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WELCOM
E
TOPIC:
CLASSIFICATION OF WEEDS
SUBMITTED TO:Dr . Shankarnarayan sirDepartment of AgronomySericulture college Chintamani
Submitted by:Anil Kumar. G.NI BSc (Agri)ID.No: ALC3004Sericulture College Chintamani
CONTENTS: INTRODUCTION. DEFINATION OF WEEDS. CLASSIFICATION OF WEEDS.
INTRODUCTION: 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.
CLASSIFICATION OFWEEDS:
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.
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.
Aquatic weeds
Terrestrial weeds
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.
Classification according to cotyledon. According to cotyledons weeds are classified
as monocotyledon or dicotyledon species. The monocots are narrow leaved weeds of
grass family , dicots are broad leaved.
Classification according to bark tissue.
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.
Classification according to association with crops
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 .
Classification according to relative position of weeds
These may be absolute weeds , relative weeds, rogues .
Rogues means mixture of other variety in a variety grown.
Classification according to parasitization.
Some weeds grow as parasites on other crops.
They may be considered as loaders. These are cuscuta , orobanchae , striga,
etc.