Growing firepods in the Coastal Plains of North Carolina...
Mongrel Natural Hybrid Series 1
As discussed elsewhere (Notes: Cross-pollination), although pepper plants are generally classified as self-pollinated, they are subject to cross-pollination via transfer of pollen by insects. If you are growing two (or more) varieties that are capable of cross-pollination outdoors, some of the peppers on each plant are likely to be the
result of cross-breeding. While the pods themselves will be true to the mother (and thus visually indistinguishable from purebred pods), the seeds will not be true and will produce a natural hybrid of the two parent varieties. Since a single grain of pollen produces a single seed upon contact with the stigma of a flower, it is possible for the seeds in a given pepper to
have different fathers. Accordingly, saving pure seed requires isolation of the individual plants used for seed to prevent
inter-variety pollination (Notes: Plant breeding).
Given that Capsicum annuums will cross with any other annuums, and that most varieties grown by home gardeners are of the annuum species, this is a consideration for any pepper gardener that saves seeds.
Beginnings of Mongrel
When I decided to experiment with saving seed in 2000 I opted to take advantage of the genetic diversity provided by cross-pollination, rather than going to the trouble of avoiding it, letting nature run amok and then using 'unnatural selection' to emphasize the traits that I want in the resulting strains.
Since the Cayenne pod type is an indispensible, must-have pepper in my garden, I decided to use a very nice Cayenne variety called Charleston Hot as the first generation mother variety. Accordingly, I saved the first four ripe peppers from each Charleston Hot plant (see Notes: Saving seed).
The desired traits for the Mongrel series are 1) large number of peppers and 2) early yield, with 1) taking precedence over 2).
Forced trait selection
Really simple... save the best fruit from each plant within a group, and then use only the seeds from the plants that most strongly exhibit the traits that you want to emphasize. When done in the absence of further cross-pollination, this forced 'survival of the fittest' (known as the 'Mass Selection method' of plant breeding) would be
expected to provide a gradual, but eventually close, convergence with the 'ideal' plant.
In my case, the strong possibility of random male parentage in each generation would, at best, make for a rockier road to the ideal, and at worst may prevent convergence altogether; it will also most assuredly make the process more interesting.
But... see Hybridization: The Ugly Truth below.
Mongrel Series Plant Scoring
In order to compare a set of plants to determine which ones are 'best', a set of criteria defined in mathematical terms is required. As stated above, the desired traits are large numbers of peppers and early yield, with the emphasis on harvest size. To quantify these traits, a set of calculated indices is used.
The Harvest Size Index, In, which ranges from 0 to 100, compares the number of peppers a given plant produces, ni, to the maximum number of peppers produced by any member of the series, nmax, and is calculated such that the best plant will always score as In = 100. Thus:
The Harvest Speed Index, Id, which also ranges from 0 to 100, compares the number of days to 50% harvest for a given plant, di, to the maximum and minimum number of days to 50% harvest for that series (dmax and dmin respectively). The Harvest Speed Index is calculated so that the
fastest plant will always score Id = 100 and the slowest plant will always score Id = 0. Thus:
These two indices are then used to calculate an overall index IO, which provides a simple ranking of the plants based on both criteria. IO gives harvest size three times the weight as it does harvest speed, and is calculated such that 0 <= IO <= 100, thus:
First Mongrel generation: Start
Plant C5 had the largest yield of the five Charleston Hot plants, so I used it as the mother. I removed the seeds from each of the four peppers saved from C5, keeping them
separate, and labeling them 1A (first pepper) through 1D (last pepper).
In 2001, I started one cup (three seeds) from each of 1A - 1D, labeling these cups C1 through C4 respectively. This limited arrangement produces exactly four children, all of potentially different male parentage.
Germination rates and times were comparable for the four types (67-100% observed germination and 7-11 d to stand), except for one late germination time for 1B (22d to stand). Time to the development of the first true leaves was comparable for the 1A, 1C, and 1D cups (11-13 days), with the 1B cup lagging behind (19 d).
While the 1B cup produced two seedlings, they were both weak and sickly, and neither survived (very unusual in my experience). The other plants, at 73 days, showed comparable development, except that the 1C plant
had not branched yet, where the main stems of the 1A and 1D plants had both branched. All three plants had developed buds at this point, but none had flowered yet; budding was comparable between 1A and 1D, with 1C showing significantly fewer buds. 1D set fruit first (84 days), followed by 1A (88 days) then 1C (95 days).
The first ripe pods were harvested from 1A and 1D at the same time (134 days); first harvest from 1C occurred a week later (141 days). Days to 50% harvest were 154 (1A), 165 (1C), and 154 days (1D). Total harvest numbers were 68, 126, and 89 peppers respectively. As can be seen in the plot below, which shows % of total harvest vs. time, 1A and 1D produced ripe peppers at equivalent
rates, percentagewise, until the first week of August, when 1D's production slowed dramatically. 1A completed its production the fastest, reaching 100% at the end of September, where, after its initial burst of production, 1D had the longest production period, finishing on 19 November. 1C had an intermediate production curve; it started out producing at a slower rate, percentagewise, that 1A and 1D, and after 1D
slowed down, 1C's production rate was between that of the other two plants. 1C completed production on 25 Oct.
Hybridization: The Ugly Truth
Since 2001, I have read up a bit more on plant genetics and hybridization, and (as always) things are not quite as simple as they seem. A bit simplistically: Cross two different stable, true-bred, genetically pure varieties of pepper plants, and the resultant seeds, known as the F1 generation, will produce a homogeneous set of sibling plants
that are essentially alike. So far, so good. However, even if the F1 plants are self-pollinated, "[s]eed taken from... mature [F1 hybrid] pods will not produce peppers true to type, and numerous plants unlike the parents will result." (Ref 11 p. 173) This wild generation, known as the
F2 generation, "has the most visible genetic variation of any generation...and contains all combinations of parental traits." (Ref 13)
From this point, under my outdoor growing conditions, things get even more mixed: "If F2's are allowed to cross-pollinate each other, the parent genomes will become increasingly mixed. An intermediate type which is a blend of the parent types will come to prevail [after several generations] under
[repeated] cross-pollination. Although the progeny will become more and more homogenous in appearance... a great deal of genetic variability... will be maintained in equilibrium. Occasionally, unusual types will crop up out of this
genetic variability." (Ibid.)
This, of course, assumes that only the descendants of the original cross are cross-breeding. Given the variety of plants that I grow, and the proximity in which they are grown, promiscuity is the rule rather than the exception, and it is a given that the Mongrel plants will interbreed with other varieties from outside the family, introducing even more genetic
variability with each subsequent generation.
The result: a weltering, chaotic mess, in which genetic material is casually and randomly swapped without regard for law or morality; a mess in which no convergence is even remotely conceivable; a mess from which no stable line could possibly extricate itself.
The options: 1) Quit. Naaah. 2) Follow a more rigorous breeding regimen, utilizing techniques to control cross-breeding, to eventually develop stable plant lines. Maybe sometime in the future. 3) Continue with the current regimen, recognizing that it will lead to nothing but ever-changing generations of varied, unlike pepper plants, each generation stranger, more chaotic than the last.
Yeah... I like surprises.
Last updated 31 January 2015.
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