Diallel Denoting hereditary lines which cross. A diallel cross involves all possible matings of several known males and females.

Dimorphism A difference in size, form, or colour, between individuals of the same species, characterising two distinct types.

Drip irrigation A planned irrigation system in which water is applied directly to the Root Zone of plants by means of applicators (orifices, emitters, porous tubing, perforated pipe, etc.) operated under low pressure. The applicators may be placed on or below the surface of the ground. Also see Irrigation Systems.

Embryo Derives from embryon, from bryein;
1. The young plant developed from the fertilized egg cell.
2. A rudimentary plant still enclosed in the seed, the young sporophyte resulting from the union of male and female sex cells. See illustration of cross section of fruits or vascular connection between shoot and root.

(I will include pictures if any after the definitons)