Agricultural Practices and Crop Improvement (Class IX)

Mechanical, cultural, chemical and biological methods are used to control weeds.

Atrazine is a herbicide of the triazine class. Atrazine is used to prevent pre- and postemergence broadleaf weeds in crops such as maize (corn) and sugarcane and on turf, such as golf courses and residential lawns.

Higher yield and desirable agronomic characteristics are two correct reasons from the given options for variety improvement.

Both neem leaves and turmeric are used as bio-pesticides.

All of these are kharif crops.

Shortening the maturity duration of a crop does not affect its resistance towards drought.

Abiotic factors (non-living) – temperature, wind, humidity, rainfall, drought, salinity, water-logging, light intensity, etc.
Biotic factors (living) – pathogens, bacteria, virus, etc.
Drought, salinity and water-logging are categorised under abiotic factors. On the other hand, diseases are caused by biotic factors such as living pathogens, bacteria, virus, fungi, etc. Therefore, diseases are biotic factors affecting crop production.

Ratna is a hybrid variety of rice which has been developed in India.

Organic farming doesn’t include any chemical  fertilizers.

Organic farming excludes or minimizes the use of synthetic fertilizers and pesticides.

This is the correct option as this is not a criterion for the selection of crops for mixed cropping. One component crop should need lesser water than the other component crop.

This is the correct option. Insecticide is any pesticide used to kill, deter or control insects. Weedicide is a chemical agent that destroys unwanted plants, but not wanted ones. Fungicide is a biocidal chemical compound or biological organism used to kill or inhibit fungi or fungal spores.

If adequate reservoirs are available, then canal system is used, in which the main canal, which receives water from one or more reservoirs or from rivers, is divided into branch canals having further distributaries to irrigate fields. However, in areas where canal flow is insufficient or irregular due to inadequate reservoir; the lift system is used. Water is directly drawn from the rivers. Tanks and wells cannot be the answer as they store run-off water or water through seepage.

As more branching increases the bulk of the crop, it ensures good vegetative growth.
(2) and (4) cannot be the answer as dwarfness is not preferred for fodder crops. Dwarf (small) varieties do not have long roots and therefore, receive fewer nutrients as compared to varieties with long roots, which can fetch nutrients from long distances.
(3) is incorrect as little branching will not increase the bulk of the crop.

Weeds are unwanted plants, which grow in gardens, lawns, etc. Weeds are undesirable and some weeds create nuisance because they have thorns and prickles; some release chemicals, which are toxic and cause skin irritation. They are hazardous if eaten. They crowd out and restrict light to desired crops. They also take away the nutrients available for the desired crops in the soil.
Parthenium - “Congress weed”  is a well-known weed.
Cyperus – Weed which mainly grows in slow moving water
Xanthium – It is also a weed belonging to compositae family.
Lentil – Masoor dal is a pulse crop belonging to the legume family. It is consumed as a pulse and is not a weed.
Therefore, lentil is not a weed.