Eichhornia crassipes (water hyacinth) is the world's most problematic aquatic weed, also called "Terror of Bengal". Because of its very high rate of growth, it can cover the surface of whole water bodies, choke them and cause a threat to other aquatic life forms.

Prey species have evolved various defenses to lessen the impact depredation. For pant, herbivores are the predators plants have evolved an astonishing verity of morphological and chemical defense against herbivores. Calotropis produces highly see any cattle or goat browsing on this plant. A wide variety of chemical substance that we extract from plants on a commercial scale (nicotine, caffeine, quinine, strychnine, opium, etc.) are produced by them actually as defenses against grazers and browsers. So, the correct answer is 'The plant produces cardiac glycosides'.

Native to South America, Lantana camara was brought to India by the British as ornamental plants, possibly as long as 200 years ago. Forest officials in different parts of the country have watched helplessly as the invasive plant has spread, and efforts to contain it have gone largely in vain.

Weeds can be defined as the unwanted plants that grow in the field and harm the desired crops. Parthenium is the flowering plant which can cause an allergy is the most important weed of corn and wheat field. Xanthium is the ruderal weed of maize. Cyperinus is the most invasive weed found throughout the world. It is the weed of rice field. 

Weeds are the unwanted or undesirable plants as they compete with desirable crops in the field for nutrients, sunlight and interfere with the growth of crops.

Herbicides are chemical which control weeds. These are also called as weedicides. Glufosinate ammonium is a broad spectrum herbicides. A 2,4-D (2,4-Dichlorophenoxyacetic acid) is a plant hormone that acts as herbicide. It kills the broadleaf weeds that harm the plants by causing uncontrolled growth in them.

Removal of weed (or weeding) is done before weeds flower because if they flower they will also produce seeds and finally result in the dispersal of the seeds which makes it difficult to control the weeds because each seed will produce a new weed plant.

A weed is a wild plant that grows in an unwanted region and is a competition to cultivated plants. They are also known as invasive plants. Weeds typically produce a large number of seeds and propagate enormously. They are highly competitive, persistent, pernicious and may interfere negatively with human activities. It may have good properties also. But the undesirable properties outweigh the desirable properties at a given place. 

Auxins have a cardinal role in the coordination of many growths and behavioral processes in the plant's life cycle and are essential for plant body development. So the correct option is ' Auxin'.

Weeds are unwanted plants which grow along with the crop plants in the cultivated field. Some common weeds in India are Amaranthus (Chaulai), Parthenium (Gajar ghas), Cyperus rotundus (Motha), Chenopodium (Bathua), Xanthium (Gokhroo). Weeds compete with the crop plants for nutrients, space, light and water. This results in lowering the food grain quality and reduction in crop yield. Weeds may produce toxic substances which may interfere with crop growth. During harvesting, weeds get mixed up with crops to lower down its quality.

So, the correct answer is 'Weeds'.

The growth of weeds can be controlled by the following methods:

Weeding is necessary since weeds compete with the crop plants for water, nutrients, space and light. Thus, they affect the growth of the crop. Some weeds interfere even in harvesting and may be poisonous for animals and human beings. 

Any plant not sown in the field by the farmer and grow where it is not wanted is called a weed. 

• A weed can be defined as any plant that requires some form of action to reduce its effect on the economy, the environment, human health, and amenity. 
• Weeds compete with crops for space, nutrients, water, and light. Smaller, slower-growing seedlings are more susceptible than those that are larger and more vigorous. 

Weeds are the undesirable plants that are not cultivated. They are the plants at the wrong place. They compete with the crop for nutrients and space. Hence, they are harmful to the crop. These weeds can be controlled by using weedicides.

The unwanted plants which grow in field along with the crop plants are termed as weed. They are harmful for the crops as they compete for nutrients with them.

Insecticides and pesticides are used to kill the insects and the pest that harm the crops . While biofetilizers are the manure (contains living microorganisms) . On the other hand , weedicides are used to kill the weeds .

The unwanted plants in a crop field are known as weeds. These compete with the crop plants in the field for nutrition, hence hampering their growth. 

Malathion is an organophosphate and an acetyl cholinestrase inhibitor that is strictly used as a topical pediculicide.

Eichhornia crassipes , commonly known as water hyacinth , is an aquatic plant native to Amazon basin, known for it's highly problematic invasion outside it's native range. It forms dense mats in the water bodies, which causes the reduction in the oxygen for other organisms in the water body .

Weeds can be defined as the unwanted plants that are grown in the field and harm the desired crops. Cyperinus is the most invasive weed found throughout the world. It is the weed of rice field. This is the weed which is commonly found in the temperate regions. 

When the invasive species prickly pear was introduced it possessed a threat to the native species. The growth Opuntia is then controlled by the introduction of the species of the cochineal insect.

A carbamate is an organic compound which is derived from carbamic acid (NH$ _{2}$COOH). 

Weeds are unwanted plants in the cultivated field. They compete with the crop plants for food, space and light. They take up the nutrients and reduce the growth of the  crop.

Parthenium is most common weed which grows anywhere on the land like roadsides, war footings etc.  It releases chemicals to supress the growth of plants and allergents toxic to other livestock. Thus it is important to supress  this weed first. Thus the correct answer is 'Parthenium'. 

Eichhornia crassipes also known with the common name of water hyacinth is a free-floating aquatic plant native to America. It is often considered a highly problematic invasive species outside its native range. E. crassipes reproduces both vegetatively and sexually, but the vegetative reproduction is responsible for the plant’s rapid spread and colonization of water bodies. It occurs through the formation of stolons, which produce daughter plants. This is generally very rapid, if the temperature is high and nutrients are available, it often invades bodies of water that have been impacted by human activities as they often receive large amounts of nutrients. One plant can multiply to cover one acre in a single growing season forming a dense strand. So, with the combination of its free-floating habit, rapid vegetative propagation, and ability to survive on mud during periods of low water levels, E. crassipes has been able to naturalize in a wide variety of aquatic habitats.

Weeds are nothing but unwanted crops that grow along with the main crop. Thus, they compete with the main crop for sunlight, water, nutrients, and space and thus reduce the resources available to them. In this way, they hamper the growth of the main crop.

• Rotating crops with ones that kill weeds by choking them out, such as hemp and other crops, can be a very effective method of weed control. 
• It is a way to avoid the use of herbicides and to gain the benefits of crop rotation. 

The unwanted plants which grow in field along with the crop plants are termed as weed. They are harmful for the crops as they compete for nutrients, space and sunlight with them.

The unwanted plants which grow in field along with the crop plants are termed as weed. They are harmful for the crops as they compete for nutrients with them.

The  Eichhornia , commonly known as common water hyacinth, is an aquatic plant native to the Amazon basin, and is often a highly problematic invasive species outside its native range . It grows at an alarming rate and spreads on the surface of the water body. This cut out of the light and it also causes an increase in the oxygen demand. Thus, causing the death of fishes and other aquatic organisms. 

Congress grass is the common name for Parthenium hysterophorus . It is a species of flowering plant in the aster family, Asteraceae. 

Parthenium hysterophorus is commonly called as congress grass or gajar ghass .It is a species of flowering plant in the aster family, Asteraceae. It is native to the American tropics. This weed is equally dangerous for all flora and fauna. It is highly dangerous for humans. It utilizes most of  the nutritious substances from soils, thus converting fertile ground into unfertile ones.

• Agent Orange refers to a herbicide mixture which was used by the U.S. military during the Vietnam War and it contained a dangerous chemical contaminant called dioxin. 
• The active ingredient of Agent Orange was an equal mixture of two phenoxy herbicides – 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5 trichlorophenoxyacetic acid (2,4,5-T) and it also contained traces of the dioxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).
  
• So the correct option is ' All of the above'.

Silviculture is the process of controlling the growth, composition, health, and quality of the forests to satisfy people's diverse needs and values.

Sacred groves are one of the methods of conserving rare and threatened species as local people worship and not allow the killing of animals and cutting of trees in such areas like Khasi and Jaintia Hills in Meghalaya, Aravalli Hills in Rajasthan etc.

The Amrita Devi Bishori National award is awarded for wildlife conservation.

Afforestation restores ecological balance of all ecosystems, it maintains biological diversity, and act as catchments for soil and water. Thus preventing floods  and conserving soil cover.

Forest conservation is the practice of planning and conserving forests for the sustainability of future generations. Deforestation is the clearing of trees and thereby transforming a forest into cleared land. It results in the loss of habitat for millions of species. Global warming is condition in which there is increase in the earth's surface temperature due to effect of greenhouses gases which are released due to burning of soil, deforestation, etc. Afforestation is the establishment of a forest in an area either naturally or artificially where there was no forest previously. 

Forests not only provide wood but they directly control floods, drought, soil erosion etc. Forest conservation is very important to maintain a balanced ecosystem. It involves preservation and management of forests and wildlife. Conservation of forests can be done by maintaining biosphere reserves, wildlife sanctuaries, national parks, zoo and botanical gardens.

Forest conservation is the practice of planning and conserving forest areas for the benefit of future generations. Afforestation is the establishment of a forest in an area either naturally or artificially where there was no forest previously. It is done to keep the natural resources intact for the maintenance of ecosystem and benefit of human. Different techniques done for forest conservation are afforestation, reforestation, controlled burn, etc. 

Agroforestry is the land use pattern or pathway that allows the combination of agriculture and forestry. It is a land management system. Shifting cultivation includes the use of land for agricultural purpose followed by clearing off of the cultivation and leaving the pasture undisturbed to restore its fertility. Shifting cultivation is associated with agroforestry.

A) Weeds are removed with the help of a harrow. It also helps in loosening the soil so that the water can soak into the ground easily.

Forest have been called the 'lungs of earth' because growing trees take carbon dioxide out of the air and replace it with oxygen. This is vital for humans, as we need oxygen in the air to breathe. As lungs take out the carbon dioxide from the body and supply oxygen to all parts of our body via nerves. Similarly forests also absorbs carbon dioxide from the surroundings and extract the oxygen from the trees.

• A forest is a large area dominated by trees. Forests are the dominant terrestrial ecosystem of Earth, and are distributed around the globe. Forests account for 75% of the gross primary production of the Earth's biosphere, and contain 80% of the Earth's plant biomass.
  
• Forest helps in controlling the flow of water and slows it down which helps in preventing flood. Also, the trees present in the forest prevents the rain from directly hitting the ground and bind the soil together which helps in absorption of the rain water and thus prevent flood.
  
• Trees also prevent soil erosion.

The International Rice Research Institute (IRRI) is an international agricultural research and training organization with headquarters in Los Baños, Laguna in the Philippines and offices in seventeen countries. The Central Rice Research Institute is located in Cuttack. It is Asia's largest Rice Research Institute.