Plant Pathology MCQ Question and Answer | Agriculture MCQ Question

Olsen's method, which is used for the phosphorus detection method used in the soil is all expected sodic soils.
The Olsen method is a chemical extractant (bicarbonate) that provides a reasonable estimate of the amount of plant-available P by measuring phosphate from the soil solution and exchange surfaces.
This procedure is suitable for all expected sodic soils, calcareous, alkaline, neutral and slightly acidic soils containing CaPO₄, since the calcium concentration in the solution is suppressed by the precipitation of CaCO₃, increasing PO₄ concentration in the solution.

0.5 × 1.0 - 1.5μ is the average size of a bacteria.
Bacteria are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms.
Bacteria display a wide diversity of shapes and sizes. Bacterial cells are about one-tenth the size of eukaryotic cells and are typically 0.5 - 5.0 micrometers in length.

The rice blast pathogen's perfect stage is Magnaporthe grisea.
The fungus that causes rice blasts is called Magnaporthe oryzae (formerly Magnaporthe grisea).
It is an ascomycete because it produces sexual spores (ascospores) in structures called asci, and is classified in the newly erected family Magnaporthaceae.

The period between infection and sporulation of a pathogen is known as Latent period.
The period from the time of infection to the time of becoming infectious is called the pre-infectious period or the latent period.
The latent period is the time taken by a phage particle to reproduce inside an infected host cell. The infection of disease begins when a pathogenic (disease-causing) infectious agent, or a pathogen, is successfully transmitted from one host to another.

The sequence of the Krebs cycle is Isocitric acid ⟶ Oxalosuccinic acid ⟶ α-Ketoglutaric acid.
The citric acid cycle (CAC) also known as the Krebs cycle is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats and proteins.
The cycle harnesses the available chemical energy of acetyl coenzyme A (acetyl CoA) into the reducing power of nicotinamide adenine dinucleotide (NADH).

Anthesis means the opening of a floral bud.
Anthesis is the period during which a flower is fully open and functional. It may also refer to the onset of that period.
Anthesis of flowers is sequential within an inflorescence, so when the style and perianth are different colours, the result is a striking colour change that gradually sweeps along the inflorescence.
Flowers with diurnal anthesis generally are brightly colored to attract diurnal insects, such as butterflies.

Embryoids formed in tissue culture from pollen grains are due to Cellular totipotency.
Cellular totipotency is the inherent potentiality of a plant cell to give rise to a whole plant, a capacity that is retained even after a cell has undergone final differentiation in the plant body.
A cell can differentiate into other cell types. The more cell types a cell can differentiate into, the greater its potency.

Hill reaction occurs in Presence of ferricyanide.
The Hill reaction is the light-driven transfer of electrons from water to Hill reagents in a direction against the chemical potential gradient as part of photosynthesis.
Robin Hill discovered the reaction in 1937. He demonstrated that the process by which plants produce oxygen is separate from the process that converts carbon dioxide to sugars.
The association of phosphorylation and the reduction of an electron acceptor such as ferricyanide increase similarly with the addition of phosphate, magnesium (Mg) and ADP.

Common scabs of potato can be controlled by reducing pH below 5.2 is caused by the pathogen Streptomyces scabies.
Common scab of potato is caused by Streptomyces scabies and occurs throughout the world. It is most prevalent and important in neutral or slightly alkaline soils, especially during relatively dry years. The same pathogen also affects beets, radishes and other root crops.
Scab problems tend to disappear when soil pH is less than 5.2. Therefore, acidify garden soils (i.e., make sure the soil pH is less than 7) to control the infection.

The common weedicides act by Interfering with photosynthesis.
weedicides inhibit photosynthesis by binding to D1 proteins of the photosystem II complex in chloroplast thylakoid membranes.
Chemical substance binding at this protein blocks electron transport and stops CO₂ fixation and production of energy needed for plant growth.