Seed dimensions in the subspecies and cultivar-groups of Cucurbita pepo

Seed samples of 174 accessions of pumpkins, squash, and gourds of Cucurbita pepo were measured for length, width, and thickness. Mean seed length ranged from 8.8 to 23.3 mm, mean seed width from 5.0 to 12.5 mm and mean seed thickness from 1.2 to 3.8 mm. The seeds of the edible-fruited cultivar-groups of C. pepo subsp. pepo (Pumpkin, Vegetable Marrow, Cocozelle, Zucchini) were longer, wider, and thicker than those of their counterparts of C. pepo subsp. texana (Acorn, Crookneck, Scallop, Straightneck). The small-fruited, inedible gourds had the smallest seeds. Of the edible-fruited C. pepo subsp. pepo, the Pumpkin Group (round fruits) possessed the longest and flattest seeds whilst the Zucchini Group (long, uniformly cylindrical fruits) possessed the shortest and thickest seeds. The samples tested also differed greatly in mean values for relative dimensions. Length-to-width ratio ranged from 1.5 to 2.5, length-to-thickness ratio from 3.7 to 8.2, and width-to-thickness ratio from 2.0 to 4.9. The Pumpkin Group, followed by the Cocozelle Group (long, bulbous cylindrical fruits) and the Vegetable Marrow Group (short, tapered cylindrical fruits), had seeds of the highest length-to-width ratio. The seeds of the four edible-fruited groups of C. pepo subsp. pepo differed significantly from one another in their length-to-thickness and width-to-thickness ratios. The seeds of the Pumpkin Group and the wild Mexican gourd (C. pepo subsp. fraterna) differed greatly in their dimensions but were most similar to one another in their relative dimensions. In C. pepo, seed size is positively associated with fruit size and seed shape is inversely associated with fruit shape.