SECTION B
Ques2A. The classification of weed on the basis of common name -
1. Tiger grass - Saccharum spontaneum
2. Guinea grass - Panicum milliceum
3. Soil worst weed - Cyperus
4. devil grass - cynodon dactylon
5. Pig weed - Amaranthus virdis
6. Hog weed - Cannabius sativus
7. Cocklebar - Hanthium spp.
Ques2B Example of sedges and Broad leaf -
Sedges - Cyperus (Motha)
Broad Leaf - Cinopodium album ( Bathua ) , Camellina
Ques2C. Short note of season based weed -
a. Kharif weed - Cyperus rotandus (Motha)
b. Rabi weed - Argemone mixicana , anagallis arvensis , chenopodium album
c. Zaid weeds - include both season weeds
Ques2D.
Ques2E. Cultural weed control involves the use of cultural practices to manage and suppress weed growth. These practices are designed to create an environment that is unfavorable for weed establishment and growth, thereby reducing the competition between weeds and desired crops or plants. Cultural weed control methods are often considered environmentally friendly and are an important component of integrated weed management strategies. Here are some key cultural weed control practices:
1. Crop Rotation:
- Description: Crop rotation involves growing different crops in a specific sequence on the same piece of land over time.
- Benefits: Crop rotation disrupts the life cycle of certain weeds, pests, and diseases. It can also help in improving soil fertility and structure.
2. Cover Cropping:
- Description: Cover crops are planted primarily to cover the soil rather than for harvest. They are grown between main crops or during fallow periods.
- Benefits: Cover crops help suppress weed growth by shading the soil, competing for nutrients, and sometimes releasing allelopathic chemicals that inhibit weed germination.
3. Mulching:
- Description: Mulching involves covering the soil surface around plants with a layer of organic or inorganic material, such as straw, wood chips, or plastic.
- Benefits: Mulch helps in preventing weed germination by blocking sunlight, conserving soil moisture, and improving soil structure. Organic mulches also decompose over time, adding organic matter to the soil.
4. Competition through Crop Density and Arrangement:
- Description: Planting crops at higher densities or in arrangements that reduce the availability of light, nutrients, and space for weeds.
- Benefits: Dense and well-arranged crops can outcompete weeds for resources, limiting weed growth and establishment.
5. Timely Planting and Harvesting:
- Description: Ensuring timely planting of crops to establish a canopy quickly and timely harvesting to prevent weeds from setting seed.
- Benefits: Rapid canopy development shades the soil, inhibiting weed growth. Timely harvesting prevents the weed seeds from entering the soil seed bank.
6. Adjusting Irrigation Practices:
- Description: Managing irrigation to avoid creating favorable conditions for weed growth. For example, using drip irrigation instead of overhead irrigation.
- Benefits: Proper irrigation practices help conserve water, reduce weed germination, and prevent the spread of weed seeds.
7. Tillage Practices:
- Description: Strategic use of tillage to disrupt weed growth and reduce weed seed bank.
- Benefits: Tillage can bury weed seeds, disrupt weed growth, and promote a seedbed that is more favorable for the desired crops.
8. Sanitation:
- Description: Cleaning equipment, clothing, and tools to prevent the unintentional spread of weed seeds.
- Benefits: Minimizing the introduction and spread of weeds in new areas.
Ques2F. A sprayer is a device used to apply liquid substances, such as pesticides, herbicides, fertilizers, or water, to plants or surfaces. Sprayers consist of various parts that work together to deliver and distribute the liquid effectively. Here are the details of some common sprayer parts:
1. Tank:
- Function: The tank holds the liquid solution to be sprayed.
- Materials: Tanks are typically made of plastic, polyethylene, or stainless steel.
2. Pump:
- Function: The pump pressurizes the liquid in the tank, forcing it through the spray nozzle.
- Types: Piston pumps, diaphragm pumps, and centrifugal pumps are common types used in sprayers.
3. Pressure Regulator:
- Function: Maintains a consistent pressure in the system, ensuring a uniform spray pattern.
- Adjustability: Some sprayers have adjustable pressure regulators to control the application rate.
4. Agitation System:
- Function: Keeps the liquid solution well-mixed inside the tank to prevent settling or separation.
- Types: Jet agitation, mechanical agitation, and hydraulic agitation are common agitation systems.
5. Boom:
- Function: A boom is a structural component that supports and positions the spray nozzles at the desired height and spacing.
- Types: Depending on the application, booms can be mounted on the sprayer or towed behind.
6. Nozzles:
- Function: Nozzles create the spray pattern and control the droplet size for effective application.
- Types: Flat fan, cone, flood, and adjustable nozzles are used based on the application requirements.
7. Filters:
- Function: Filters remove debris and particles from the liquid, preventing clogs in the nozzles.
- Types: Strainers, screen filters, and in-line filters are commonly used.
8. Shut-Off Valve:
- Function: Controls the flow of liquid from the tank to the pump and nozzles.
- Types: Ball valves, gate valves, or other types of shut-off valves may be used.
9. Hoses:
- Function: Convey liquid from the tank to the pump and from the pump to the nozzles.
- Materials: Hoses are typically made of rubber, PVC, or reinforced materials.
10. Pressure Gauges:
- Function: Measures the pressure in the system to help operators monitor and adjust the sprayer's performance.
11. Flow Control Valve:
- Function: Regulates the flow rate of liquid through the system.
- Adjustability: Allows operators to control the volume of liquid applied.
12. Strainers:
- Function: Additional filters placed at specific points in the system to catch particles and prevent clogging.
13. Tank Lid and Vent:
- Function: Provides access to the tank for filling and cleaning, and the vent allows air to replace liquid as it is sprayed.
SECTION C
Ques3A. Mode of Action of Herbicide -
The growth regulate herbicides -
eg - 2,4-D, MCBP, Dicamba and Triclopyr
The inhibitor of amino acid synthesis -
eg- Glyphosate , Halosulfuran , Imazethapyr , Sulfameturon.
Cell membrane disruptures -
eg- Oxyfluofen , Lactofen , Acifluron
Lipid biosynthesis inhibitor -
eg - Diclofop, Fluzifop , Clethodium
Pigment Inhibitor
Norflurazon , Fluridone , Amritol
Growth inhibitor of shoot -
Thiocarbamate , EPTC.
Ques3B . Characteristics of weeds -
1. Produce enormous no. of seeds. eg. wild oats (Avena fatua) produces 250 seeds / plant.
2. Thrive well even in adverse condition because they can modify their seed production and growth accordingly to available of moisture and temperature.
3. seeds remain viable for many years without loosing in viability. eg. field bind weeds (Convulvulus arvensis) for about 50 years.
4. weeds seed have tremendous capacity to dispense from on place to another by wind, water , animals and man .
5. weed seeds mimic with the crop seeds due to them size and get transported with them.
6. able to regenerate lost plant.
7. compete with cultivated plants.
8. all seeds of weeds mature simultaneously.
9. weeds have allelopathic effect on crops.
10. produces seeds in flushes.
11. seed production through apomixis, spore , etc.
12. weed seeds have dormancy either inherited or induced .
13. have short period of plant growth.
14. generally grow at faster rate and produce seeds earlier than most of crops growing in association.
Ques4A. Based on Translocation / movement of herbicide in plant -
a. Contact - eg- Paraquat , diquat , propanil , H2SO4 .
Kills either weed or crops when it causes in contact with plant tissues.
Kills pact of plant that is contact.
less mobile.
b. Systemic Translocated - eg- 2,4-D , atrazine , pendamenthalin , glyphosate , dalapon.
Moves within the weed either through xylem or phloem this affect whole system of respiration , and photosynthsis.
Ques4B. Herbicide - Trade name
Propanil - Stam F-34
Quizilofap - assure
Simazine - aquazine
Thiocarb - Boleso
2, 4- D - Plant guard , weedmone
2,4-DP - Butoxone
Ques5A. (a.) Allelopathy refers to the biological phenomenon where one plant species releases chemicals into the environment that affect the growth, development, or germination of other plants. These chemicals are known as allelochemicals, and they can have both inhibitory and stimulatory effects on neighboring plants.
The allelopathic effect involves the production and release of allelochemicals by one plant, which then influences the physiological and biochemical processes of another plant. Allelochemicals can be released into the soil, air, or water and may affect various aspects of plant growth, including:
1. Germination: Allelopathic chemicals can influence the germination of seeds, either promoting or inhibiting the process.
2. Seedling Growth: The growth of seedlings may be affected by allelochemicals, leading to changes in root and shoot development.
3. Nutrient Uptake: Allelopathy can influence the absorption of nutrients by plants, affecting their overall nutrient status.
4. Cell Division and Elongation: The division and elongation of plant cells may be altered, influencing the overall growth and morphology of plants.
5. Microbial Activity: Allelochemicals can impact the activity of soil microorganisms, affecting nutrient cycling and availability.
6. Allelopathic Autotoxicity: Some plants release allelochemicals that can affect their own seedlings, leading to a phenomenon known as allelopathic autotoxicity.
Allelopathy plays a role in plant competition, as plants release these chemicals to gain a competitive advantage over neighboring vegetation. It can occur in natural ecosystems, agricultural fields, and even in home gardens. Some plants are known for their allelopathic properties, actively suppressing the growth of nearby plants. Examples include black walnut (Juglans nigra), which produces juglone, and rye (Secale cereale), which releases allelopathic compounds.
(b.) details of three bio herbicide -
Ques5B. Weeds are generally classified based on their life cycle, growth habit, and ecological characteristics. The classification of weeds helps in understanding their biology and developing effective management strategies.
Here are some common classifications:
1. Life Cycle:
- Annual Weeds: Complete their life cycle within a year. They germinate, grow, flower, set seed, and die within a single growing season.
- Biennial Weeds: Have a two-year life cycle. They typically germinate and form a rosette in the first year, flower and produce seeds in the second year, and then die.
- Perennial Weeds: Live for more than two years. They can persist for many years, reproducing through both seeds and vegetative structures like rhizomes or tubers.
2. Growth Habit:
- Grasses: Weeds that resemble grasses in their growth form and structure.
- Broadleaf Weeds: Weeds with leaves that are broader than grasses. This category includes many common garden and agricultural weeds.
- Sedges: Resemble grasses but have triangular stems.
3. Ecological Characteristics:
- Cultural Weeds: Thrive in disturbed or cultivated areas, often taking advantage of human activities such as agriculture or gardening.
- Invasive Weeds: Non-native plants that aggressively spread and outcompete native vegetation.
- Noxious Weeds: Designated by authorities as harmful and subject to regulatory control due to their impact on agriculture or natural ecosystems.
Reproduction:
Weeds employ various reproductive strategies to ensure their survival and spread:
1. Seed Production: Many weeds reproduce by producing a large number of seeds, which can be dispersed by wind, water, animals, or human activities. The ability of weed seeds to remain viable in the soil for extended periods contributes to their persistence.
2. Vegetative Propagation: Some weeds reproduce asexually through vegetative structures such as rhizomes, stolons, tubers, bulbs, or runners. This enables them to rapidly colonize an area and outcompete other plants.
3. Adaptations: Weeds often exhibit adaptations that enhance their reproductive success. These may include rapid germination, production of allelopathic chemicals (inhibiting the growth of nearby plants), or the ability to withstand adverse environmental conditions.
Dissemination:
Weeds use various methods to spread and establish themselves in new areas:
1. Wind Dispersal: Lightweight seeds equipped with structures like parachutes or wings can be carried by the wind over long distances.
2. Animal Dispersal: Some seeds have adaptations to be carried by animals. This can occur through attachment to fur or feathers, ingestion and subsequent excretion, or adhesion to the exterior of animals.
3. Water Dispersal: Seeds can be dispersed by water, especially in aquatic environments or during periods of heavy rainfall.
4. Human-Mediated Dispersal: Human activities, such as agriculture, construction, and transportation, can unintentionally facilitate the spread of weed seeds. Machinery, vehicles, and contaminated agricultural products can transport seeds over large distances.
Make-Up
Ques5B. Puddling is an important practice in rice cultivation, especially in traditional lowland and irrigated rice fields. Puddling refers to the process of saturating the soil with water and then tilling it to create a dense, impermeable layer in the plow zone. This practice has several important implications for rice cultivation:
1. Weed Control: Puddling helps suppress weed growth by creating a dense, anaerobic (low oxygen) environment in the soil. This reduces the competition between weeds and rice plants for nutrients, water, and sunlight.
2. Water Management: The compacted soil layer formed during puddling helps to retain water in the rice fields. This is crucial in rice cultivation because rice plants thrive in submerged conditions. Puddled soil reduces water seepage, ensuring that the water remains in the fields and is available to the rice plants for a longer duration.
3. Nutrient Availability: Puddling can enhance nutrient availability by reducing the oxidation of soil organic matter. The anaerobic conditions created by puddling slow down microbial activity, preventing the rapid decomposition of organic matter and making nutrients more accessible to rice plants.
Factors Affecting Growth and Development in Rice:
Several factors influence the growth and development of rice plants:
1. Water Management: Rice is a semi-aquatic crop, and water management is crucial for its growth. Proper irrigation, including the timing and amount of water applied, is essential. Puddling helps in water retention and efficient use.
2. Soil Type: The type of soil affects rice growth. Different rice varieties may perform better in specific soil types. Puddling helps create a suitable environment in various soil types.
3. Temperature: Rice is a tropical and subtropical crop, and temperature affects its growth. Warm temperatures are generally favorable, and temperature fluctuations can impact the rice plant's development.
4. Nutrient Management: Adequate and balanced nutrient supply is essential. Puddling can affect nutrient availability by influencing soil conditions, and proper fertilization practices need to be employed.
5. Pest and Disease Management: Pests and diseases can significantly impact rice yield. Integrated pest management and disease control measures are essential for healthy plant growth.
6. Rice Variety: Different rice varieties have specific requirements and characteristics. The selection of suitable varieties for the local environment is crucial for optimal growth and development.
