Biology

• Cereals such as wheat, rice, maize, millets and sorghum provide us carbohydrate for energy requirements.
• Berseem, oats or Sudan grass are examples of fodder crops which are raised as food for livestock.
• Photoperiod - the duration of sunlight required by each plant.
• The kharif season is from the month of June to October (winter). Eg: Paddy, Soyabean, Pigeon pea, Maize, Cotton, Green gram, Black gram.
• Rabi season is from November to April. Eg: wheat, gram, pea, mustard, linseed.
• The major groups of activities for improving crop yields can be classified as:

  • Crop Variety Improvement

  • Crop Production Improvement

  • Crop Protection Management
• 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).
• Another way of improving the crop is by introducing a gene that would provide the desired characteristics. This results in genetically modified crops.
• Factors for crop variety improvement:

  • High Yield: to increase productivity of the crop per acre
  • Improved Quality: baking quality in wheat, protein quality in pulses, oil quality in oilseeds, preserving quality in fruits and vegetables
  • Biotic and Abiotic resistance: varieties resistant to biotic and abiotic stresses can improve crop production
  • Change in Maturity Duration: shorter maturity duration leads to more harvests in a year, uniform maturity makes the harvesting process easy and reduces losses during harvesting
• • Wider Adaptability: crops can be grown under different climatic conditions in different areas
  • Desirable Agronomic Characters: tallness and profuse branching for fodder crops, dwarfness in cereals
• Tallness and profuse branching are desirable for fodder crops because more food is available to the cattle.
• Dwarfness is desired in cereals so that less nutrients are consumed by these crops, and harvesting is easy.
• Biotic factors - diseases, insects, nematodes

  Abiotic factors - drought, salinity, water logging, heat, cold, frost.
• Production practices at different levels - low cost, high cost, no cost
• Nutrients essential for plants- carbon, oxygen, hydrogen, nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, manganese, boron, zinc, copper, molybdenum, chlorine.
• Macronutrients (required in large quantities , supplied by soil)- Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Sulphur
• Macronutrients (required in small quantities, supplied by soil) - iron, manganese, boron, zinc, copper, molybdenum, chlorine.
• Air supplies carbon and oxygen. Water supplies hydrogen and oxygen.
• Deficiency of essential nutrients affect physiological processes (life processes) like reproduction, growth and susceptibility to diseases.
• Manure is prepared by the decomposition of animal excreta and plant waste.
• The process in which farm waste material like livestock excreta, vegetable waste, sewage waste, straw, eradicated weeds, etc. is decomposed in pits is known as composting.
• Vermi compost - earthworms are mixed with compost to hasten decomposition.
• Green manure - plants are grown and mulched into the soul to enrich the soil in nitrogen and phosphorus. Eg: sun hemp, guar
• Organic farming is a farming system with minimal or no use of chemicals.
• Blue green algae are biofertilizers because they can directly fix atmospheric nitrogen.
• Neem leaves or turmeric are used as bio pesticides.
• Irrigation - supply of water at regular intervals.
• Areas with light soil have drought because they have less water retention capacity.
• Dug well - water is collected from water bearing strata.
• Rainwater harvesting and watershed management - two modern techniques for increasing groundwater level.
• Mixed cropping is growing two or more crops with no definite pattern, simultaneously on the same piece of land. It reduces risk and gives insurance against failure of one of the crops. Eg: wheat + gram
• Inter cropping is growing two or more crops simultaneously on the same field in a definite pattern. The crops are selected such that their nutrient requirements are different. It ensures maximum utilisation of nutrients supplied, prevent pests and diseases from spreading to all the plants. Eg: soyabean + Maize
• The growing of different crops on a piece of land in a pre planned succession is known as crop rotation. The availablility of moisture and irrigation facilities decide the choice of the crop to be cultivated after one harvest.
• Most appropriate time for removal of weeds - before fruits and flowers are formed.
• Weed control methods -

  •mechanical removal

  •proper seed bed preparation

  •intercropping, crop rotation

  •summer ploughing
• In summer ploughing, fields are ploughed deep in summers to destroy weeds and pests.
• Abiotic factors affecting storage of grains - inappropriate moisture and temperature
• Biotic factors affecting storage of grains - insects, rodents, fungi, mites and bacteria.
• Improper storage of grains leads to

  •degradation in quality

  •loss in weight

  •poor germinability

  •discolouration
• Steps to take for grain storage :

  •strict cleaning

  •proper drying

  • fumigation