Plant Pathology MCQ Question and Answer | Agriculture MCQ Question

Anton de Bary is regarded as the father of phytopathology.
Heinrich Anton de Bary was a German surgeon, botanist, microbiologist, and mycologist. He is considered a founding father of plant pathology (phytopathology) as well as the founder of modern mycology.
Plant pathology is the science that studies the causes of plant diseases, the mechanisms by which diseases develop in individual plants and plant populations, and the ways and means by which plant diseases can be managed or controlled.

Kisan khad (CAN) contains 25 - 28% N.
Calcium ammonium nitrate or CAN, also known as nitro-limestone or nitrochalk, is a widely used inorganic fertilizer. Locally it is also known as Kisan khad.
Fertilizer grade CAN contain roughly 8% calcium and 21 - 27% nitrogen. CAN is preferred for use on acid soils, as it acidifies soil less than many common nitrogen fertilizers.

Gemini viruses are a group of plant viruses known for their single-stranded DNA (ssDNA) genome.

They belong to the Geminiviridae family, which is named after their characteristic geminate (twin) particle morphology. These viruses are circular, single-stranded DNA viruses that primarily infect plants, causing severe diseases in economically important crops.

Structure and Genome: Gemini viruses have two joined icosahedral capsids, forming their unique twin structure. Their genome consists of either a monopartite or bipartite ssDNA, depending on the genus. The two major genera are:

Begomovirus – Bipartite genome (DNA-A and DNA-B components)
Mastrevirus and Curtovirus – Monopartite genome (single DNA component)

Replication: Unlike RNA viruses, Gemini viruses replicate using a rolling-circle replication mechanism within the nucleus of host plant cells. They rely on the host's DNA replication machinery to propagate.

Transmission: These viruses are primarily transmitted by whiteflies (Bemisia tabaci), which act as vectors and spread the virus from infected to healthy plants. Some members of this family can also be transmitted by leafhoppers.

Diseases and Economic Impact: Gemini viruses are responsible for devastating plant diseases, leading to significant yield losses in crops such as:

Tomato – Tomato Yellow Leaf Curl Virus (TYLCV)
Cotton – Cotton Leaf Curl Virus (CLCuV)
Cassava – Cassava Mosaic Virus (CMV)
Maize – Maize Streak Virus (MSV)

These viruses cause symptoms like leaf curling, yellowing, stunted growth, and reduced productivity, making them a major concern in agriculture.

Management and Control: Controlling Gemini viruses is challenging due to their efficient transmission by insect vectors. However, management strategies include:

Vector control – Using insecticides and biological control methods to reduce whitefly populations.
Resistant crop varieties – Developing and planting virus-resistant or tolerant crops.
Cultural practices – Crop rotation, removal of infected plants, and use of virus-free planting material.
Genetic engineering – Developing transgenic plants with virus resistance genes.

Due to their significant impact on agriculture, continuous research is being conducted to develop better management strategies and resistant crop varieties to mitigate the effects of Gemini virus infections.

In plants, the common symptom caused by the deficiency of K, P, Ca and Mg is the appearance of necrotic areas in the leaves.
Necrosis is the death of a circumscribed area of plant or animal tissue as a result of disease or injury. Necrosis is a form of premature tissue death, as opposed to the spontaneous natural death or wearing out of tissue, which is known as necrobiosis.
Deficiencies of the nutrients nitrogen, phosphorus, potassium, and magnesium result in chlorosis (yellowing) and eventual necrosis (death) of older mature leaves.

Bacteria and fungi are pathogens belonging to the biotic type.
Fungi are a biotic factor in the ecosystem. Biotic factors include people, animals, fungi, bacteria, etc.
Abiotic factors are non-living components of an ecosystem mainly including soil, water, temperature and weather.

If turgor pressure becomes equal to osmotic pressure no exchange of water takes place.
Turgor pressure is the hydrostatic pressure over ambient atmospheric pressure which can build up in living, walled cells. Turgor is generated through the osmotically driven inflow of water into cells across a selectively permeable membrane; this membrane is typically the plasma membrane.
Osmotic pressure is the minimum pressure that needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane.

Downy mildew includes in Oomycetes.
Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants.
Downy mildew, is a disease of plants, especially in cool humid regions, caused by several fungus-like organisms of the phylum Oomycota. White, gray, bluish, or violet downy patches of mildew form mostly on the undersides of leaves in damp weather.

The class of Ascomycetes that comprises naked asci is Saccharomycetes.
Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as sac fungi or ascomycetes.
Naked asci occur in simple ascomycetes, asci are produced on the organism's surface. Saccharomycetes is a subdivision of the division Ascomycota in the kingdom Fungi. It comprises most of the ascomycete yeasts.

The most important symptom of wilt of cotton (caused by Fusarium oxysporum vasinfectum) is Discolouration of tissues and the plugging of vessels by hyphae.
Fusarium wilt, caused by the fungus Fusarium oxysporum f. sp. vasinfectum, is a major disease of cotton capable of causing significant economic loss. The fungus persists in the soil as chlamydospores and association with the roots of susceptible, resistant and non-cotton hosts as well as in seed.
Symptoms include yellowing, stunting, and death of seedlings and yellowing and stunting of older plants.

Supply end in solute transport is Green leaves and storage organs.
In any solute transport system, the supply end is an area or site, where the transported substance like food or water is stored for further use. It is mostly any storage organ or green leaves.