh, Bihar, Orissa and Jharkhand, besides other states on a limited scale. Linseed is an industrial oilseed crop grown during rabi season. Linseed has poor foliage and never forms a canopy; therefore, it remains a poor weed competitor throughout its life. Flax does not compete well with weeds because it produces little shade and uses water and soil nutrients less efficiently than most weed species. Weeds are a major impediment to crop production through their ability to compete for resources and their impact on product quality and are the major factors, which cause yield reduction of 15-50%, depending on weed density and type of weed flora and makes the weed control more complex. Herbicides are the most successful weed control technology ever developed. No doubt weed control through chemicals is easy, economical and labour efficient, the over dependence resulted in some serious environmental and ecological implications and continuous use of herbicides for weed control leads to residue hazards, weed shift and build-up of resistance in weeds. Weeds should be controlled when the crop height is between 5 and 10 cm. There are a number of herbicides recommended for efficient control of weed flora in irrigated linseed. Keyword: Herbicides, Flex, Linseed, Crop-weed competition. Review Article Cite this article: Nagar, R., Bhatnagar, G. S., Trivedi, S. K., Meena, R. K., & Nagar, D. (2020). Efficacy of Various Herbicides and their Concentration on Weed Management of Linseed in India, Curr. Rese. Agri. Far. 1(4), 47-51. doi: http://dx.doi.org/10.18782/2582-7146.122 Nagar et al. Curr. Rese. Agri. Far. (2020) 1(4), 47-51 ISSN: 2582 – 7146 Copyright © Nov.-Dec., 2020; CRAF 48 In order to minimize the losses caused by weeds and also to reduce the sole dependence on costly and controversial inputs such as herbicides, considerable interest has aroused recently throughout the world in evolving technologies, which are within the reach of common farmers. Which is ecologically sound and socially acceptable. The recent awareness is to minimize the use of herbicides for weed management due to higher cost of cultivation (weeding). Flax does not compete well with weeds and thus needs extensive management for effective weed control. Flax does not rapidly cover the soil surface allowing weeds to recruit later within the season and outcompete it for nutrients and space. Weed competition not only reduces yield but also leads to higher dockage within the grain because of high amounts of weed seed. Reduced yields are likely if weeds are not controlled within the first stages of plant growth. Weed control is required by the time flax emerges to reduce yield losses, since flax could also be a poor competitor with weeds. Pre-plantincorporated (PPI) herbicides prevent weed emergence, minimize early weed competition, and maximize flax yields. Post emergence herbicides applied soon after weed emergence to small weeds and flax usually give better control and permit longer for flax recovery from possible herbicide injury than to larger weeds and flax. Losses caused due to weeds in linseed Weed causes great yield losses to crop, especially where a monoculture cropping systems is practice. At early stage, linseed cannot compete effectively with weeds, especially up to two months after sowing. Early removal of weeds is important before flowering because a yield reduction of up to 56% can be caused depending on the infestation level (Rezene, 1992). In general, all weed species do not equally contribute to this loss, so, it is based on weed distribution and abundance of weed species. Weed growth, population and distributions vary from place to places depending up on soil and climate factors. The difference in the effect of weeds on crops production is mainly due to differences in characteristics and competitive status of the weeds and the crop, i.e. the ability of plants to obtain and use the growth determining and limiting resources, namely, light, water and nutrients Long kumer and Singh (2013) reported that the crop management factors employed on the preceding crop of rice had significant impact on the expansion and yield of linseed. Residual effect of certain agronomic management aspects like nutrition and weed management in rice crop had significant effect on the productivity of linseed. N2-75% NPK (recommended)+Azospirillum & Phosphotika and Butachlor @ 1.5 kg ha-1 (PE) significantly recorded superior values in production of number of branches plant-1, dry weight plant-1, number of balls plant-1 and seed yield (7.03 q ha-1 and 7.21 q ha-1) of succeeding linseed. Among the weed management practices, W3-Butachlor @ 1.5 kg ha-1 (PE) recorded the utmost net return (40,020/ha-1) and benefit: cost ratio (2.00) than that of other weed management practices. Factors of crop weed competition The composition and competition by weeds is dynamic and is dependent on soil, climate, cropping and management factors. Water, mineral nutrients, and light are important environmental factors affecting plant competition and according to Clements, if the supply of any of these factors falls below the combined needs of the competing plants, competition begins. Competition for space Pali et al. (1997) noticed that the less competition of associated weeds for space might be the reason of increased branching in treated plots than in unweeded plots. Hussein et al. (2002) reported that weed competition caused a significantly lower seed, straw and oil yield (29.6, 26.2 and 32.0%, respectively). Competition for moisture Mohammad et al. (2012) studied to determine the effect of planting date and irrigation stress on two spring varieties of flaxseed. The Highest capsule numbers per plant (65.9), seed Nagar et al. Curr. Rese. Agri. Far. (2020) 1(4), 47-51 ISSN: 2582 – 7146 Copyright © Nov.-Dec., 2020; CRAF 49 numbers per capsule (5.78), seed yield (1763 kg/ha), biological yield (5935 kg/ha), harvest index (29.9) Were obtained in first sowing date and under full irrigation by later sowing dates and limited irrigation stress especially at flowering and grain filling stages, this characters Were reduced. Competition for light Plant height and vertical leaf area distribution define effective components of the competitive struggle for light. It becomes most vital element of weed-crop competition when moisture and nutrients in soil are plentiful, and weeds have a foothold over crop plants in respect of their height. Dubey et al. (2009) conducted an experiment at three locations i.e., CSK HPKV, Palampur, CSAUA&T, Kanpur and UAS Regional Station, Raichur. Maximum oil content was recorded at Palampur where the range of maximum and minimum temperature Were but that of Kanpur and Raichur locations. The oil content was found in decreasing trend with the rise of temperature. Competition for nutrient Weeds, which emerge simultaneously with crop plants absorb fertilizer nutrients faster and comparatively in larger, amount than crop, thereby depriving the crop of obtainable nutrients leading to poor yields. Competition for nutrients constitutes a crucial aspect of weed-crop competition. Weeds deplete considerable amount of nutrient from the soil and thereby offering severe competition for crop growth and development. Rao and Nagamani (2010) opined that weeds generally have higher content of nutrients than crop plants. They grow and absorb nutrients faster than crop with the result that there could also be a scarcity of nutrient for the crop plants. Effect of different herbicides for weed control in linseed Linseed has poor foliage and never forms a canopy; therefore, it remains a poor weed competitor throughout its life. Flax does not compete well with weeds because it produces little shade and uses water and soil nutrients less efficiently than most weed species (Gruenhagen & Nalewaja, 1969). Weeds should be controlled when the crop height is between 5 and 10 cm. There are a number of herbicides recommended for efficient control of weed flora in irrigated linseed. Pendimethalin is a selective herbicide effective against most annual grasses and several annual broad-leaved weeds. It is applied as preemergence. Pendimethalin acts via inhibition of microtubule formation, disrupting cell division and causing microfibril disorientation. The study shows that pendimethalin (1.0 kg/ha) applied to different rabi crops persisted in soil up to 75 days after application and afterwards degraded completely, leaving no any toxic residues in post-harvest soil. Mishra et al. (2005) reported that pre-emergence application of squadron 3000 g /ha and sand mix application of pendimethalin 2000 g /ha though completely checked the germination of Cuscuta but proved to be highly phytotoxic to linseed. The maximum seed yield of linseed (1994 Kg) were obtained from Cuscuta free plot followed by preemergence application of pendimethalin 1.0 Kg/ha (1276 Kg), postemergence application of glyphosate at 0.05 kg/ha (1264 Kg) and pendimethalin 1.5 Kg/ha followed by water spray (1183 Kg). Imazethpyr is an imidazolinone compound used as a selective herbicide to regulate most annual grasses and certain broad-leaf weeds. This herbicide is applied as pre-plant incorporated, preemergence and early post emergence for control of annual and perennial grass and broad-leaf. Singh et al. (2014) reported that weed control efficiency (WCE) during 2008 Were highest in two hand weeding’s followed by imazethapyr at 75 g/ha sprayed 15 or 25 DAS and 100 g/ha at 25 DAS. During 2009, two hand weeding’s and imazethapyr at 100 g/ha applied at 15 DAS gave similar WCE, which could flow from to similar dry weight of weeds in these treatments. Weed control efficiency Were lowest in imazethapy