Originally published on liseed.org June 2007
The surprise melon of 2005 for us was a very nice golden rind variety from Asia sold as Yellow Jubilee (available from Dimension Trade Company, Scappoose, OR). It was the earliest to produce fruit and we found smaller, later fruits that we didn't harvest stayed in good shape in the field for considerable time. I suspect that the genetics are similar to the 1991 AAS Winner, "Golden Crown" developed by the Taiwan based Known-You Seed Co. which produces a similar sized early, very sweet melon. Most yellow skin watermelons start out green and change to their golden color as they ripen. This "ripeness indicator" is a trait that is often promoted by seed vendors selling "Golden Crown".
Yellow Jubilee (appears to be a variety produced by Long Hoang Gia Seed) is curious as it starts out completely yellow unless the plants are stressed. No ripeness indicator? I prefer to thump the melon listening for hollowness and look for the drying of the tendril next to the fruit stem in order to determine ripeness.
In both 2006 and 2007 we grew the seed of the second and third generations of seeds saved from Yellow Jubilee. There is quite a bit of variation in seed characteristics (size, color and pattern) indicating that indeed, as presumed, Yellow Jubilee was a F1 hybrid. Below you can see variations in fruit and plant also very apparent in recent generations. The fruit, instead of starting out completely yellow, can be mottled green and yellow to entirely green turning yellow at maturity or remaining green. Some interesting genetics. Many of the plants show the characteristic chlorotic condition of yellow skinned watermelons. Stems and leaves have a definite yellow look as chlorophyll fails to be produced in the cells adjacent to veins. This is not a nutrient deficiency but instead is genetically linked to the yellow skin characteristic.
The green skin F3 generation melons show normal leaf characteristics.
The yellow skin watermelons get their characteristic from a single recessive "go" gene named by Cornell breeder, Dick Robinson, for Royal Golden, an heirloom melon he studied the genetics of 25 years ago. Just why some yellow skinned watermelons start out yellow while others turn from pure green to yellow is a matter of how the "go" gene is expressed and the intermediate yellow and green immature fruit of the F3 generation of Yellow Jubilee may provide a clue in how the gene is expressed. It doesn't help that water stress and other environmental factors can cause some variability in gene expression. This year we're backcrossing some of the yellow skin F2's with the original F1 to increase the expression of immature yellow skin fruit.
Royal Golden, source of the "go" gene, is a large melon looking a lot like a pumpkin when it ripens from green to orange is still available through some small seed companies that preserve the older varieties. I don't know if it is the same cultivar as Pumpkin Rind (which I haven't grown). I suspect that it is very similar. Pumpkin Rind is mentioned as the yellow skinned parent of another melon still seen in commerce, Golden Midget which was developed in the late 1950's at the University of New Hampshire by Elwyn Meader and Albert Yeager. Golden Midget gets it's better qualities from New Hampshire Midget, a small, early sweet melon which is green skinned.