Goldini Zucchini Summer Squash—Description and Breeding

(by Carol Deppe)


Description: Goldini Zucchini summer squash (Cucurbita pepo)

Triple-purpose zucchini. Bred for organics. Bred for dual use as a cooked summer squash, and for drying for a long-storing staple. Has a delicious flavor raw and a crunchy texture. Is actually so good raw that I would happily grow it just for that use. (Try it just sliced with a feta cheese dressing.) Bred for its spectacular flavor cooked as well as dried, its characteristic of being prime at unusually large sizes, and extremely high yield, growth rate, and plant vigor. Other zucchinis are prime only up to a few ounces; Goldini is prime with no loss of flavor or texture at weights up to about two pounds. It is also bred specifically for use for drying as described in The Resilient Gardener. The young squash can be dried at sizes up to about 4 pounds, and the flavor of the dried slices is powerful and powerfully delicious; in slices or powdered, the dry squash makes a marvelous base for winter soups and stews. Sliced about ¼” thick and dried, it makes great chips. (Any green stage squash can be dried; most don’t have much flavor when dried, or can be dried only when quite small. Goldini Zucchinis are great for drying after they have escaped prime stage. With Goldini Zucchini, never again will you have to sneak boxes of overgrown squash at midnight onto the porches of your long-suffering neighbors. You can instead turn all the escapees into dried squash, and get fresh summer squash and a long-storing staple from one variety.) The sliced cooked squash is so delicious, I think they would make a great commercial frozen vegetable as well as a great baby-food turned into a puree with just a little salt. (They are actually a bit sweet in the summer squash stage all by themselves.) May be the fastest germinating and growing squash on the planet. Plants are all vigorous productive bushes with early fruit development. Leaves may be solid green, speckled, silver, roundish, dissected, or sharp-pointed. Some young plants have goldish leaves; others don’t. Some pedicels (fruit stems) are yellow; most are green. Let genetic heterogeneity live! Goldini Zucchini has been selected for uniformity only for the traits that matter; genetic heterogeneity is part of the basis for its explosive germination and growth rate, plant vigor, productivity, and resilience. A small percent of green-fruited or bi-color fruited plants may segregate. Bred by Carol Deppe/Fertile Valley Seeds.


Breeding History Summary:


Gold Rush hybrid zucchini (Seminis). (Gold exterior, white interior. Heterozygous for B.)

Costata Romanesco summer squash, an Italian heirloom. (The line Johnny’s sells) Light green exterior, white interior. Fruits have distinctive ridges.

 Cytoplasm: Costata Romanesco

 Source and characteristics of B gene: Gold Rush hybrid is heterozygous for B, the Bicolor gene. B was transferred from a pear-shaped gourd to culinary C. pepo via recurrent backcrossing by Oved Shifriss (Rutgers). Shifriss released material to seed companies, who used it to breed precocious yellow zucchinis, patty pan, and other varieties. The gene is dominant and apparent at the bud stage, greatly facilitating working with it. B can express as yellow fruit or bicolored fruit depending upon exact allele, heterozygosity versus homozygosity, and genetic background.


Breeding Mechanics:

I crossed the best of several gold-fruited F2 plants from Gold Rush hybrid to the best of several Costata Romanesco plants with Costata Romanesco as female parent. I grew out a row of the offspring and selfed the best gold-fruited plant. From there I mass selected for fast germination, vigorous growth, solid gold fruit color, gold interior color, earliness, fruit size, and productivity.


Additional details and comments:

I had worked on two other breeding projects involving the B gene before the Goldini, so knew what to expect when working with it. All the characteristics of Goldini were actually deliberately designed and bred for, including the flavor fresh and dried, the optimizing for new commercial uses as well as use as an ordinary zucchini, the ability of the fruit to be prime at unusually large sizes, and the outrageously fast germination and growth rate. (Of course, this was after I did an entirely different project with B with different goals, decided the project had different possibilities than what I had initially planned, but only if the fruits were much bigger and a different shape, then starting over again with different parents and different goals.) Here’s how I bred for these various characteristics (using the relationships between genes, flavors, phenotypes, and use potential I had figured out in the prior projects).


Spectacular special flavor both fresh and dried.

This comes predominantly from B, that is, the Bicolor gene, the basis for all the precocious yellow zucchini hybrids. These have a powerful flavor I really like which is great both fresh and dried. The hybrids are generally heterozygous for B, and have yellow skins but white interiors. I discovered in prior breeding projects involving B that homozygotes are way more delicious than heterozygotes, both fresh and dried. (I’ve read that homozygotes give you skinny malformed fruits, but not for me they don’t.) And yellow interiors are more delicious too. And the yellow interior means higher carotene content too. Using the dried squash allows getting lots more squash into a soup or stew than using fresh. And for use as a staple or baby food I want the high carotene content.


I’ve read that the yellow interior of B_ fruits at the summer squash stage is associated with a single additional dominant gene, L-2. This is at best simplistic, I think, or applies to just a few specific crosses rather than generally. The Gold-Rush F2 parent did not have yellow interior color. Nor did the Costata parent. Nor did the fruits on the plants that resulted by crossing them. The interior yellow color only showed up in later generations. There is clearly at least one recessive involved. In another project, I got yellow interior color whenever the plants were homozygous for B. In the current project, the trait acts like a quantitative trait, with every shade of interior color from white to dark yellow. I’ve been treating yellow interior color in the presence of B in this project as a quantitative trait, which works well whether it is or not. There is such a strong correlation between interior and exterior yellow color that all fruits with full rich yellow color inside and out have virtually indistinguishable flavor both as fresh cooked squash and dried. I also selected for thick flesh in the zucchini stage, as the yellow interior color is in the fleshy interior only, not the part that will become the seed cavity.


Breeding for fast germination and very rapid grow rate.

I think one of the most critical characteristics for organic-adaptation is simply extremely vigorous rapid growth. With fast enough growth, the plants can simply outgrow many pests and diseases. And they are also more resilient with respect to suboptimal weeding. And they quickly establish deep roots that tap into moister soil, so are more resilient to drought or other water issues. So fast germination and rapid growth is a great help to both organic adaptation and general resilience. As part of this project I decided to deliberately try to breed the fastest germinating and growing squash on the planet. The objective was partly because of my observations and theorizing about the role of fast germination and fast growth rate in a variety’s being adapted for organics. But also, wouldn’t it be fun if I could breed an op OSSI-Pledged variety that was demonstrably faster germinating and growing under field conditions than anything else, including the hybrids? (Have I tested Goldini against the parents? No. A single year’s test might give results more reflecting seed quality that year or weather-adaptation of specific varieties than being general. It will take years of tests, and in various regions and weathers. And with various lots of seed of the hybrid. All in good time.)


Of all squash varieties I have grown, two consistently, year in and year out, germinate faster as well as grow faster than any others. One is the hybrid Gold Rush. The other is the heirloom Costata Romanesco. In side by side comparisons these germinate equally fast, and outgrow simply everything else. (In Seminis info on Gold Rush, they say it germinates and grows faster than all other hybrids, something I had independently concluded before I ever read it.) So to breed a squash that germinates and grows faster than any other on the planet, I did the obvious thing. I started by crossing those two. (Which I had other reasons for crossing too.) Then at all stages I selected heavily for fast germination and vigorous growth by always overseeding by several fold and culling to the biggest plants when they got about 6 or 8 inches high.


My observation on spontaneous chlorophylless mutants of big seeded plants like peas, corn, or squash, is that these plants grow as fast as normal sibs up until they are about 2 inches high; then they stop cold and die. What is interesting is that they grow as well as normal plants until that stage. This implies that the performance of seedlings is based more upon the genes of the mother than the genes in the seedlings until much later than one would suspect. The plants have to get to above 2 inches before the products of maternal metabolism are diluted enough so that the growth depends upon the genes in the seedling. So to select for fast growth, I do overplant and cull when the plants are well above that stage.  I sow seeds at 6 inches apart in rows, then let the plants get to 8 inches high, then thin to the best plants with 3 to 5 foot spacing. I plant several fold more seed than plants I am going to keep, with the initial cut being based upon size of young plants. (Even after a variety is finished, I still oversow—I plant 3 seeds per hill and thin to the best one.)


Part of my strategy for breeding for fast growth and vigor in squash is to come as close as possible to avoiding all inbreeding as well as deliberately maintain as much as possible of the genetic heterogeneity I create by selected only for characteristics that matter. In developing Goldini, there is one self-pollination of one plant after the outcross, but all subsequent breeding was by mass selection starting with a hundred or more plants per generation, with at least 35 contributing to the next year’s seed each generation. (Where I have had to inbreed, such as my winter squash breeding projects, I have developed multiple inbred lines, then recombined them to recover as much as possible of the lost genetic heterogeneity.)


Breeding a drying squash.

I did a good bit of original research on evaluating squash for drying and reported it in The Resilient Gardener. Basically, the American Indians mostly used squash fresh and dried summer-stage squash slices, the latter of which were the long storing staple. Dried sliced summer stage squash was the storage produce from squash, not fully mature squash. Indians mostly didn’t have enough indoor space or good storing conditions to store fully mature squash. So fully mature squash were eaten pretty soon after harvest rather than used as a staple. I figured out how to produce the dried sliced squash from Buffalo Bird Woman’s Garden, which is about the agriculture of the Hidatsu and Mandan Indians. Drying sliced summer squash was a major industry. There were special knives for making the slices, special drying sticks and drying racks, etc. I developed modern equivalents. The book said the different squash they used all tasted the same dried. I think they either had just one variable variety or never actually tested the different colors separately. I did evaluations of many squash varieties as dried squash and found, first, that most are tasteless, a few taste positively bad, and just a few taste great. But the great ones are really great. When dry the flavors are very different from those of the fresh squash, and quite distinctive. (Sort of like the difference in flavor between fresh prune plums and dried prunes. Two totally different flavors.) Dried sliced summer squash is so good that it’s actually as important as fresh summer squash to me. And, like Buffalo Bird woman, I built a special rack just for drying squash. I also developed other methods, though. Such as shooting the squash through a salad shooter onto dehydrator racks so as to get dried slivers of squash that reconstitute in a soup in just a couple of minutes. And using 1/8 inch slices instead of 3/8 inch slices to make squash chips that can be used with dips.


In evaluating squash for drying, flavor was the first criterion, since most squash varieties taste pretty much like nothing dried. But once I had a squash with great flavor, there were other issues. Namely, the squash must be immature. The skin has to be tender, and the seeds need to be undeveloped. Many summer squash are actually fully mature at sizes not much bigger than the size that’s prime for use as summer squash. These don’t work as drying squash. At least not if part of the point is to be able to dry fruits that have escaped prime fresh eating stage. And that was one of my objectives. In addition, it’s inefficient to use small squash for drying. I wanted to be able to use bigger squash, so evaluated fruits for flavor dried when they were bigger than the ordinary size for using as prime fresh squash. To have a squash be workable as a drying squash at sizes much bigger than prime, all it needs besides flavor, it turns out, is for the squash variety to be “intending” to produce really huge mature squash. Both Gold Rush hybrid and Costata Romanesco, for example, are capable of making fruits that are 2 ½ feet long and 8 inches wide. For these varieties, a 1 1/2 foot long squash is still a baby squash, has a tender skin and tiny immature seeds, and is still great for drying. So to get squash great for drying when big, besides great flavor dried, what I needed was a variety whose idea of a mature squash is really big.


Breeding for a variety that is prime at much larger than ordinary sizes:

It turns out, plants that are intending to produce very large mature fruits are not only best for drying, they are also prime to much larger than the expected sizes for fresh use. Having the prime flavor and quality extend to large sizes gives greater versatility for use as a fresh zucchini, but is potentially very important for commercial use as frozen sliced squash or purees for baby food.