Toxicity

A measure of how poisonous and harmful a substance is.

  Trailed Gang Mower

A cylinder mower which is towed behind a power unit such as a tractor. The number of units will typically be 3 or 5 but can be more. A range of manufacturers make trailed gang mowers. A typical 3 gang mower will have a cutting width of 2.13m and have a cutting performance of 1.5 hectares per hour at a speed of 10 kilometres per hour; whilst a 5-gang mower will have a cutting width of 3.5m and have a cutting performance of 2.5 hectares. Trailed gang mowers are typically powered by the motion of their side wheels, which are usually either steel wheels or having pneumatic tyres.

  Transpiration

Water which is lost by a plant as water vapour. Water moves into the plant via the root hairs, which are mostly located towards the apical (or tip) region. Water moves through the outer cells that surround the xylem within the root and into the xylem ready for further movement within the plant. The xylem consists of two key features: tracheids, which have perforated sides, and vessels, which have perforated sides as well as perforated ends. This network of interconnected cells provides the means by which water is moved up through a plant. Water is lost, as water vapour, through the stoma

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  Tricarboxylic Acid Cycle

This is another name for the Krebs Cycle.

  Tropisms

The response of plants to stimuli, resulting in growth taking place being towards or away from the stimuli. The main tropisms are Phototropism; Gravitropism; and Thigmotropism.

  Uneven Cut

An uneven cut which will typically produce a ridged type of appearance, with one side of the mower being set to a different height than the other side.

  Uniformity

Plant Breeders have rights of protection over plant varieties with uniformity being assessed for all characteristics used to establish Distinctness and 'A variety can be considered sufficiently uniform after two years of tests'.

  Vacuole

A container, called a sac, within a plant cell which contains fluids which can expand the sac up to about 90% of the cell volume, when well supplied with water, producing more turgid plant cells. When water is in limited supply, especially during drought conditions, then vacuoles will contract creating flaccid plant cells.

  Variance

The average of the squared deviation (or difference) of a variable from the mean; this identifies the extent of the dispersion or spread of the values. The variance is helpful for making inferences from data, although standard deviation (which is the square root of the variance) is often the preferred method of determining variability in data. Two methods of variance are used, either population variance (where all data of a group are included – this would only be applicable for small surveys) or sample variance (where a sample of a group is being used and is probably the most common approach).

  Variety

A plant taxonomic category between a species and a form. A variety is a naturally occurring organism without human intervention, unlike a cultivar, and it exhibits a minor difference within a species (or sub-species). This is a plant with a minor variation from the main species description, for example, a plant with variegated leaves.