Notes
Grade 9 Science: Biology Notes
Ch. 15 Improvement in Food Resources
Facts that Matter
Food supplies proteins, carbohydrates, fats, vitamins and minerals, all of which we require for body
development, growth and health.
Different crops require different climatic conditions, temperature and photoperiods for their growth
and completion of their life cycle. Photoperiods are related to the duration of sunlight. Growth of
plants and flowers are dependent on sunlight.
Successful crop production depends upon many factors such as:
Understanding how crops grow and develop.
Effect of various nutrients, climate, water on the growth of the plant.
Modification and management of each factor for increasing the yield of the crop.
The crops which are grown in rainy season (the kharif season, from June to October) are called as
kharif crops.
Example: Paddy, soybean, pigeon pea, maize, cotton, green gram and black gram are kharif
crops.
The crops which are grown in winter season (the rabi season, from November to April) are called
rabi crops.
Example: Wheat grain, peas, mustard and linseed are rabi crops.
Crop variety improvement: It can be done either by hybridisation or by introducing a gene.
Crop improvement by hybridisation: Hybridisation refers to crossing between genetically
dissimilar plants. This crossing may be intervarietal (between different varieties), interspecific
(between two different species of the same genus) or intergeneric (between different
genera).
Crop improvement by introducing a gene: This provides the desired characteristics and
results in genetically modified crops.
Cultivation practices and crop yield are related to weather, soil quality and availability of
water. Since weather conditions such as drought and flood situations are unpredictable,
varieties that can be grown in diverse climatic conditions are useful.
The factors for which variety of improvement is done are:
Higher yield: To increase the productivity of the crop per acre.
Improved quality: The quality of crop products vary from crop to crop. E.g., the protein
quality is important in pulses, oil quality in oilseeds, preserving quality in fruits and
vegetables.
, Biotic and abiotic resistance: Biotic factors are the diseases, insects and nematodes while
abiotic factors are the drought, salinity, waterlogging, heat, cold and frost which affect the
crop productivity. Varieties resistant to these factors (stresses) can be improved to increase
crop production.
Change in maturity duration: Shorter maturity period of crop reduces the cost of crop
production and makes the variety economical. Uniform maturity makes the harvesting
process easy and reduces losses during harvesting.
Wider adaptability: It allows the crops to be grown under different climatic conditions in
different areas.
Desirable agronomic characteristics: It increases productivity, for example, tallness and
profuse branching are desirable characters for fodder crops; while dwarfness is desired in
cereals, so that less nutrients are consumed by these crops.
Plant nutrients: Nutrients are supplied to plants by air, water and soil. There are sixteen
nutrients which are essential for plants. Air supplies carbon and oxygen; hydrogen comes
from water and soil supplies the other thirteen nutrients to plants. Amongst these thirteen
nutrients, six are required in large quantities and are therefore called macro-nutrients. The
other seven nutrients are used by plants in small quantities and are therefore called micro-
nutrients.
Nutrients supplied by air, water and soil
Manure: Manure contains large quantities of organic matter and also supplies small quantities of nutrients
to the soil. Manure is prepared by the decomposition of animal excreta and plant waste. Manure helps in
enriching soil with nutrients and organic matter and increasing soil fertility. On the basis of the kind of
biological waste used to make manure, it can be classified into three types:
(i) Compost (ii) Vermicompost (iii) Green manure.
(i) Compost: It can be farm waste material such as livestock excreta (cow dung etc.), vegetable
waste, animal refuse, domestic waste, sewage waste, straw, eradicated weeds,etc. This material
is decomposed in pits and this process of decomposition is also called composting. This compost
is rich in organic matter and nutrients.
(ii) Vermicompost: The compost which is made by the decomposition of plant
and animal refuse with the help of redworm is called vermicompost.
(iii) Green manure: Prior to the sowing of the crop seeds, some plants like sun hemp or guar are
grown and then mulched by ploughing them into the soil. These green plants thus turn into green
manure which helps in enriching the soil in nitrogen and phosphorus.
Fertilizers: Fertilizers are commercially produced plant nutrients. Fertilizers supply nitrogen,
phosphorus and potassium. They are used to ensure good vegetative growth (leaves, branches
and flowers), giving rise to healthy plants. Fertilizers are an important factor in the higher yields of
high-cost farming.
Organic farming: It is a farming system with minimal or no use of chemicals as fertilizers, herbicides,
pesticides, etc. and with a maximum input of organic manures, recycled farm-wastes (straw and livestock
excreta), use of bio-agents such as culture of blue-green algae in preparation of biofertilizers, neem leaves
or turmeric specifically in grain storage as bio-pesticides with healthy cropping systems [mixed cropping
inter-cropping and crop rotation]. These cropping systems are beneficial in insect, pest and weed control
besides providing nutrients.
Grade 9 Science: Biology Notes
Ch. 15 Improvement in Food Resources
Facts that Matter
Food supplies proteins, carbohydrates, fats, vitamins and minerals, all of which we require for body
development, growth and health.
Different crops require different climatic conditions, temperature and photoperiods for their growth
and completion of their life cycle. Photoperiods are related to the duration of sunlight. Growth of
plants and flowers are dependent on sunlight.
Successful crop production depends upon many factors such as:
Understanding how crops grow and develop.
Effect of various nutrients, climate, water on the growth of the plant.
Modification and management of each factor for increasing the yield of the crop.
The crops which are grown in rainy season (the kharif season, from June to October) are called as
kharif crops.
Example: Paddy, soybean, pigeon pea, maize, cotton, green gram and black gram are kharif
crops.
The crops which are grown in winter season (the rabi season, from November to April) are called
rabi crops.
Example: Wheat grain, peas, mustard and linseed are rabi crops.
Crop variety improvement: It can be done either by hybridisation or by introducing a gene.
Crop improvement by hybridisation: Hybridisation refers to crossing between genetically
dissimilar plants. This crossing may be intervarietal (between different varieties), interspecific
(between two different species of the same genus) or intergeneric (between different
genera).
Crop improvement by introducing a gene: This provides the desired characteristics and
results in genetically modified crops.
Cultivation practices and crop yield are related to weather, soil quality and availability of
water. Since weather conditions such as drought and flood situations are unpredictable,
varieties that can be grown in diverse climatic conditions are useful.
The factors for which variety of improvement is done are:
Higher yield: To increase the productivity of the crop per acre.
Improved quality: The quality of crop products vary from crop to crop. E.g., the protein
quality is important in pulses, oil quality in oilseeds, preserving quality in fruits and
vegetables.
, Biotic and abiotic resistance: Biotic factors are the diseases, insects and nematodes while
abiotic factors are the drought, salinity, waterlogging, heat, cold and frost which affect the
crop productivity. Varieties resistant to these factors (stresses) can be improved to increase
crop production.
Change in maturity duration: Shorter maturity period of crop reduces the cost of crop
production and makes the variety economical. Uniform maturity makes the harvesting
process easy and reduces losses during harvesting.
Wider adaptability: It allows the crops to be grown under different climatic conditions in
different areas.
Desirable agronomic characteristics: It increases productivity, for example, tallness and
profuse branching are desirable characters for fodder crops; while dwarfness is desired in
cereals, so that less nutrients are consumed by these crops.
Plant nutrients: Nutrients are supplied to plants by air, water and soil. There are sixteen
nutrients which are essential for plants. Air supplies carbon and oxygen; hydrogen comes
from water and soil supplies the other thirteen nutrients to plants. Amongst these thirteen
nutrients, six are required in large quantities and are therefore called macro-nutrients. The
other seven nutrients are used by plants in small quantities and are therefore called micro-
nutrients.
Nutrients supplied by air, water and soil
Manure: Manure contains large quantities of organic matter and also supplies small quantities of nutrients
to the soil. Manure is prepared by the decomposition of animal excreta and plant waste. Manure helps in
enriching soil with nutrients and organic matter and increasing soil fertility. On the basis of the kind of
biological waste used to make manure, it can be classified into three types:
(i) Compost (ii) Vermicompost (iii) Green manure.
(i) Compost: It can be farm waste material such as livestock excreta (cow dung etc.), vegetable
waste, animal refuse, domestic waste, sewage waste, straw, eradicated weeds,etc. This material
is decomposed in pits and this process of decomposition is also called composting. This compost
is rich in organic matter and nutrients.
(ii) Vermicompost: The compost which is made by the decomposition of plant
and animal refuse with the help of redworm is called vermicompost.
(iii) Green manure: Prior to the sowing of the crop seeds, some plants like sun hemp or guar are
grown and then mulched by ploughing them into the soil. These green plants thus turn into green
manure which helps in enriching the soil in nitrogen and phosphorus.
Fertilizers: Fertilizers are commercially produced plant nutrients. Fertilizers supply nitrogen,
phosphorus and potassium. They are used to ensure good vegetative growth (leaves, branches
and flowers), giving rise to healthy plants. Fertilizers are an important factor in the higher yields of
high-cost farming.
Organic farming: It is a farming system with minimal or no use of chemicals as fertilizers, herbicides,
pesticides, etc. and with a maximum input of organic manures, recycled farm-wastes (straw and livestock
excreta), use of bio-agents such as culture of blue-green algae in preparation of biofertilizers, neem leaves
or turmeric specifically in grain storage as bio-pesticides with healthy cropping systems [mixed cropping
inter-cropping and crop rotation]. These cropping systems are beneficial in insect, pest and weed control
besides providing nutrients.
