Legume

1. LEGUMES
By
Hem Chander
Assistant Professor (Botany)
Career Point University Hamirpur (HP) 176041
hemchander78@gmail.com

2. Legume Family - Fabaceae
 All types of beans and peas
 Soybean, peanut, alfalfa, clover
 Also includes various trees such as
 Also includes various trees such as
black locust, redbud
 One of the largest dicot families -
13,000 species
 Ranks right behind grasses in human
impact

3. Family characteristics
 Five-petalled irregular flower with
bilateral symmetry
 Fruit is a legume (dry dehiscent fruit -
 Fruit is a legume (dry dehiscent fruit -
two lines of dehiscence) with one row of
seeds
 Seeds contain two large cotyledons

4. Legume flower
 Irregular flower with
bilateral symmetry
 Often butterfly-
shaped
shaped

6. Legume seeds
 Important food
staple worldwide
 Rich in both oil and
protein
protein
» Higher in protein than
any other food plants
» Close to animal meat
in protein quality
» Often called "poor
man's meat"

7. Legumes and
nitrogen-fixing bacteria
 High protein correlated with root nodules
which contain nitrogen-fixing bacteria
» convert atmospheric nitrogen to useful form
 Because of this legumes enrich the soil
» Farmers often rotate legumes with crops
that deplete soil nitrogen (soybean & corn)
» "Green manure" crops plowed sometimes
» Reduces need for fertilizers - legumes can
be cultivated worldwide - even in poor soils

8. Nitrogen cycle
 Nitrogen
» essential elements for all living organisms
» major component of amino acids, proteins,
» major component of amino acids, proteins,
nucleic acids
 Nitrogen gas (N2) about 79% of the air
» most living organisms cannot use this form
of nitrogen

9. Nitrogen-fixing bacteria
 Certain bacteria and cyanobacteria have
ability to reduce nitrogen (N2) gas to
ammonium NH4
+
ammonium NH4
» cells can convert NH4
+ to compounds
» called nitrogen-fixation
» organisms are called nitrogen-fixing

10. Nitrogen-fixing organisms
 Some bacteria and some cyanobacteria
 Some live freely in the soil
 Most are found in symbiotic associations
 Most are found in symbiotic associations
in the root nodules of legumes
 Azolla is known to have a symbiotic
association with a nitrogen-fixing
cyanobacterium

11. Non-legume plants
 Must rely on the nitrogen compounds
present in the soil
 During decomposition microorganisms
 During decomposition microorganisms
break down proteins and other nitrogen-
containing molecules into ammonium
NH4
+

12. Nitrogen compounds in soil
 Some plants take up ammonium directly
 Bacteria in the soil quickly convert
ammonium to nitrite (NO2) and then
ammonium to nitrite (NO2) and then
nitrate - (NO3)
 Nitrate is the form of nitrogen usually
absorbed by plants
 Fertilizer contain a mixture of both
ammonium and nitrate

13. Nitrogen Cycle
Non-legume
plants
NH4
NO2
NO3
bacteria
bacteria bacteria

14. Other sources of nitrogen
 Burning fossil fuels, volcanic activity,
and lightning combine nitrogen and
oxygen into NO2 and NO3
oxygen into NO2 and NO3
 These are washed into the soil by rain
and contribute to the nitrogen cycle
 Denitrifying bacteria actually break down
ammonium and nitrates returning
nitrogen gas to the atmosphere

15. Legume food crops
 Cultivated for thousands of years in both
the Old World and New World
» seeds easily harvested
» seeds easily harvested
» seeds low water content and easily stored
for long periods of time
 These features plus their high protein
content and ease in growing make them
ideal crops

16. Beans and peas -- Pulses
 Some of the oldest and most common
food crops
 Good source of protein average about
 Good source of protein average about
25% for beans and 21% for peas
 Traditionally cultivated for dry seeds
 Some varieties today have edible pods
 Beans warm season annuals
 Peas grown during the cooler seasons

17. Common Edible Beans & Peas
 Black-eyed peas
 Butter beans
 Chick peas
 Lima beans
 Mung beans
 Navy bean
 Chick peas
 Fava (broad) beans
 Green beans
 Green peas
 Kidney bean
 Lentils
 Navy bean
 Pinto beans
 Snow peas
 Split peas
 Wax bean

18. Other legumes of interest
 Forage plants - alfalfa and clover
 Super tree - Leucaena leucocephala
» tropical tree that is one of the fastest
» tropical tree that is one of the fastest
growing species of woody plants for fire
wood, wood pulp, and enriching the soil
 Beans of the future:
» Winged bean - all parts of plant are edible -
pod, seeds, leaves, flowers, root
» Tepary bean - adapted to arid tropical
areas

19. Summary
 Legumes are second only to the cereals in
their importance in human nutrition and are an
excellent source of high quality protein
Nitrogen fixation is important for generating
 Nitrogen fixation is important for generating
nitrogen compounds that can be used by
plants
 Soybean has been transformed into a variety
of food products and is increasing its role in
the human diet