Classification of weeds.
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This document discusses the classification of weeds. It defines weeds as plants that interfere with human activities or welfare. Weeds can be classified according to their habitat as aquatic, terrestrial, or subterranean. They can also be classified based on their life cycle as annual, biennial, or perennial. Additionally, weeds are classified as monocotyledons or dicotyledons. Lastly, the document discusses classifying weeds according to their association with certain crops.
Classification of weeds.
- 3. SUBMITTED TO: Dr . Shankarnarayan sir Department of Agronomy Sericulture college Chintamani Submitted by: Anil Kumar. G.N I BSc (Agri) ID.No: ALC3004 Sericulture College Chintamani
- 4. INTRODUCTION. DEFINATION OF WEEDS. CLASSIFICATION OF WEEDS.
- 5. The definition of weeds is predicated on human perception , desire and needs. A weed is a plant which interferes with human activity or welfare. It is also defined as plant growing in a place where it is not desired at a particular point in time.
- 6. Classification according to habitat. weeds occur in crop lands , orchards , forests. They may be aquatic , terrestrial and subterranean. Aquatic: These weeds grows in water. Ex: masilea guadrifolia, and some convolvulaceous plants are water hyacinth, hydrilla, algae, reed grass etc.
- 7. Terrestrial: All mesophytic weeds. Roots of these weeds remain concentrated in 20-30 cm depth from surface. Subterranean: These weeds are not fully subterranean , their roots , rhizomes , remain underground and multiply.
- 9. Classification according to life cycle. These may be annual , biennial or perennial. Annuals : They may mostly complete their life cycle in a season. Biennials : These weeds complete their life cycle in 2 seasons/years. Perennials: These weeds are found almost every where in cultivated lands , uncultivated lands , waste lands.
- 10. According to cotyledons weeds are classified as monocotyledon or dicotyledon species. The monocots are narrow leaved weeds of grass family , dicots are broad leaved.
- 11. On this basis weeds may be woody , semi woody , and herbaceous. Herbaceous weeds are more common than others. Ex : lantana camara, acacia arabica, are common woody species.
- 12. Weeds flora and their characteristics are different in different types of crops . some may be common. According to their association they may be upland rice association weeds , low land rice association weeds , wheat association weeds, pulse association weeds. Etc Ex: In mustard-cleome viscosa and cleome menaphylla. In horse gram- tephrosia purpurea. In rice- O.sativavar fatua .
- 13. These may be absolute weeds , relative weeds, rogues . Rogues means mixture of other variety in a variety grown.
- 14. Some weeds grow as parasites on other crops. They may be considered as loaders. These are cuscuta , orobanchae , striga, etc.