From jackrowe@compuserve.com Sun Feb 8 23:28:45 1998 Date: Sun, 8 Feb 1998 14:41:01 -0500 From: Jack Rowe To: UNC Perm List , Envirolink Perm List Subject: Saving Corn Seed [The following text is in the "ISO-8859-1" character set] [Your display is set for the "US-ASCII" character set] [Some characters may be displayed incorrectly] For UteB and others wanting to save seed from vegetable plants, here are a couple notes relating to population size vis-a-vis saving seed, esp. from corn [taken from Seed Saving Handbook, Rowe, Seeds of Texas Seed Exchange]: "Among plants which reproduce sexually, collecting seeds from too-few parents can result in dangerous narrowing of a variety's genetic base. The resultant weakening of the variety is called "inbreeding depression". Since each individual plant typically does not contain all the available genes belonging to the variety, some minimum number of plants is needed in order to maintain the diversity and vigor of the variety. The degree of danger from inbreeding depression, and the number of parent plants needed to avoid it, depends on several factors. One factor is the variability of the variety^ืthe greater the variation between individual plants in a population, the more plants will be needed to preserve their collective genetic base. Another factor is the method by which pollination is accomplished between parent plants within the variety. As few as one or several plants may suffice for self-pollinated plants such as tomatoes or beans, since these plants do not normally rely on cross-pollination between different plants to maintain a healthy degree of genetic variability. Partially-self-pollinated plants, such as peppers, lettuces, etc., do not rely heavily on cross-pollination and can maintain their genetic health with a relatively-small number of parent plants, say 10 or more. A plant notable for needing a particularly-large parent population for long-term breeding health is corn, which needs at least 200 parent plants to produce healthy seed batches." [And, specific to corn]: "Another important consideration in growing corn for seed is the size of the planting. Corn represents an extreme example of the necessity for growing a large enough number of plants to avoid inbreeding depression. Corn requires a parent population of 200 or more plants for continuing vitality of a plant population, with seed collected from as many of those plants as possible. A healthy planting of seed-corn should start with 300 or so seeds, and care should be taken not to let a planting fall to too few plants for continued genetic vitality. One idea for broadening an existing seed batch's genetic base is to mix it with the same variety seed grown by different growers." Be sure to follow these guidelines when growing corn! Good Luck, Jack