Carrot seedling vigor

It seems to me that there is still a place for the backyard plant breeder.

For instance, there is much room for improvement in seedling vigor of carrots, Daucus carota.

The primary impediment to seedling vigor is that the seeds of most common carrot varieties is tiny with most of them running 1.3 milligrams per seed.

Believe it or not, there are databases that list the seed weights of carrot cultivars (cultivated varieties). 109 of the 2775 varieties listed have seed weights above 3.0 milligrams per seed. 61 of the 109 hail from the country of India. Most of those are named "Gazar" or "Gajar". I assume that is "Carrot" in many of the major languages used on the Indian subcontinent.

It is also interesting that carrot seeds are sometimes used in Ayurvedic Medicine. Since the ratio of seed-coat to germ is higher when seeds are smaller, it seems reasonable that crops that are harvested for their "germ" will be larger than seeds not used for those purposes.

High Carotene Mass Carrots

The University of Wisconsin stumbled into a breeding line that had approximately three times as much carotene (beta-carotene is a precursor to Vitamin A) as most carrot varieties.

By selecting carrots from subsequent generations that had both high carotene and acceptable culinary characteristics, the scientists were able to raise the carotene content about 10% every generation. By 1989, they had a population of inbreds (used to produce hybrids) with carotene levels of more than six-times the average for carrot varieties.

The point being that researchers were able to keep moving the needle generation-by-generation.

A proposal

Some young fellow with ten years and a hundred square-feet of garden space plants some of these Indian heavy-weight seeds and saves the carrots. The next year he/she plants out the carrots along with some hybrids (the carrot root itself, not seeds) with good culinary characteristics and disease resistance. The goal is to have them cross-pollinate.

The seeds are collected and they are first sorted for weight using a laminar-flow, winnowing box. For the sake of illustration, suppose he collects 10,000 seeds which is only an ounce at 3mg per seed. If he saves the heaviest 10% and plants them in trays and then collects the first 10% to germinate to plant out, then he would have 100 plants to produce the next generation of seeds (the next 10,000 seeds).

If he started with more than he could exert even heavier selection pressure.

Since carrots are biennials, he could have two seed-lines he was developing in parallel. Maybe one is for seed-weight and the other is for speed of germination. Runty roots would be culled from the program. The bottom of the carrot can be sampled for eating quality and the top-half is plenty to plant in the spring for seed production.