NCERT Solutions for Class 9 Science Chapter 15

Hybridisation helps to increase the crop production. It involves crossing of inter-variety, inter-specific crossing, inter-generic crossing which give plants of desired characteristics, i.e., high yield of crops which are disease resistant and respond to fertilisers positively, adaptable to the environment, need less water for irrigation and have low maturity periods.

Pasturage is the availability of flowers for nectar and pollen collection for honeybee.
The kind and quality of honey is determined by the kind and quality of pasturage.

Resistant crops variety are useful and give higher yield. Biological control methods are safe, ecofriendly, long lasting and harmless to other forms of life, therefore should be preferred.

The process refers to the transfer of genes from one organism to another, e.g. Bt Cotton is a genetically modified crop which carry bacterial genes, that protects this plant from insects. These are used in rice, maize, brinjal, cabbage, cauliflower to get protection from insects.

Inter-Cropping:
(i) Prevents pests and decreases the chances of spoiling of whole crops, therefore reduce losses and both crops can give better results.
(ii) It can also deal with less monsoon or drought because crop which needs less water can easily survive.
Crop-rotation:
(i) Farmers can grow two or three crops in a year.
(ii) Pulses take nitrogen directly from the atmosphere, and thus needed fewer amounts of fertilisers.
(iii) Vegetables and fruits can be easily grown. It makes best use of land and nutrients present in the soil.

Manure and fertilizers supply nutrients to the soil and increases the fertility of the soil and thus increases the production. They overcome the nutritional deficiency of the soil.

Crop rotation is one of the methods of crop production that ensures high yield. It is the method of growing two or more varieties of crops on the same land in sequential seasons. A crop utilises some particular nutrients in larger quantities from the soil. Then, if the same crop is grown in subsequent seasons those nutrients will get depleted in the soil. Therefore, crops having different nutrient requirements are rotated. For example, legumes which have nitrogen-fixing bacteria in their root nodules supply the soil with nitrogen. Therefore, these legumes are rotated with nitrogen requiring cereals such as wheat and maize. This method reduces the need of fertilizers, thereby increasing the overall yield of crops.

Manures and fertilizers are used in fields to enrich the soil with the required nutrients. Manure helps in enriching the soil with organic matter and nutrients. This improves the fertility and structure of the soil. On the other hand, fertilizers ensure a healthy growth and development in plants. They are a good source of nitrogen, phosphorus, and potassium. To get an optimum yield, it is instructed to use a balanced combination of manures and fertilizers in the soil.

Inter-cropping and crop rotation both play an important role in increasing the yield of crops. Inter-cropping helps in preventing pests and diseases to spread throughout the field. It also increases soil fertility, whereas crop rotation prevents soil depletion, increases soil fertility, and reduces soil erosion. Both these methods reduce the need for fertilizers. It also helps in controlling weeds and controls the growth of pathogens and pests in crops.

Genetic manipulation is a process where the gene for a particular character is introduced inside the chromosome of a cell. When the gene for a particular character is introduced in a plant cell, a transgenic plant is produced. These transgenic plants exhibit characters governed by the newly introduced gene.

Factors responsible for such losses are biotic— insects, rodents, fungi, mites and bacteria, and abiotic— inappropriate moisture and temperatures in the place of storage. These factors cause degradation in quality, loss in weight, poor germinability, discolouration of produce, all leading to poor marketability. These factors can be controlled by proper treatment and by systematic management of warehouses.

Cattle farming is one of the methods of animal husbandry that is most beneficial for farmers. Using this method, better breeds of draught animals can be produced. Such draught animals are engaged in agricultural fields for labour work such as carting, irrigation, tilling, etc.

The common factor for increasing production in poultry, fisheries, and bee keeping is the proper management techniques that are to be followed. Regular cleaning of farms is of utmost importance. Maintenance of temperature and prevention and cure of diseases is also required to increase the number of animals.