Weeds of wheat and their ecology.pptx

Major weeds of wheat and barley

1. WEEDS OF WHEAT AND BARLEY AND THEIR ECOLOGY Presented by Goma Joshi WS-02M-2023 Weed Science

2. WEED “ Weed is any plant that grows where it is not wanted, especially where man is attempting to grow something else ( Ranjit & Bhattarai, 1988)." They interfere with the production of cultivated crops. They reduce the crop yield either by reducing the amount of harvestable products(grain, stover,forage ) or by reducing the amount of crop actually harvested (Holm, 1971). It has been estimated that globally yield reduction in wheat due to weeds is 13.1% ( Oerke et al., 1994) and 25% to 47% in Nepal ( Manandha et al., 2007). Uncontrolled weed infestation significantly reduces the crop yield between and 15 to 83% in Sorghum, 16 to 94% in pearl millet, and 55 to 61% in finger millet. (Mishra et al., 2018).

3. “Weed ecology” is defined as the study of the interaction or relationship between a weed and another plant and its environment. Weed ecology include weed characteristics and weed classification. Weed characteristics include rapid seed germination, rapid growth, the ability to take up and utilize large amounts of nutrients, prolific seed production, the ability to adapt to various environmental conditions, and high tolerance to stresses. The classification of weeds can be comprised of population dynamic factors (i.e., habitat, growth form, life cycle, reproduction) and seed type. WEED ECOLOGY

4. WEEDS OF WHEAT

5. In Nepal, wheat (triticum aestivum L.) is the principal winter crop. Annual weeds compete most effectively during the seedling stages and early tillering. Weed crop interference causes first a significant reduction in the ear bearing tillers of the crop Under the increasing stress from weeds, the surviving tillers bear shorter ears, lesser number of grains per ear and finally shrievelled grains. Once the crop is covering 50-70% of the soil surface at jointing, it will dominate most newly germinating weeds. Wheat

6. In Nepal, 370 species of wheat weeds representing 54 families and 210 genera of vascular plants were listed. Two most dominant families are Asteraceae and Poaceae which had 69 and 52 weed species respectively. of the 63 major weeds, 53 were reported from hilly regions, 14 from inner terai, and 12 from Terai region of Nepal (Dangol, 2013). The species like Chenopodium album (Bethe), Phalaris minor (Ragate Jhar), Cynadon dactylon (Dubo), Polygonum plebium (Sukulijhar) and Vicia Sativa (Kutilkosa) were mentioned as major weeds. Anagallis arvensis, Crepis japonica, Grangea maderaspatana, Polygonum plebeium were abundant in the research conducted in wheat field of Biratnagar (Niraula, 2013)

7. Broad leaf weed of wheat White goosefoot Chenopodium album Chenopodiaceae Common vetch Vicia Sativa Fabaceae Knot grass Polygonum plebeium Poaceae Wild radish Raphanus raphanistrum Brassicaceae

8. Broad leaf weed of wheat Scarnet pimpernel Anagallis arvensis Primulaceae Black nightshade Solanum nigrum Solanaceae Creeping woodsorrel Oxalis corniculata Oxalidaceae Burr medic Medicago polymorpha Fabaceae

9. Broad leaf weed of wheat Sweet clover Melilotus indicus Fabaceae Black-jack Bidens pilosa Asteraceae Asthama plant Euphorbia hirta Euphorbiaceae Chickweeed Drymaria cordatae Caryophyllaceae

10. Broad leaf weed of wheat Toothed dock Rumex dentatus Polygonaceae Creeping thistle Cirsium arvense Asteraceae Yellow pea Lathyrus aphaca Leguminaceae Cheese weed Malva parviflora Malvaceae

11. Grasses of wheat Common wild oat Avena fatua Poaceae Fineleaf fumitory Fumaria parviflora Fabaceae Scutch grass Cynadon dactylon Poaceae Canary grass Pharis minor Poaceae

12. Sedges of wheat Wheat sedge Carex atherodes Cyperaceae Hoorah grass Fimbristylis miliaceae Cyperaceae Nut grass Cyperus rotundus Cyperaceae Grass like fimbry Fimbristylis umbellarisr Cyperaceae

13. ECOLOGY OF MAJOR WEEDS OF WHEAT

14. An erect, branched (occasionally unbranched) annual herb, green, more or less coated with white mealy pubescence. Many branches may emerge from main tap root system Chenopodium album is the most prevailing weed in the wheat fields (Siddiqui and Bajwa, 2001) leading to significant reduction in grain yield up to 65% (Siddiqui, 2005). It is copious seed-producing proficiency, yielding up to 70,000 seeds per plants. Wheat yield reductions due to C. album competition for 20, 40, 60, 80, and 110 DAE were 12.65, 28.10, 29.11, 31.64, and 32.9 %, respectively. The highest rate of yield decrease was in between 20 and 40 DAE (Mondal et al, 2007) It causes the set back of wheat plants not only because of its competition for nutrients but also due to its competition for light and space. Moreover. the allelopathic effect of C.album to cereals including wheat makes its infestation problem more severe. White goosefoot, Chenopodium album, Chenopodiaceae White goosefoot Chenopodium album Chenopodiaceae

15. A. arvensis is typically a much branched, prostrate, annual herb. It has a fibrous root system, although the generally weak stems can also be ascending or even erect and up to 50 cm tall. A. arvensis requires bare soil for germination, and is therefore only common in disturbed places. Up to 2480 viable seeds have been recorded per square metre of soil after 8 years of cropping and 1 year of pasture in Britain, and in a separate observation seeds have been shown to remain viable in field soils for up to 10 years ( Holm et al, 1977 ). This weed completes with wheat crop in early stage of its growth ( Alam et al., 2001). Scarnet pimpernel, Anagallis arvensis , Primulaceae Scarnet pimpernel Anagallis arvensis Primulaceae

16. R. dentatus is an annual plant Due to its high biomass and superior growth, wheat is more vulnerable to its competition than P. minor (Singh et al., 2013). Allelochemical: root exudates The wheat grain yield loss increased from 1% to 70% with an increase in R. dentatus density from 5 to 30 plants m-2 (Waheed et al., 2017). R. dentatus evolved resistance against metsulfuron-methyl , an ALS inhibitor, due to its continuous use. R. dentatus also exhibited cross-resistance to florasulam, pyroxsulam, iodosulfuron and triasulfuron (Chhokar et al., 2018). . Toothed dock, Rumex dentatus , Polygonaceae Toothed dock Rumex dentatus Polygonaceae

17. Bidens pilosa was also found as a dominant weed species in the winter crop fields . This may be due to a large number of flower heads (80 heads per plant), with high seed production potential (3000 seeds/ year produced by a single plant) ( Mvere , 2004) and capacity to form dense stands (Weber, 2003). Due to high seed production, seed dormancy, seed longevity it possesses higher possibilities of germination and grows into a new plant. Black-jack Bidens pilosa Asteraceae Black-jack, Bidens pilosa ,Asteraceae

18. Convolvulus arvensis , also known as field bindweed, is a drought-tolerant perennial weed It is considered a noxious weed in many agricultural areas, including wheat fields. Field bindweed has a deep and extensive root system, which allows it to compete with crops for water and nutrients. Field bindweed is a highly adaptable plant that can thrive in a wide range of soil types and climates. It reproduces both vegetatively through its creeping roots and by producing seeds The seeds can remain viable in the soil for many years, making it difficult to control. Field bindweed can have a negative impact on wheat fields by reducing crop yields It competes with wheat plants for resources, such as water, nutrients, and sunlight Additionally, the vine-like growth habit of field bindweed can smother wheat plants, further reducing their productivity. Bindweed Convolvulus arvensis Convolvulacceae Bindweed, Convolvulus arvensis , Convolvulacceae

19. Habit: Annual to woody perennial herb, Roots are generally fibrous and stem is generally round, hollow; nodes swollen, solid, produced about 300-460, shiny black, very small, flat seeds. The seeds survive successfully under the anaerobic conditions created by rice culture . The seeds are reported to undergo secondary dormancy under anaerobic conditions. It grows at temperature range of 10-20°C (Bhan & Chaudary, 1976). Phalaris minor dispersed their caryopses by shattering from their glumes, Canary grass, Pharis minor ,Poaceae Canary grass, Pharis minor ,Poaceae

20. Phalaris minor mimics with the wheat crop in initial growth stages morphologically. Phalaris minor has almost similar maturity time with wheat crops and as a result, they are harvested along with crop and contaminate wheat grains. They are sown again with wheat in the next year, P.minor also shows biochemical mimicry. Eg : minor resistance to fenoxaprop-P-ethyl is first case of herbicide resistance in Pakistan. 40-60% reduction in wheat field with P.minor of 108-915 plants per square meter. Canary grass, Pharis minor ,Poaceae Canary grass Pharis minor Poaceae

21. It is an annual grass , also called satellite weed. It is difficult to eradicate because the seeds shatter before crop maturation and many of the seeds are plowed into the soil, where they lie dormant for one to many years, and germinate when they are turned up near the surface. Opening autumn rains encourage germination of 40% of wild oat seeds, with a further 10-30% germinating later during the season. Wild oats avoid early herbicide applications as a proportion of the seeds germinate later than the crop. They produce a large number of seeds and up to 20 000 seeds/m2. A. fatua interference with wheat reduced light penetration and leaf area of wheat crop. It possess a root system that is more extensive than that of wheat which helps them to absorb water more efficiently under water stress conditions (McLellan, 2015) Wild oats act as a host for a number of important cereal diseases including cereal cyst nematode, stem nematode, rhizoctonia, crown rot and root lesion nematode . Wild oats are highly competitive and when left uncontrolled can reduce wheat yields by up to 80%. Common wild oat, Avena fatua , Poaceae Common wild oat Avena fatua Poaceae

22. C. dactylon is a stoloniferous grass widely naturalized in tropical and subtropical regions of the world. This species is a C4 grass included in the Global Compendium of Weeds (Randall, 2012) . It is listed as one of the most “serious” agricultural and environmental weeds in the world (Holm et al., 1977). It is a fast-growing grass that spreads by seeds and stolons and rapidly colonizes new areas and grows forming dense mats. C. dactylon is very drought tolerant by virtue of rhizome survival through drought-induced dormancy over periods of up to 7 months. After dormancy, it has the ability to easily re-sprout from stolons and rooted runners. Plants also recover quickly after fire and can tolerate at least several weeks of deep flooding (Cook et al., 2005). Quack grass Cynadon dactylon Poaceae Quack grass, Cynadon dactylon , Poaceae

23. It is a perennial sedge, which multiplies rapidly through extensive network of under-ground tubers having strong apical dominance. Single tuber may give rise to more than 100 tubers in 3 month. Its success in dominating natural habitats depends on its ability to prevent herbivory, and to kill or suppress other plants growing in its vicinity Approximately 95% of purple nutsedge tubers are confined to the top 12 cm of soil (Siriwardana and Nishimoto 1987, Methanolic extract of tubers of nutgrass strongly inhibited activity of AChE from electric eel, wheat and tomato. It also inhibited seed germination and seedling growth in wheat. Nut grass Cyperus rotundus Cyperaceae Nut grass, Cyperus rotundus , Cyperaceae

24. WEEDS OF BARLEY

25. In Nepal, Barley is the fifth most important cereal crop with an average productivity of 1.25t/ha . The critical period for weed control is 23 and 48 days after seedling emergence. Weed crop interference causes first a significant reduction in the ear bearing tillers of the crop. Under the increasing stress from weeds, the surviving tillers bear shorter ears, lesser number of grains per ear and finally shrievelled grains. Weed compete with crops for essential resources resulting in lower productivity. Barley

26. Broad leaf weed of Barley White goosefoot Chenopodium album Chenopodiaceae Nettle-leaved goose foot Chenopodum murale Chenopodiaceae Knot weed Persicaria nepalensis Polygonaceae Wild Radish Raphanus raphanistrum Brassicaceae

27. Broad leaf weed of barley Sweet clover Melilotus indicus Fabaceae Black-jack Bidens pilosa Asteraceae False cleavers Galium spurium Rubiaceae Stickwort Spergula arvensis Caryophyllaceae

28. Broad leaf weed of Barley Toothed dock Rumex dentatus Polygonaceae Creeping thistle Cirsium arvense Asteraceae Yellow pea Lathyrus aphaca Leguminaceae Cheese weed Malva parviflora Malvaceae

29. Broad leaf weed of barley Morning glory Ipomoea purpurea Convolvulaceae Bindweed Convolvulus arvensis Convolvulacceae Creeping woodsorrel Oxalis corniculata Oxalidaceae Burr medic Medicago polymorpha Fabaceae

30. Grasses of Barley Common wild Oat Avena fatua Poaceae Canary grass Phalaris brachystachys Poaceae Scutch grass Cynadon dactylon Poaceae Animated Oat Avena sterilis Poaceae

31. Grasses of Barley Rigid rye grass Lolium rigidum Poaceae Annual blue grass Poa annua Poaceae Yellow foxtail Setaria Pumila Poaceae Crab grass Digitaria ternata Poaceae

32. ECOLOGY OF MAJOR WEEDS OF BARLEY

33. Wild radish is an annual or biennial weed . Wild radish is highly adaptable and can grow in various habitats . It is often found in temperate and Mediterranean regions. It competes with barley for essential resources such as water, nutrients, and sunlight. Its rapid growth and dense foliage can shade the barley plants, reducing their photosynthetic capacity and impeding their growth and development. Wild radish has been found to release allelochemicals, such as glucosinolates, which can inhibit the growth of neighboring plants. Wild radish produces a large number of seeds that are easily dispersed by wind, machinery, animals, and water. These seeds can remain viable in the soil for several years, forming a persistent seed bank. This seed bank allows for the re-infestation of wild radish in subsequent barley crops, making it a challenging weed to manage over time. In recent years, wild radish populations have developed resistance to several herbicides commonly used in barley cultivation. Wild Radish Raphanus raphanistrum Brassicaceae Wild Radish, Raphanus raphanistrum ,Brassicaceae

34. Persicaria nepalensis is a herbaceous perennial plant. Its vigorous growth and dense foliage can shade the barley plants, leading to reduced photosynthesis and stunted growth. As a vigorous and invasive plant, Persicaria nepalensis can modify the physical structure of the habitat it occupies. It forms dense stands and can crowd out native vegetation, altering the biodiversity and ecological balance of the ecosystem. Persicaria nepalensis can reproduce through both seeds and vegetative propagation. It produces numerous small seeds that can be dispersed by wind, water, animals, or human activities. These seeds have the potential to persist in the soil and remain viable for several years, allowing for long-term infestation and re-establishment of the weed in barley fields. Knot weed Persicaria nepalensis Polygonaceae Knot weed, Persicaria nepalensis , Polygonaceae

35. Wild oat is an annual grass weed that is widely distributed in temperate regions. Wild oat is a highly competitive weed species that can significantly reduce barley yields if left uncontrolled. It competes with barley for essential resources like sunlight, water, and nutrients. The fast growth and dense canopy of wild oat can shade the barley plants, reducing their access to sunlight and inhibiting their growth and development. Allelopathy: Wild oat has been found to release allelochemicals, such as benzoxazinoids, into the soil. Seed Dispersal and Persistence: Wild oat produces a large number of seeds that are easily dispersed by wind, machinery, animals, and water. These seeds can remain viable in the soil for several years, forming a persistent seed bank. This makes wild oat a persistent and difficult-to-control weed in barley fields, as new seedlings can emerge over multiple growing seasons Common wild Oat Avena fatua Poaceae Common wild Oat, Avena fatua , Poaceae

36. Bromus sterilis is an annual grass, completing its life cycle within a single growing season. It germinates from seeds in the spring, grows rapidly, flowers, produces seeds, and then dies off in late summer or early autumn. Sterile brome seeds have the ability to remain dormant in the soil for several years, forming a persistent seedbank It has the ability to rapidly establish and grow, often outcompeting the desired crop for resources such as water, nutrients, and light. This grassy weed has an upright growth habit, similar to barley. Its stems can reach heights of up to 3 feet, forming dense clumps within the barley field. Allelopathy: Sterile brome has been reported to possess allelopathic properties. It competes for resources and can overshadow the crop, leading to decreased light interception, nutrient uptake, and water availability for barley plants. Sterile brome is a prolific seed producer. A single plant can produce up to 200 seeds, which contribute to the persistent seedbank in the soil. This makes it challenging to control, as new seedlings can emerge in subsequent growing seasons. Sterile brome Bromus sterilis Poaceae Sterile brome, Bromus sterilis, Poaceae

37. Eleusine indica is a warm-season annual grass that thrives in tropical and subtropical regions. Eleusine indica has a prostrate growth habit, with stems that can reach up to 60 centimeters in length. Its leaves are narrow and have a prominent midrib. It is a C4 plant, which means it has a specialized photosynthetic pathway that allows it to efficiently capture and use carbon dioxide. This gives it a competitive advantage over many other plants, especially in high light and high temperature conditions. It can compete with barley for resources such as water, nutrients, and light, potentially reducing barley yields. Additionally, it can produce a large number of seeds, which can contribute to its persistence and spread in the field. Goose grass Eleusine indica Poaceae Goose grass, Eleusine indica ,Poaceae

38. Echinochloa crusgalli , It is an annual grass weed that competes with barley for resources such as water, nutrients, and sunlight. Echinochloa crusgalli is a C4 plant, meaning it has a more efficient photosynthetic pathway compared to barley, which is a C3 plant. It is also a prolific seed producer, with each plant capable of producing thousands of seeds that can remain viable in the soil for several years. The seeds are dispersed by wind, water, and animals, further contributing to its ability to colonize new areas. It has a rapid growth rate and can quickly colonize an area if left unchecked. It can tolerate both flooded and dry conditions, making it a successful competitor in many ecosystems. Cockspur grass Echinochloa crusgalli Poaceae Cockspur grass, Echinochloa crusgalli ,Poaceae

39. Setaria viridis is an annual grass It germinates from seeds in the spring or early summer and grows throughout the warm months until it produces seeds, typically in late summer or early autumn. The mature seeds drop to the ground, and the cycle begins anew the following year. Se eds have the ability to remain dormant in the soil for several years, forming a seed bank. The seeds germinate in response to favorable conditions, such as adequate moisture and temperature. It can be highly competitive with barley for resources like water, nutrients, and sunlight. In dense infestations, Setaria may outcompete young barley plants, reducing their growth and overall yield. It produces large numbers of seeds per plant, enhancing its ability to spread and establish new populations. These seeds have bristles that aid in wind dispersal, enabling them to travel over considerable distances. Green foxtail Setaria viridis Poaceae Green foxtail, Setaria viridis ,Poaceae

40. Dangol, Dharma. (2013). Weeds of Wheat in Nepal: A Literature Review. Journal of Natural History Museum (Nepal). J. Nat. Hist. Mus.. 132-178. 10.3126/jnhm.v27i0.14161. Mishra, J. S. and Kumar, Rakesh and Upadhyay, Pravin and Hans, Hansraj. (2018). Weed management in millets. 68: 77-79 Ranjit, J. D, (2008). Common weeds of rice and wheat. Nepal Agricultural Research Council, Agronomy DivisionS. Manandhar, B.B. Shrestha &H. D. Lekhak. (2007). Weeds of paddy field at kirtipur, kathmandu. Scientific World 5(5) References

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