Agronomy — Part 2 MCQs with Explanations

Stem borer is one of the most common pests of rice. It can cause severe destruction to the field as it infects the central tiller of the plant leading to drying during the vegetative stage. In grown-up plants, whole ear heads become dried and yield chaffy grains which are also called "White Ear" . While in the vegetative stage larva enters the stem and feeds on the growing shoot and causes drying of the central shoot known as "dead heart” .

As per many botanists, it is believed that the soybean was first domesticated in central China as early as 7000 BCE. It is a quite ancient crop, that was being cultivated in China, Japan, and Korea for thousands of years. Because of its rich nutrient value, it is widely used in the food industry as well medical sciences also.

As groundnut belongs to the legume family, it is rich in protein and oil content. It is a very nutritious seed that includes 45% oil and 22 - 30% protein along with other minerals and vitamins.

RGR is the Relative Growth Rate. NAR is the Net assimilation Rate. LAI is the Leaf area Index. Thus, the relative growth rate depends on both the net assimilation rate as well as leaf area index. Light falling on the leaf and absorbed depends on the availability per unit area further influencing the rate of photosynthesis and assimilation ultimately the growth rate of the plant.

Sugarcane is the commercial crop of tropical countries and can be grown in both tropical as well as subtropical climate. While the best suited temperature for the growth of sugarcane is from 21° to 27° and annual rainfall is between 75 cm to 100 cm.

Soil organic carbon is a measurable component of soil organic matter. Organic matter makes up just 2 - 10% of most soil's mass based on composition. While carbon is the main constituent of organic matter and it plays important role in enhancing the fertility, water retention capacity and texture of the soil. Approximately 0.51% of carbon in organic matter can be considered as medium availability.

The optimum seed rate of castor plantations is approximately 18 - 20 kg/hectare for the desired population. Plant population and arrangement in the cropping system should be properly designed to maximize the seed yield of short height genotypes of castor.

The Law of optima or the law of limiting factors has been proposed by Blackman in 1905. This law comes into effect when any biochemical process in any organism is affected by several factors. This law states that if a chemical process is affected by more than one factor, then its rate will be determined by the factor which is nearest to its minimal value.

Topping and desuckering is a practice widely used on a tobacco plantation. The main aim of this practice is to divert the energy and nutrients from flowers to the leaves, to increase the leaf size and its quality because tobacco yield is dependent on leaf quality and quantity.

Dolma is the husk with less variety of barley. This variety is quite suitable to be grown in rain-fed and hilly areas of Himachal Pradesh and Uttarakhand. It is fairly resistant to yellow rust. Its life cycle is 140 - 150 days.

Pure air i.e. atmosphere is composed of nitrogen - 78%, oxygen - 21%, carbondioxide - 0.033% and traces of some other gases like argon, helium, ozone, neon, etc.

A seed workboard is required for the blending of seeds. This board of seed analyses the seed samples physically with maximum efficiency. One more board is the seed purity board also functions to check the purity of seeds in the laboratory.

Sugarbeet ( Beta vulgaris ) is a species of flowering plant belonging to the family Amaranthaceae or Chenopodiaceae . It is an herbaceous plant with edible roots. Sugar beet juice contains high levels of sucrose and is second only to sugarcane as a major source of the world's sugar.

Most enzyme needs some elements as co-factor or activator to get themselves activated, likewise, urease enzyme also needs Nickel as a cofactor to start functioning. Urease is the enzyme that digests urea and hydrolyses it into simpler compounds.

Stripe rust of wheat is one of the types of rust disease in wheat crops. It is also called wheat yellow rust. It can cause significant loss to crop yield and its quality. In this disease elongated lesions are present on the infected area which bears yellow-orange spores, that is why it is called yellow rust.

The concentration of carbon dioxide in the earth's atmosphere is currently at nearly 400 - 500 parts per million (ppm). And because of the extreme rise in temperature because of global warming and pollution, the concentration of CO 2 keeps on rising.

The concentration of carbon dioxide in the earth's atmosphere is currently 421 parts per million (ppm) in the May 2022. And because of the extreme rise in temperature because of global warming and pollution, the concentration of CO 2 keeps on rising.

The relationship between two organisms where one organism is benefitted while the other one is neutral neither benefitted nor harmed, that type of relationship is known as commensalism . While the mutual relationship where both the organism is benefitted is termed symbiosis .

The triple response is the condition in plants that is triggered by the use of ethylene. It causes plants to have short roots, fat shoots, and increased lateral root growth, morphologically changes can be defined as inhibited root elongation, enhanced radial swelling and shortening of the hypocotyl.

Methane is the major constituent of biogas generated from cow dung. It contains approximately 75% of methane gas and 25% of carbon dioxide, some other gases like hydrogen, hydrogen sulphide, water vapour, nitrogen, oxygen and ammonia.

The area that corresponds to the total sown area is termed the area under cultivation. And the total cultivated area in India was approximately 155.2 million hectares as per the survey held in the fiscal year 2015, which is now increased to 180 mha.

The condition of extensive interveinal chlorosis of older leaves which later infects the younger leaves is due to a deficiency of magnesium. Sometimes it causes reddish brown tints and early leaf fall. Magnesium deficiency is common in tomatoes, apples, grapevines, raspberries, roses and rhododendrons.

Ginning is the process of transforming cotton from field to fabric while ginning percentage is calculated mathematically through a formula: $${\text{GP}}\% = \frac{{{\text{Weight of link}}}}{{{\text{Weight of seed cotton}}}} \times 100$$ Out turn of lint to seed is expressed as a percentage by weight and it normally varies between 24% - 38%.

Different variety of the same category is nitrogen-fixing bacteria also called Rhizobium is responsible for fixing atmospheric nitrogen in different leguminous plants. The bacteria responsible for nitrogen fixation in soybean is R. japonicum . It forms a symbiotic relationship with host plants.

The inherent capacity of soil to supply plant nutrients in adequate amounts and suitable proportions is called Soil fertility. It can also be defined as the capability of the soil to provide all the essential nutrients in all available forms to the plant.

Groundnut has a unique ability to embed fertilized ovary of the flower into the ground through a specialized organ known as peg or gynopore . This peg is a tube-like structure formed after successful fertilization in flowers which is further developed into fruits.

UPAS 120 is an early maturing variety of pigeonpea that takes approximately 120 days to mature. It is a mutant variety that is in use since 1976. The plants developed are medium tall, open and of semi-spreading type.

Water requirement (WR) = ET or CU + application losses + special needs. In hot climate evaporation loss is also being added. So, it is an overall combination of consumptive use, water required for special operations and other economically unavoidable losses of water.

There are three biodiversity hotspots present in India and total of 35 in the world. These are the Western Ghats, the Himalayas and the Indo-Burma region . Each one of them comprises at least 1500 species of vascular plants and it should have lost greater than or equal to 70% of its original habitat.

Intercropping is the most sustainable practice and is considered to be an environmentally sound and economically advantageous cropping system. Maize is mostly intercropped with legumes as it provides shade to legume species as they are smaller in size in comparison to maize plants. Thus intercropping of maize and soybean are complementary relations, as both complement each other.

Rice, Oryza sativa is believed to be originated from India. Historians believe that the indica variety of rice was first domesticated in the area covering the eastern Himalayas (north-eastern India), stretching through Burma (now called Myanmar), Thailand, Vietnam and southern China.

Dormancy is a strategical condition of higher plants to survive adverse conditions by pausing growth and development, and it can occur in any organ like seeds or buds, etc. It can be controlled both by genetic and environmental factors. While Potassium nitrate is the strongest chemical used for breaking dormancy.

A mint is a name of an industry that manufactures coins that can be used as currency. The first mint was established in Lydia in the 7 th century BC for coining gold, silver and electrum.

Here option D, Maize ⇔ Swarna is not correctly matched as Swarna is not any variety of maize crop. While the similar named variety of maize is Suvarna Nmh 589 seeds. All others correctly match the crop with its variety.

Khaira disease is associated with paddy. It is a micro nutritional deficiency disease characterized by the presence of dusty brown patches on leaves which ultimately undergo necrosis. It affects the leaf of the plant because of which the rate of photosynthesis is decreased ultimately affecting the production. The essential nutrient responsible for khaira disease in rice is Zinc.

PSM i.e. Phosphate solubilizing microbes are a group of beneficial microbes present in organic matter of soil that makes insoluble phosphate available to plants by mineralization process, they make it soluble which is then easily absorbed and assimilated by plants. Pseudomonas aeruginosa was reported first time as a promising phosphate solubilizer and biofertilizer.

Parshall flume is an open channel flow metering device that was developed to measure the flow of surface waters and irrigation flows. It is a fixed hydraulic structure. It is used to measure volumetric flow rate in industrial discharges, municipal sewer lines, and influent/effluent flows in treatment plants also.

The minimum percentage of clay in clayey soil is 40% and the maximum is 100%. The easiest way to recognize the clay soil is to check if the water sits around the soil after a rain, or if the soil is sticky, then it is considered clay soil.

The farmer first is a concept developed by ICAR. It stands for farmer's Farm, Innovations, Resources, Science and Technology (FIRST) . ICAR has proposed this concept to keep the farmer in a central role for all research programs for identification, prioritization, and conduct of experiments and its management in farmer's conditions.

Varalaxmi is the world’s first interspecific, the tetraploid cotton hybrid was developed by Cotton Research Station, Dharwad, University of Agricultural Science, Bangalore in the year 1972. It shows 50% higher productivity than other varieties.