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M1, M2, M3

First, second, and third generations following exposure to a mutagenic agent.

Macro climate

The climate over a large area such as a region or country.

Macronutrient

A nutrient element absorbed by the plant in large amounts, often more than 0.1 % of its dry weight. The following are considered macroelements: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.

Macrophytes

Large plants, as opposed to microphytes such as algae and fungi.

Magnesium deficiency

Leaves become wavy and droopy due to the expansion of the angle between the leaf blade and the leaf sheath. Inter-venial chlorosis characterized by orange-yellow colour occurs on lower leaves. The spikelet number and grain weight is reduced. Mg deficiency occurs in acid soils with low CEC in uplands and lowlands, degraded, coarse, and highly weathered soils. It also occurs in highly leached, old acid sulphate soils with low base content.

Maintainer line

A pollinator variety used to pollinate the male sterile line and produce progenies which still retain male sterility. If there is no maintainer line, the male sterile line cannot be maintained and multiplied generation after generation.

Maintenance application

Application of fertilizer materials in amounts and at intervals to ensure a certain minimum level of an available nutrient.

Major cereal

A type of grass which is cultivated for its grains. Cereals are used especially to make flour for breadmaking, for animal feed or for producing alcohol. The major cereals are wheat, rice, barley, maize and oats.

Major gene

A gene that determines major characteristics.

Major gene resistance

Resistance in which genes show clear-cut and discrete segregation in the f2 or later generations of crosses between resistant and susceptible parents. Effects are thus qualitative.

Major pests

Unwanted organisms, such as insects, pathogens, weeds, small animals, etc. That compete with people for food and shelter, threaten their health, comfort, and welfare and cause serious problems.

Male flower

A flower with functional stamens but no ovary.

Male parent

The plant which is the source of pollen used in hybridization.

Male sterile

A plant having no pollen grains or nonfunctional pollen grains and therefore is unable to fertilize the embryo.

Mangrove

Tropical or subtropical vegetation (mainly trees) typical of tidal swamps.

Mangrove rice cultivation

Use of the cleared mangrove forest land for rice production.

Mangrove swamps

Low-lying coastal swamps where mangrove trees grow.

Manure application

Application of material used as fertilizer (e.g., organic material and excreta).

Manures

Materials used as fertilizer (e.g., organic material and excreta).

Map

Diagrams showing physical features, roads, town, etc. The ordered arrangement of genes or molecular markers of an organism, indicating the position and distance between the markers and loci.

Marginal cost

The increase in variable cost which occurs in changing from one production alternative to another; it is often measured relative to adding a marginal unit of input.

Marginal net benefit

The increase in net benefit which can be obtained by changing from one production alternative to another; it is often measured relative to adding a marginal unit of input.

Marker gene

A gene with a clear-cut phenotype (and often a known location on a chromosome) that is used as a point of reference when mapping or selecting another gene at a nearby locus.

Mass rearing

Rearing large numbers of insects, which serve as test organisms in varietal resistance studies.

Mass screening

Screening a large number of varieties in preliminary studies. Varieties selected as resistant in the mass screening trial are retested to confirm their resistance.

Mass selection

A breeding method wherein a large number of plants having the desirable traits are harvested individually from a standing crop. The seeds from all selections are then bulked. From the bulk, a seed sample is taken and used to plant a population from which desirable plants are selected at maturity. The procedure is repeated for several cycles until the population becomes uniform and homogeneous. A variety developed by mass selection is fairly uniform and contains fewer genotypes than the original population.

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